ACS8520 Datasheet

ACS8520 SETS
Synchronous Equipment Timing Source for
Stratum 3/4E/4 and SMC Systems
ADVANCED COMMUNICATIONS
Description
FINAL
Features
The ACS8520 is a highly integrated, single-chip solution
for the Synchronous Equipment Timing Source (SETS)
function in a SONET or SDH Network Element. The device
generates SONET or SDH Equipment Clocks (SEC) and
Frame Synchronization clocks. The ACS8520 is fully
compliant with the required international specifications
and standards.
The device supports Free-run, Locked and Holdover
modes. It also supports all three types of reference clock
source: recovered line clock, PDH network, and node
synchronization. The ACS8520 generates independent
SEC and BITS/SSU clocks, an 8 kHz Frame
Synchronization clock and a 2 kHz Multi-Frame
Synchronization clock.
Two ACS8520 devices can be used together in a Master/
Slave configuration mode allowing system protection
against a single ACS8520 failure.
A microprocessor port is incorporated, providing access to
the configuration and status registers for device setup
and monitoring. The ACS8520 supports IEEE 1149.1[5]
JTAG boundary scan.
The user can choose between OCXO or TCXO to define the
Stratum and/or Holdover performance required.
Block Diagram
DATASHEET
‹ Suitable for Stratum 3, 4E, 4 and SONET Minimum
Clock (SMC) or SONET/SDH Equipment Clock (SEC)
applications
‹ Meets Telcordia 1244-CORE[19] Stratum 3 and
GR-253[17], and ITU-T G.813[11] Options Ι and ΙΙ
specifications
‹ Accepts 14 individual input reference clocks, all with
robust input clock source quality monitoring.
‹ Simultaneously generates nine output clocks, plus
two Sync pulse outputs
‹ Absolute Holdover accuracy better than 3 x 10-10
(manual), 7.5 x 10-14 (instantaneous); Holdover
stability defined by choice of external XO
‹ Programmable PLL bandwidth, for wander and jitter
tracking/attenuation, 0.1 Hz to 70 Hz in 10 steps
‹ Automatic hit-less source switchover on loss of input
‹ Microprocessor interface - Intel, Motorola, Serial,
Multiplexed, or boot from EPROM
‹ Output phase adjustment in 6 ps steps up to ±200 ns
‹ IEEE 1149.1 JTAG Boundary Scan
‹ Single 3.3 V operation. 5 V tolerant
‹ Available in LQFP 100 package
‹ Lead (Pb) - free version available (ACS8520T), RoHS
and WEEE compliant.
Figure 1 Block Diagram of the ACS8520 SETS
T4 DPLL/Freq. Synthesis
2 x AMI
10 x TTL
2 x PECL/LVDS
Programmable;
64/8 kHz (AMI)
2 kHz
4 kHz
N x 8 kHz
1.544/2.048 MHz
6.48 MHz
19.44 MHz
25.92 MHz
38.88 MHz
51.84 MHz
77.76 MHz
155.52 MHz
TCK
TDI
TMS
TRST
TDO
T4
Selector
Optional
Divider, 1/n
n = 1 to 214
PFD
Digital
Loop
Filter
T4 APLL
DTO
Frequency
Dividers
Input
Port
Monitors
and
Selection
Control
T0 DPLL/Freq. Synthesis
T0 APLL
(output)
14 x SEC
T0
Selector
IEEE
1149.1
JTAG
Chip
Clock
Generator
Optional
Divider, 1/n
n = 1 to 214
PFD
Priority Register Set
Table
Digital
Loop
Filter
Microprocessor
Port
OCXO or
TCXO
Frequency
Dividers
DTO
Output
Ports
TO1
to
TO7
Outputs
T01-TO7:
E1/DS1 (2.048/
1.544 MHz)
and frequency
multiples:
1.5 x, 2 x, 3 x
4 x, 6 x, 12 x
16 x and 24 x
E3/DS3
2 kHz
8 kHz
and OC-N* rates
TO8
&
TO9
T08: AMI
TO9: E1/DS1
TO10
&
TO11
TO10: 8 kHz
(FrSync)
TO11: 2 kHz
(MFrSync)
TO APLL
(feedback)
OC-N* rates =
OC-1 51.84 MHz
OC-3 155.52 MHz
and derivatives:
6.48 MHz
19.44 MHz
25.92 MHz
38.88 MHz
51.84 MHz
77.76 MHz
155.52 MHz
311.04 MHz
F8520P_001BLOCKDIA_03
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Table of Contents
ADVANCED COMMUNICATIONS
Table of Contents
FINAL
Section
ACS8520 SETS
DATASHEET
Page
Description ................................................................................................................................................................................................. 1
Block Diagram............................................................................................................................................................................................ 1
Features ..................................................................................................................................................................................................... 1
Table of Contents ...................................................................................................................................................................................... 2
Pin Diagram ............................................................................................................................................................................................... 4
Pin Description........................................................................................................................................................................................... 5
Introduction................................................................................................................................................................................................ 8
General Description................................................................................................................................................................................... 8
Overview .............................................................................................................................................................................................8
Input Reference Clock Ports .......................................................................................................................................................... 10
Locking Frequency Modes .................................................................................................................................................... 10
PECL/LVDS/AMI Input Port Selection .................................................................................................................................. 11
Clock Quality Monitoring................................................................................................................................................................. 12
Activity Monitoring ................................................................................................................................................................. 12
Frequency Monitoring ........................................................................................................................................................... 14
Selection of Input Reference Clock Source................................................................................................................................... 14
Forced Control Selection....................................................................................................................................................... 15
Automatic Control Selection ................................................................................................................................................. 15
Ultra Fast Switching .............................................................................................................................................................. 15
Fast External Switching Mode-SCRSW Pin .......................................................................................................................... 15
Output Clock Phase Continuity on Source Switchover ....................................................................................................... 16
Modes of Operation ........................................................................................................................................................................ 16
Free-run Mode ....................................................................................................................................................................... 16
Pre-locked Mode ................................................................................................................................................................... 16
Locked Mode ......................................................................................................................................................................... 16
Lost-phase Mode................................................................................................................................................................... 17
Holdover Mode ...................................................................................................................................................................... 17
Pre-locked2 Mode ................................................................................................................................................................. 19
DPLL Architecture and Configuration ............................................................................................................................................ 19
TO DPLL Main Features ........................................................................................................................................................ 20
T4 DPLL Main Features ........................................................................................................................................................ 20
TO DPLL Automatic Bandwidth Controls.............................................................................................................................. 20
Phase Detectors .................................................................................................................................................................... 21
Phase Lock/Loss Detection.................................................................................................................................................. 21
Damping Factor Programmability......................................................................................................................................... 21
Local Oscillator Clock ............................................................................................................................................................ 22
Output Wander ...................................................................................................................................................................... 23
Jitter and Wander Transfer ................................................................................................................................................... 25
Phase Build-out ..................................................................................................................................................................... 25
Input to Output Phase Adjustment....................................................................................................................................... 26
Input Wander and Jitter Tolerance....................................................................................................................................... 26
Using the DPLLs for Accurate Frequency and Phase Reporting ........................................................................................ 28
Configuration for Redundancy Protection ..................................................................................................................................... 29
Alignment of Priority Tables in Master and Slave ACS8520 .............................................................................................. 30
T4 Generation in Master and Slave ACS8520 .................................................................................................................... 30
Alignment of the Output Clock Phases in Master and Slave ACS8520............................................................................. 30
MFrSync and FrSync Alignment-SYNC2K............................................................................................................................. 31
Output Clock Ports .......................................................................................................................................................................... 32
PECL/LVDS/AMI Output Port Selection ............................................................................................................................... 32
Output Frequency Selection and Configuration .................................................................................................................. 32
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ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Section
Page
Microprocessor Interface ....................................................................................................................................................................... 43
Introduction to Microprocessor Modes ......................................................................................................................................... 43
Motorola Mode ...................................................................................................................................................................... 44
Intel Mode.............................................................................................................................................................................. 46
Multiplexed Mode.................................................................................................................................................................. 48
Serial Mode............................................................................................................................................................................ 50
EPROM Mode......................................................................................................................................................................... 52
Power-On Reset............................................................................................................................................................................... 52
Register Map........................................................................................................................................................................................... 53
Register Organization ..................................................................................................................................................................... 53
Multi-word Registers ............................................................................................................................................................. 53
Register Access ..................................................................................................................................................................... 53
Interrupt Enable and Clear ................................................................................................................................................... 53
Defaults.................................................................................................................................................................................. 53
Register Descriptions ............................................................................................................................................................................. 57
Electrical Specifications ....................................................................................................................................................................... 133
JTAG ............................................................................................................................................................................................... 133
Over-voltage Protection ................................................................................................................................................................ 133
ESD Protection .............................................................................................................................................................................. 133
Latchup Protection........................................................................................................................................................................ 133
Maximum Ratings ......................................................................................................................................................................... 134
Operating Conditions .................................................................................................................................................................... 134
DC Characteristics ........................................................................................................................................................................ 134
DC Characteristics: AMI Input/Output Port ....................................................................................................................... 138
Jitter Performance ........................................................................................................................................................................ 140
Input/Output Timing ..................................................................................................................................................................... 142
Package Information ............................................................................................................................................................................ 143
Thermal Conditions....................................................................................................................................................................... 144
Application Information ........................................................................................................................................................................ 145
References ............................................................................................................................................................................................ 146
Abbreviations ........................................................................................................................................................................................ 146
Trademark Acknowledgements ........................................................................................................................................................... 147
Revision Status/History ....................................................................................................................................................................... 148
Notes ..................................................................................................................................................................................................... 149
Ordering Information ............................................................................................................................................................................ 150
Disclaimers.................................................................................................................................................................................... 150
Contacts......................................................................................................................................................................................... 150
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Pin Diagram
FINAL
DATASHEET
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
SONSDHB
MSTSLVB
IC7
IC6
IC5
TO9
TO5
TO4
AGND3
VA3+
TO3
TO2
TO1
DGNDb
VDDb
VDDc
DGNDc
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
Figure 2 ACS8520 Pin Diagram Synchronous Equipment Timing Source for Stratum 3/4E/4 and SMC Systems
AGND
TRST
IC1
IC2
AGND1
VA1+
TMS
INTREQ
TCK
REFCLK
DGND1
VD1+
VD3+
DGND3
DGND2
VD2+
IC3
SRCSW
VA2+
AGND2
TDO
IC4
TDI
I1
I2
ACS8520
SONET/SDH SETS
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
RDY
PORB
ALE
RDB
WRB
CSB
A0
A1
A2
A3
A4
A5
A6
DGNDd
VDDd
UPSEL0
UPSEL1
UPSEL2
I14
I13
I12
I11
I10
I9
I8
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
VAMI+
TO8NEG
TO8POS
GND_AMI
FrSync
MFrSync
GND_DIFFa
VDD_DIFFa
TO6POS
TO6NEG
TO7POS
TO7NEG
GND_DIFFb
VDD_DIFFb
I5POS
I5NEG
I6POS
I6NEG
VDD5
SYNC2K
I3
I4
I7
DGNDa
VDDa
1
2
3
4
5
6
7
8
9
10
11
1
12
13
14
15
16
17
18
19
20
21
22
23
24
25
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Pin Description
FINAL
DATASHEET
Table 1 Power Pins
Pin Number
Symbol
I/O
Type
Description
12, 13,
16
VD1+, VD3+,
VD2+
P
-
Supply Voltage: Digital supply to gates in analog section, +3.3 Volts
±10%.
26
VAMI+
P
-
Supply Voltage: Digital supply to AMI output, +3.3 Volts ±10%.
33,
39
VDD_DIFFa,
VDD_DIFFb
P
-
Supply Voltage: Digital supply for differential ports, +3.3 Volts ±10%.
44
VDD5
P
-
Digital Supply for +5 Volts Tolerance to Input Pins. Connect to +5 Volts
(±10%) for clamping to +5 Volts. Connect to VDD for clamping to +3.3
Volts. Leave floating for no clamping, input pins tolerant up to +5.5
Volts.
50, 61,
85, 86
VDDa, VDDd,
VDDc, VDDb
P
-
Supply Voltage: Digital supply to logic, +3.3 Volts ±10%.
6
VA1+
P
-
Supply Voltage: Analog supply to clock multiplying PLL, +3.3 Volts ±10%.
19, 91
VA2+, VA3+
P
-
Supply Voltage: Analog supply to output PLLs, +3.3 Volts ±10%.
11, 14,
15,
DGND1, DGND3,
DGND2,
P
-
Supply Ground: Digital ground for components in PLLs.
49, 62,
84, 87
DGNDa, DGNDd,
DGNDc, DGNDb
P
-
Supply Ground: Digital ground for logic.
29
GND_AMI
P
-
Supply Ground: Digital ground for AMI output.
32,
38
GND_DIFFa,
GND_DIFFb
P
-
Supply Ground: Digital ground for differential ports.
1, 5,
20, 92
AGND, AGND1,
AGND2, AGND3
P
-
Supply Ground: Analog grounds.
Note...I = Input, O = Output, P = Power, TTLU = TTL input with pull-up resistor, TTLD = TTL input with pull-down resistor.
Table 2 Internally Connected Pins
Pin Number
3, 4, 17, 22,
96, 97, 98
Symbol
I/O
Type
IC1, IC2, IC3, IC4,
IC5, IC6, IC7
-
-
Revision 3.02/October 2005 © Semtech Corp.
Description
Internally Connected: Leave to Float.
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ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Table 3 Other Pins
Pin Number
Symbol
I/O
Type
Description
2
TRST
I
TTLD
JTAG Control Reset Input: TRST = 1 to enable JTAG Boundary Scan
mode. TRST = 0 for Boundary Scan stand-by mode, still allowing correct
device operation. If not used connect to GND or leave floating.
7
TMS
I
TTLU
JTAG Test Mode Select: Boundary Scan enable. Sampled on rising edge
of TCK. If not used connect to VDD or leave floating.
8
INTREQ
O
TTL/CMOS
9
TCK
I
TTLD
JTAG Clock: Boundary Scan clock input. If not used connect to GND or
leave floating.
10
REFCLK
I
TTL
Reference Clock: 12.800 MHz (refer to section headed Local Oscillator
Clock).
18
SRCSW
I
TTLD
Source Switching: Force Fast Source Switching. See “Fast External
Switching Mode-SCRSW Pin” on page 15.
21
TDO
O
TTL/CMOS
JTAG Output: Serial test data output. Updated on falling edge of TCK. If
not used leave floating.
23
TDI
I
TTLU
JTAG Input: Serial test data Input. Sampled on rising edge of TCK. If not
used connect to VDD or leave floating.
24
I1
I
AMI
Input Reference 1: Composite clock 64 kHz + 8 kHz.
25
I2
I
AMI
Input Reference 2: Composite clock 64 kHz + 8 kHz.
27
TO8NEG
O
AMI
Output Reference 8: Composite clock, 64 kHz + 8 kHz negative pulse.
28
TO8POS
O
AMI
Output Reference 8: Composite clock, 64 kHz + 8 kHz positive pulse.
30
FrSync
O
TTL/CMOS
Output Reference 10: 8 kHz Frame Sync output.
31
MFrSync
O
TTL/CMOS
Output Reference 11: 2 kHz Multi-Frame Sync output.
34,
35
TO6POS,
TO6NEG
O
LVDS/PECL
Output Reference 6: Programmable, default 38.88 MHz, default type
LVDS.
36,
37
TO7POS,
TO7NEG
O
PECL/LVDS
Output Reference 7: Programmable, default 19.44 MHz, default type
PECL.
40,
41
I5POS,
I5NEG
I
LVDS/PECL
Input Reference 5: Programmable, default 19.44 MHz, default type
LVDS.
42,
43
I6POS,
I6NEG
I
PECL/LVDS
Input Reference 6: Programmable, default 19.44 MHz, default type
PECL.
45
SYNC2K
I
TTLD
External Sync input: 2 kHz, 4 kHz or 8 kHz for frame alignment.
46
I3
I
TTLD
Input Reference 3: Programmable, default 8 kHz.
47
I4
I
TTLD
Input Reference 4: Programmable, default 8 kHz.
48
I7
I
TTLD
Input Reference 7: Programmable, default 19.44 MHz.
51
I8
I
TTLD
Input Reference 8: Programmable, default 19.44 MHz.
52
I9
I
TTLD
Input Reference 9: Programmable, default 19.44 MHz.
53
I10
I
TTLD
Input Reference 10: Programmable, default 19.44 MHz.
Revision 3.02/October 2005 © Semtech Corp.
Interrupt Request: Active High/Low software Interrupt output.
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DATASHEET
Table 3 Other Pins (cont...)
Pin Number
Symbol
I/O
Type
Description
54
I11
I
TTLD
Input Reference 11: Programmable, default (Master mode)
1.544/2.048 MHz, default (Slave mode) 6.48 MHz.
55
I12
I
TTLD
Input Reference 12: Programmable, default 1.544/2.048 MHz.
56
I13
I
TTLD
Input Reference 13: Programmable, default 1.544/2.048 MHz.
57
I14
I
TTLD
Input Reference 14: Programmable, default 1.544/2.048 MHz.
58 - 60
UPSEL(2:0)
I
TTLD
Microprocessor Select: Configures the interface for a particular
microprocessor type at reset.
63 - 69
A(6:0)
I
TTLD
Microprocessor Interface Address: Address bus for the microprocessor
interface registers. A(0) is SDI in Serial mode - output in EPROM mode
only. A(1) is CLKE in serial mode.
70
CSB
I
TTLU
Chip Select (Active Low): This pin is asserted Low by the microprocessor
to enable the microprocessor interface - output in EPROM mode only.
71
WRB
I
TTLU
Write (Active Low): This pin is asserted Low by the microprocessor to
initiate a write cycle. In Motorola mode, WRB = 1 for Read.
72
RDB
I
TTLU
Read (Active Low): This pin is asserted Low by the microprocessor to
initiate a read cycle.
73
ALE
I
TTLD
Address Latch Enable: This pin becomes the address latch enable from
the microprocessor. When this pin transitions from High to Low, the
address bus inputs are latched into the internal registers. ALE = SCLK in
Serial mode.
74
PORB
I
TTLU
Power-On Reset: Master reset. If PORB is forced Low, all internal states
are reset back to default values.
75
RDY
O
TTL/CMOS
76 - 83
AD(7:0)
IO
TTLD
88
TO1
O
TTL/CMOS
Output Reference 1: Programmable, default 6.48 MHz.
89
TO2
O
TTL/CMOS
Output Reference 2: Programmable, default 38.88 MHz.
90
TO3
O
TTL/CMOS
Output Reference 3: Programmable, default 19.44 MHz.
93
TO4
O
TTL/CMOS
Output Reference 4: Programmable, default 38.88 MHz.
94
TO5
O
TTL/CMOS
Output Reference 5: Programmable, default 77.76 MHz.
95
TO9
O
TTL/CMOS
Output Reference 9: 1.544/2.048 MHz, as per ITU G.783[9] BITS
requirements.
99
MSTSLVB
I
TTLU
Master/Slave Select: Sets the state of the Master/Slave selection
register, Reg. 34, Bit 1.
100
SONSDHB
I
TTLD
SONET or SDH Frequency Select: Sets the initial power-up state (or
state after a PORB) of the SONET/SDH frequency selection registers,
Reg. 34, Bit 2 and Reg. 38, Bit 5, Bit 6 and Reg. 64 Bit 4.When set Low,
SDH rates are selected (2.048 MHz etc.) and when set High, SONET
rates are selected (1.544 MHz etc.) The register states can be changed
after power-up by software.
Revision 3.02/October 2005 © Semtech Corp.
Ready/Data Acknowledge: This pin is asserted High to indicate the
device has completed a read or write operation.
Address/Data: Multiplexed data/address bus depending on the
microprocessor mode selection. AD(0) is SDO in Serial mode.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Introduction
FINAL
The ACS8520 is a highly integrated, single-chip solution
for the SETS function in a SONET/SDH Network Element,
for the generation of SEC and Frame/MultiFrame
Synchronization pulses. Digital Phase Locked Loop (DPLL)
and direct digital synthesis methods are used in the
device so that the overall PLL characteristics are very
stable and consistent compared to traditional analog
PLLs.
In Free-run mode, the ACS8520 generates a stable, lownoise clock signal at a frequency to the same accuracy as
the external oscillator, or it can be made more accurate
via software calibration to within ±0.02 ppm. In Locked
mode, the ACS8520 selects the most appropriate input
reference source and generates a stable, low-noise clock
signal locked to the selected reference. In Holdover mode,
the ACS8520 generates a stable, low-noise clock signal,
adjusted to match the last known good frequency of the
last selected reference source. A high level of phase and
frequency accuracy is made possible by an internal
resolution of up to 54 bits and internal Holdover accuracy
of up to 7.5 x 10-14 (instantaneous). In all modes, the
frequency accuracy, jitter and drift performance of the
clock meet the requirements of ITU G.736[7], G.742[8],
G783[9], G.812[10], G.813[11], G.823[13],G.824[14] and
Telcordia GR-253-CORE[17] and GR-1244-CORE[19].
The ACS8520 supports all three types of reference clock
source: recovered line clock, PDH network
synchronization timing, and node synchronization. The
ACS8520 generates independent T0 and T4 clocks, an 8
kHz Frame Synchronization clock and a 2 kHz Multi-Frame
Synchronization clock.
One key architectural advantage that the ACS8520 has
over traditional solutions is in the use of DPLL technology
for precise and repeatable performance over temperature
or voltage variations and between parts. The overall PLL
bandwidth, loop damping, pull-in range and frequency
accuracy are all determined by digital parameters that
provide a consistent level of performance. An Analog PLL
(APLL) takes the signal from the DPLL output and provides
a lower jitter output. The APLL bandwidth is set four orders
of magnitude higher than the DPLL bandwidth. This
ensures that the overall system performance still
maintains the advantage of consistent behavior provided
by the digital approach.
The DPLLs are clocked by the external Oscillator module
(TCXO or OCXO) so that the Free-run or Holdover
frequency stability is only determined by the stability of
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
the external oscillator module. This second key advantage
confines all temperature critical components to one well
defined and pre-calibrated module, whose performance
can be chosen to match the application; for example an
TCXO for Stratum 3 applications.
All performance parameters of the DPLLs are
programmable without the need to understand detailed
PLL equations. Bandwidth, damping factor and lock range
can all be set directly, for example. The PLL bandwidth
can be set over a wide range, 0.1 Hz to 70 Hz in 18 steps,
to cover all SONET/SDH clock synchronization
applications.
The ACS8520 supports protection. Two ACS8520 devices
can be configured to provide protection against a single
ACS8520 failure. The protection maintains alignment of
the two ACS8520 devices (Master and Slave) and
ensures that both ACS8520 devices maintain the same
priority table, choose the same reference input and
generate the T0 clock, the 8 kHz Frame Synchronization
clock and the 2 kHz Multi-Frame Synchronization clock
with the same phase. The ACS8520 includes a multistandard microprocessor port, providing access to the
configuration and status registers for device setup and
monitoring.
General Description
Overview
The following description refers to the Block Diagram
(Figure 1 on page 1).
The ACS8520 SETS device has 14 input clocks, generates
11 output clocks, and has a total of 55 possible output
frequencies. There are two main paths through the
device: T0 and T4. Each path has an independent DPLL
and APLL pair.
The T0 path is a high quality, highly configurable path
designed to provide features necessary for node timing
synchronization within a SONET/SDH network. The T4
path is a simpler and less configurable path designed to
give a totally independent path for internal equipment
synchronization. The device supports use of either or both
paths, either locked together or independent.
Of the 14 input references, two are AMI composite clock,
two are LVDS/PECL and the remaining ten are TTL/CMOS
compatible inputs. All the TTL/CMOS are 3 V and 5 V
compatible (with clamping if required by connecting the
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ACS8520 SETS
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FINAL
DATASHEET
VDD5 pin). The AMI inputs are ±1 V typically A.C. coupled.
Refer to the electrical characteristics section for more
information on the electrical compatibility and details.
Input frequencies supported range from 2 kHz to 155.52
MHz.
There are a number of features supported by the T0 path
that are not supported by the T4 path, although these can
also all be externally controlled by software.
Common E1, DS1, OC3 and sub-divisions are supported
as spot frequencies that the DPLLs will directly lock to.
Any input frequency, up to 100 MHz, that is a multiple of
8 kHz can also be locked to via an inbuilt programmable
divider.
z
An input reference monitor is assigned to each of the 14
inputs. The monitors operate continuously such that at all
times the status of all of the inputs to the device are
known. Each input can be monitored for both frequency
and activity, activity alone, or the monitors can be
disabled.
The frequency monitors have a “hard” (rejection) alarm
limit and a “soft” (flag only) alarm limit for monitoring
frequency, whilst the reference is still within its allowed
frequency band. Each input reference can be
programmed with a priority number allowing references to
be chosen according to the highest priority valid input. The
two paths (T0 and T4) have independent priorities to allow
completely independent operation of the two paths. Both
paths operate either automatic or external source
selection.
For automatic input reference selection, the T0 path has
a more complex state machine than the T4 path.
The T0 and T4 PLL paths support the following common
features:
z
z
z
z
z
z
z
z
Automatic source selection according to input
priorities and quality level
Different quality levels (activity alarm thresholds) for
each input
Variable bandwidth, lock range and damping factor
Direct PLL locking to common SONET/SDH input
frequencies or any multiple of 8 kHz
Automatic mode switching between Free-run, Locked
and Holdover states
Fast detection on input failure and entry into Holdover
mode (holds at the last good frequency value)
Frequency translation between input and output rates
via direct digital synthesis
High accuracy digital architecture for stable PLL
dynamics combined with an APLL for low jitter final
output clocks.
Revision 3.02/October 2005 © Semtech Corp.
The additional T0 features supported are:
z
z
z
z
z
z
z
Non-revertive mode
Phase Build-out on source switch (hit-less source
switching)
I/O phase offset control
Greater programmable bandwidth from 0.1 Hz to
70 Hz in 10 steps (T4 path programmable bandwidth
in 3 steps, 18, 35 and 70 Hz)
Noise rejection on low frequency input
Manual Holdover frequency control
Controllable automatic Holdover frequency filtering
Frame Sync pulse alignment.
Either the software or an internal state machine controls
the operation of the DPLL in the T0 path. The state
machine for the T4 path is very simple and cannot be
manually/externally controlled, however the overall
operation can be controlled by manual reference source
selection. One additional feature of the T4 path is the
ability to measure a phase difference between two inputs.
The T0 path DPLL always produces an output at
77.76 MHz to feed the APLL, regardless of the frequency
selected at the output pins. The T4 path can be operated
at a number of frequencies. This is to enable the
generation of extra output frequencies, which cannot be
easily related to 77.76 MHz. When the T4 path is selected
to lock to the T0 path, the T4 DPLL locks to the 8 kHz from
the T0 DPLL. This is because all of the frequencies of
operation of the T4 path can be divided to 8 kHz and this
will ensure synchronization of all the frequencies within
the two paths.
Both of the DPLLs’ outputs are connected to multiplying
and filtering APLLs. The outputs of these APLLs are
divided making a number of frequencies simultaneously
available for selection at the output clock ports. The
various combinations of DPLL, APLL and divider
configurations allow for generation of a comprehensive
set of frequencies, as listed in Table 14.
To synchronize the lower output frequencies when the T0
PLL is locked to a high frequency reference input, an
additional input is provided. The SYNC2K pin (pin 45) is
used to reset the dividers that generate the 2 kHz and
8 kHz outputs such that the output 2/8 kHz clocks are
lined up with the input 2 kHz. This synchronization
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method allows for example, a master and a slave device
to be in precise alignment.
The ACS8520 also supports Sync pulse references of
4 kHz or 8 kHz although in these cases frequencies lower
than the Sync pulse reference may not necessarily be in
phase.
Input Reference Clock Ports
Table 4 gives details of the input reference ports, showing
the input technologies and the range of frequencies
supported on each port; the default spot frequencies and
default priorities assigned to each port on power-up or by
reset are also shown. Note that SDH and SONET networks
use different default frequencies; the network type is pinselectable (using either the SONSDHB pin or via
software). Specific frequencies and priorities are set by
configuration.
For SONET, ip_sonsdhb = 1
z
For SDH, ip_sonsdhb = 0
Lock8K mode automatically sets the divider parameters
to divide the input frequency down to 8 kHz. Lock8K can
only be used on the supported spot frequencies (see
Table 4 Note(i)). Lock8k mode is enabled by setting the
Lock8k bit (Bit 6) in the appropriate
cnfg_ref_source_frequency register location. Using lower
frequencies for phase comparisons in the DPLL results in
a greater tolerance to input jitter.It is possible to choose
which edge of the input reference clock to lock to, by
setting 8K edge polarity (Bit 2 of Reg. 03, test_register1).
DivN Mode
In DivN mode, the divider parameters are set manually by
configuration (Bit 7 of the cnfg_ref_source_frequency
register), but must be set so that the frequency after
division is 8 kHz.
The DivN function is defined as:
DivN = “Divide by N+ 1”, i.e. it is the dividing factor used
for the division of the input frequency, and has a value of
(N+1) where N is an integer from 1 to 12499 inclusive.
SDH and SONET networks use different default
frequencies; the network type is selectable using the
cnfg_input_mode Reg. 34 Bit 2, ip_sonsdhb.
z
DATASHEET
Lock8K Mode
On power-up or by reset, the default will be set by the state
of the SONSDHB pin (pin 100). Specific frequencies and
priorities are set by configuration.
The frequency selection is programmed via the
cnfg_ref_source_frequency register (Reg. 20 - Reg. 2D).
Therefore, in DivN mode the input frequency can be
divided by any integer value between 2 to 12500.
Consequently, any input frequency which is a multiple of
8 kHz, between 8 kHz to 100 MHz, can be supported by
using DivN mode.
Note...Any reference input can be set to use DivN
independently of the frequencies and configurations of the
other inputs. However only one value of N is allowed, so all
inputs with DivN selected must be running at the same
frequency.
DivN Examples
Locking Frequency Modes
(a) To lock to 2.000 MHz:
There are three locking frequency modes that can be
configured: Direct Lock, Lock 8k and DivN.
(i)
Direct Lock Mode
(ii) To achieve 8 kHz, the 2 MHz input must be
divided by 250. So, if DivN = 250 = (N + 1)
then N must be set to 249. This is done by writing
F9 hex (249 decimal) to the DivN register pair
Reg. 46/47.
In Direct Lock Mode, the internal DPLL can lock to the
selected input at the spot frequency of the input, for
example 19.44 MHz performs the DPLL phase
comparisons at 19.44 MHz.
In Lock8K and DivN modes (and for special case of
155 MHz), an internal divider is used prior to the DPLL to
divide the input frequency before it is used for phase
comparisons in the DPLL.
Revision 3.02/October 2005 © Semtech Corp.
Set the cnfg_ref_source_frequency register to
10XX0000 (binary) to enable DivN, and set the
frequency to 8 kHz - the frequency required after
division. (XX = “Leaky Bucket” ID for this input).
(b) To lock to 10.000 MHz:
Page 10
(i)
The cnfg_ref_source_frequency register is set to
10XX0000 (binary) to set the DivN and the
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frequency to 8 kHz, the post-division frequency.
(XX = “Leaky Bucket” ID for this input).
(ii) To achieve 8 kHz, the 10 MHz input must be
divided by 1,250. So, if DivN, = 250 = (N+1)
then N must be set to 1,249. This is done by
writing 4E1 hex (1,249 decimal) to the DivN
register pair Reg. 46/47.
Direct Lock Mode 155 MHz.
The max frequency allowed for phase comparison is
77.76MHz, so for the special case of a 155 MHz input set
to Direct Lock Mode, there is a divide-by-two function
automatically selected to bring the frequency down to
within the limits of operation.
DATASHEET
PECL/LVDS/AMI Input Port Selection
The choice of PECL or LVDS compatibility is programmed
via the cnfg_differential_inputs register. Unused PECL
differential inputs should be fixed with one input High
(VDD) and the other input Low (GND), or set in LVDS mode
and left floating, in which case one input is internally
pulled High and the other Low.
An AMI port supports a composite clock, consisting of a
64 kHz AMI clock with 8 kHz boundaries marked by
deliberate violations of the AMI coding rules, as specified
in ITU recommendation G.703[6]. Departures from the
nominal pattern are detected within the ACS8520, and
may cause reference-switching if too frequent. See
section DC Characteristics: AMI Input/Output Port, for
more details. If the AMI port is unused, the pins (I1 and I2)
should be tied to GND.
Table 4 Input Reference Source Selection and Priority Table
Port Number
Channel
Number (Bin)
Input Port
Technology
Frequencies Supported
Default
Priority
I1
0001
AMI
64/8 kHz (composite clock, 64 kHz + 8 kHz)
Default (SONET): 64/8 kHz Default (SDH): 64/8 kHz
2
I2
0010
AMI
64/8 kHz (composite clock, 64 kHz + 8 kHz)
Default (SONET): 64/8 kHz Default (SDH): 64/8 kHz
3
I3
0011
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 8 kHz Default (SDH): 8 kHz
4
I4
0100
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 8 kHz Default (SDH): 8 kHz
5
I5
0101
LVDS/PECL LVDS Up to 155.52 MHz (see Note (ii))
default
Default (SONET): 19.44 MHz Default (SDH): 19.44 MHz
6
I6
0110
PECL/LVDS PECL Up to 155.52 MHz (see Note (ii))
default
Default (SONET): 19.44 MHz Default (SDH): 19.44 MHz
7
I7
0111
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 19.44 MHz Default (SDH): 19.44 MHz
8
I8
1000
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 19.44 MHz Default (SDH): 19.44 MHz
9
I9
1001
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 19.44 MHz Default (SDH): 19.44 MHz
10
I10
1010
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 19.44 MHz Default (SDH): 19.44 MHz
11
I11
1011
TTL/CMOS
Up to 100 MHz (see Note (i)) Default (Master) (SONET): 1.544 MHz Default
(Master) (SDH): 2.048 MHz Default (Slave) 6.48 MHz
12/1 (Note
(iii))
I12
1100
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 1.544 MHz Default (SDH): 2.048 MHz
13
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DATASHEET
Table 4 Input Reference Source Selection and Priority Table (cont...)
Port Number
Channel
Number (Bin)
Input Port
Technology
Frequencies Supported
Default
Priority
I13
1101
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 1.544 MHz Default (SDH): 2.048 MHz
14
I14
1110
TTL/CMOS
Up to 100 MHz (see Note (i))
Default (SONET): 1.544 MHz Default (SDH): 2.048 MHz
15
Notes: (i) TTL ports (compatible also with CMOS signals) support clock speeds up to 100 MHz, with the highest spot frequency being
77.76 MHz. The actual spot frequencies are: 2 kHz, 4 kHz, 8 kHz (and N x 8 kHz), 1.544 MHz (SONET)/2.048 MHz (SDH), 6.48 MHz,
19.44 MHz, 25.92 MHz, 38.88 MHz, 51.84 MHz, 77.76 MHz. SONET or SDH input rate is selected via Reg. 34 Bit 2, ip_sonsdhb).
(ii) PECL and LVDS ports support the spot clock frequencies listed above plus 155.52 MHz (and 311.04 MHz for TO6 only).
(iii) Input port I11 is set at priority 12 on the Master SETS IC and priority 1 on the Slave SETS IC, as default on power up (or PORB). The
default setup of Master or Slave I11 priority is determined by the MSTSLVB pin.
Clock Quality Monitoring
Clock quality is monitored and used to modify the priority
tables of the local and remote ACS8520 devices. The
following parameters are monitored:
1. Activity (toggling).
2. Frequency (this monitoring is only performed when
there is no irregular operation of the clock or loss of
clock condition).
In addition, input ports I1 and I2 carry AMI-encoded
composite clocks which are monitored by the AMIdecoder blocks. Loss of signal is declared by the decoders
when either the signal amplitude falls below +0.3 V or
there is no activity for 1 ms.
Any reference source that suffers a loss-of-activity or
clock-out-of-band condition will be declared as
unavailable.
Clock quality monitoring is a continuous process which is
used to identify clock problems. There is a difference in
dynamics between the selected clock and the other
reference clocks. Anomalies occurring on non-selected
reference sources affect only that source's suitability for
selection, whereas anomalies occurring on the selected
clock could have a detrimental impact on the accuracy of
the output clock.
Anomalies detected by the activity detector are integrated
in a Leaky Bucket Accumulator. Occasional anomalies do
not cause the Accumulator to cross the alarm setting
threshold, so the selected reference source is retained.
Persistent anomalies cause the alarm setting threshold to
be crossed and result in the selected reference source
being rejected.
Revision 3.02/October 2005 © Semtech Corp.
Anomalies on the currently locked-to input reference
clock, whether affecting signal purity or signal frequency,
could induce jitter or frequency offsets in the output clock,
leading to anomalous behavior. Anomalies on the
selected clock, therefore, have to be detected as they
occur and the phase locked loop must be temporarily
isolated until the clock is once again pure. The clock
monitoring process cannot be used for this because the
high degree of accuracy required dictates that the
process be slow. To achieve the immediacy required by
the phase locked loop requires an alternative
mechanism. The phase locked loop itself contains a fast
activity detector such that within approximately two
missing input clock cycles, a no-activity flag is raised and
the DPLL is frozen in Holdover mode. This flag can also be
read as the main_ref_failed bit (from Reg. 06, Bit 6) and
can be set to indicate a phase lost state by enabling
Reg. 73, Bit 6. With the DPLL in Holdover mode it is
isolated from further disturbances. If the input becomes
available again before the activity or frequency monitor
rejection alarms have been raised, then the DPLL will
continue to lock to the input, with little disturbance. In this
scenario, with the DPLL in the “locked” state, the DPLL
uses “nearest edge locking” mode (±180° capture)
avoiding cycle slips or glitches caused by trying to lock to
an edge 360° away, as would happen with traditional
PLLs.
Activity Monitoring
The ACS8520 has a combined inactivity and irregularity
monitor. The ACS8520 uses a Leaky Bucket Accumulator,
which is a digital circuit which mimics the operation of an
analog integrator, in which input pulses increase the
output amplitude but die away over time. Such integrators
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are used when alarms have to be triggered either by fairly
regular defect events, which occur sufficiently close
together, or by defect events which occur in bursts. Events
which are sufficiently spread out should not trigger the
alarm. By adjusting the alarm setting threshold, the point
at which the alarm is triggered can be controlled. The
point at which the alarm is cleared depends upon the
decay rate and the alarm clearing threshold.
On the alarm setting side, if several events occur close
together, each event adds to the amplitude and the alarm
will be triggered quickly; if events occur a little more
spread out, but still sufficiently close together to
overcome the decay, the alarm will be triggered
eventually. If events occur at a rate which is not sufficient
to overcome the decay, the alarm will not be triggered. On
the alarm clearing side, if no defect events occur for a
sufficient time, the amplitude will decay gradually and the
alarm will be cleared when the amplitude falls below the
alarm clearing threshold. The ability to decay the
amplitude over time allows the importance of defect
events to be reduced as time passes by. This means that,
in the case of isolated events, the alarm will not be set,
whereas, once the alarm becomes set, it will be held on
until normal operation has persisted for a suitable time
(but if the operation is still erratic, the alarm will remain
set). See Figure 3.
DATASHEET
There is one Leaky Bucket Accumulator per input channel.
Each Leaky Bucket can select from four Configurations
(Leaky Bucket Configuration 0 to 3). Each Leaky Bucket
Configuration is programmable for size, alarm set and
reset thresholds, and decay rate.
Each source is monitored over a 128 ms period. If, within
a 128 ms period, an irregularity occurs that is not deemed
to be due to allowable jitter/wander, then the
Accumulator is incremented.
The Accumulator will continue to increment up to the
point that it reaches the programmed Bucket size. The “fill
rate” of the Leaky Bucket is, therefore, 8 units/second.
The “leak rate” of the Leaky Bucket is programmable to
be in multiples of the fill rate (x 1, x 0.5, x 0.25 and
x 0.125) to give a programmable leak rate from
8 units/sec down to 1 unit/sec. A conflict between trying
to “leak” at the same time as a “fill” is avoided by
preventing a leak when a fill event occurs.
Disqualification of a non-selected reference source is
based on inactivity, or on an out-of-band result from the
frequency monitors. The currently selected reference
source can be disqualified for phase, frequency, inactivity
or if the source is outside the DPLL lock range. If the
currently selected reference source is disqualified, the
next highest priority, qualified reference source is
selected.
Figure 3 Inactivity and Irregularity Monitoring
Inactivities/Irregularities
Reference
Source
bucket_size
Leaky
Bucket
Response
upper_threshold
lower_threshold
Programmable Fall Slopes
(all programmable)
Alarm
F8530D_026Inact_Irreg_Mon_02
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Interrupts for Activity Monitors
The loss of the currently selected reference source will
eventually cause the input to be considered invalid,
triggering an interrupt. The time taken to raise this
interrupt is dependant on the Leaky Bucket Configuration
of the activity monitors. The fastest Leaky Bucket setting
will still take up to 128 ms to trigger the interrupt. The
interrupt caused by the brief loss of the currently selected
reference source is provided to facilitate very fast source
failure detection if desired. It is triggered after missing just
a couple of cycles of the reference source. Some
applications require the facility to switch downstream
devices based on the status of the reference sources. In
order to provide extra flexibility, it is possible to flag the
main_ref_failed interrupt (Reg. 06 Bit 6) on the pin TDO.
This is simply a copy of the status bit in the interrupt
register and is independent of the mask register settings.
The bit is reset by writing to the interrupt status register in
the normal way. This feature can be enabled and disabled
by writing to Reg. 48 Bit 6.
Leaky Bucket Timing
The time taken (in seconds) to raise an inactivity alarm on
a reference source that has previously been fully active
(Leaky Bucket empty) will be:
(cnfg_upper_threshold_n) / 8
where n is the number of the Leaky Bucket Configuration.
If an input is intermittently inactive then this time can be
longer. The default setting of cnfg_upper_threshold_n is
6, therefore the default time is 0.75 s.
The time taken (in seconds) to cancel the activity alarm on
a previously completely inactive reference source is
calculated, for a particular Leaky Bucket, as:
[2 (a) x (b - c)]/ 8
DATASHEET
acceptable frequency range measured with respect either
to the output clock or to the XO clock.
The sts_reference_sources out-of-band alarm for a
particular reference source is raised when the reference
source is outside the acceptable frequency range. With
the default register settings a soft alarm is raised if the
drift is outside ±11.43 ppm and a hard alarm is raised if
the drift is outside ±15.24 ppm. Both of these limits are
programmable from 3.8 ppm up to 61 ppm.
The ACS8520 DPLL has a programmable lock and
capture range frequency limit up to ±80 ppm (default is
±9.2 ppm).
Selection of Input Reference Clock Source
Under normal operation, the input reference sources are
selected automatically by an order of priority. But, for
special circumstances, such as chip or board testing, the
selection may be forced by configuration.
Automatic operation selects a reference source based on
its pre-defined priority and its current availability. A table
is maintained which lists all reference sources in the order
of priority. This is initially defined by the default
configuration and can be changed via the microprocessor
interface by the Network Manager. In this way, when all
the defined sources are active and valid, the source with
the highest programmed priority is selected but, if this
source fails, the next-highest source is selected, and so
on.
Restoration of repaired reference sources is handled
carefully to avoid inadvertent disturbance of the output
clock. For this, the ACS8520 has two modes of operation;
Revertive and Non-revertive.
In Revertive mode, if a re-validated (or newly validated)
source has a higher priority than the reference source
which is currently selected, a switch over will take place.
Many applications prefer to minimize the clock switching
events and choose Non-revertive mode.
where:
a = cnfg_decay_rate_n
b = cnfg_bucket_size_n
c = cnfg_lower_threshold_n
(where n = the number of the relevant Leaky
Bucket Configuration in each case).
In Non-revertive mode, when a re-validated (or newly
validated) source has a higher priority then the selected
source will be maintained. The re-validation of the
reference source will be flagged in the sts_sources_valid
register and, if not masked, will generate an interrupt.
The default setting is shown in the following:
[21 x (8 - 4)] /8 = 1.0 secs
Frequency Monitoring
Selection of the re-validated source can take place under
software control or if the currently selected source fails.
The ACS8520 performs frequency monitoring to identify
reference sources which have drifted outside the
To enable software control, the software should briefly
enable Revertive mode to effect a switch-over to the
Revision 3.02/October 2005 © Semtech Corp.
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higher priority source. When there is a reference available
with higher priority than the selected reference, there will
be NO change of reference source as long as the Nonrevertive mode remains on, and the currently selected
source is valid. A failure of the selected reference will
always trigger a switch-over regardless of whether
Revertive or Non-revertive mode has been chosen.
Also, in a Master/Slave redundancy-protection scheme,
the Slave device(s) must follow the Master device. The
alignment of the Master and Slave devices is part of the
protection mechanism. The availability of each source is
determined by a combination of local and remote
monitoring of each source. Each input reference source
supplied to each ACS8520 device is monitored locally and
the results are made available to other devices.
first then becomes valid again, it becomes the second
source on the first in, first out basis, and there will not be
a switch. If a third source with the same priority number
as the other two becomes valid, it joins the priority list on
the same first in, first out basis. There is no implied priority
based on the channel numbers. Revertive/Non-revertive
mode has no effect on sources with the same priority
value.
The input port I11 is also for the connection of the
synchronous clock of the T0 output of the Master device
(or the active-Slave device), to be used to align the T0
output with the Master (or active-Slave) device if this
device is acting in a subordinate-Slave or subordinateMaster role.
Ultra Fast Switching
Forced Control Selection
A configuration register, force_select_reference_source
Reg. 33, controls both the choice of automatic or forced
selection and the selection itself (when forced selection is
required). For Automatic choice of source selection, the 4
LSB bit value is set to all zeros or all ones (default). To
force a particular input (In), the Bit value is set to n (bin).
Forced selection is not the normal mode of operation, and
the force_select_reference_source variable is defaulted
to the all-ones value on reset, thereby adopting the
automatic selection of the reference source.
Automatic Control Selection
When an automatic selection is required, the
force_select_reference_source register LSB 4 bits must
be set to all zeros or all ones. The configuration registers,
cnfg_ref_selection_priority, held in the µP port block,
consist of seven, 8-bit registers organized as one 4-bit
register per input reference port. Each register holds a
4-bit value which represents the desired priority of that
particular port. Unused ports should be given the value,
0000, in the relevant register to indicate they are not to
be included in the priority table. On power-up, or following
a reset, the whole of the configuration file will be
defaulted to the values defined by Table 4. The selection
priority values are all relative to each other, with lowervalued numbers taking higher priorities. Each reference
source should be given a unique number; the valid values
are 1 to 15 (dec). A value of zero disables the reference
source. However if two or more inputs are given the same
priority number those inputs will be selected on a first in,
first out basis. If the first of two same priority number
sources goes invalid the second will be switched in. If the
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
A reference source is normally disqualified after the Leaky
Bucket monitor thresholds have been crossed. An option
for a faster disqualification has been implemented,
whereby if Reg. 48 Bit 5 (ultra_fast_switch) is set, then a
loss of activity of just a few reference clock cycles will set
the main_ref_failed alarm and cause a reference switch.
This can be configured (see Reg. 06, Bit 6) to cause an
interrupt to occur instead of, or as well as, causing the
reference switch.
The sts_interrupts register Reg. 06 Bit 6 (main_ref_failed)
is used to flag inactivity on the reference that the device
is locked to much faster than the activity monitors can
support. If Reg. 48 Bit 6 of the cnfg_monitors register
(los_flag_on_TDO) is set, then the state of this bit is driven
onto the TDO pin of the device.
Note...The flagging of the loss of the main reference failure on
TDO is simply allowing the status of the sts_interrupt bit
main_ref_failed (Reg. 06 Bit 6) to be reflected in the state of
the TDO output pin. The pin will, therefore, remain High until
the interrupt is cleared. This functionality is not enabled by
default so the usual JTAG functions can be used. When the
TDO output from the ACS8520 is connected to the TDI pin of
the next device in the JTAG scan chain, the implementation
should be such that a logic change caused by the action of the
interrupt on the TDI input should not effect the operation when
JTAG is not active.
Fast External Switching Mode-SCRSW Pin
Fast external switching mode, for fast switching between
inputs I3 or I5 and I4 or I6, can also be triggered directly
from a dedicated pin SRCSW (Figure 4), once the mode
has been initialized.
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The mode is initialized by either holding SRCSW pin High Modes of Operation
during reset (SRCSW must remain High for at least a
further 251 ms after PORB has gone High - see following
Note), or by writing to Reg. 48 Bit 4. After External
Protection Switching mode has been initialized, the value
on this pin directly selects either I3/I5 (SRCSW High) or
I4/I6 (SRCSW Low). If this mode is initialized at reset by
pulling the SRCSW pin High, then it configures the default
frequency tolerance of I3/I5 and I4/I6 to ±80 ppm
(Reg. 41 and Reg. 42) as opposed to the normal
frequency tolerance of ±9.2 ppm. Any of these registers
can be subsequently set by external software, if required.
Note...The 251 ms comprises 250 ms allowance for the
internal reset to be removed plus 1 ms allowance for APLLs to
start-up and become stable.
Selection of either input I3 or I5 is determined by the
Priority value of I3; if the programmed priority of I3 is 0,
then I5 is selected. Similarly, I6 is selected if the
programmed priority of I4 is 0.
Figure 4 I3/I5 and I4/I6 Switching
I3 Priority >0
SRCSW
I3
1
1
I5
0
T0 DPLL
I4
1
0
I6
0
I4 Priority >0
F8530D_006IPSWI3I4I5I6_01
When external protection switching is enabled, the device
will operate as a simple switch. All clock monitoring is
disabled and the DPLL will simply be forced to try to lock
on to the indicated reference source. Consequently the
device will always indicate “locked” state in the
sts_operating register (Reg. 09, Bits [2:0]).
Output Clock Phase Continuity on Source
Switchover
If either PBO is selected on (default), or, if DPLL frequency
limit is set to less than ±30 ppm or (±9.2 ppm default), the
device will always comply with GR-1244-CORE[19]
specification for Stratum 3 (maximum rate of phase
change of 81 ns/1.326 ms), for all input frequencies.
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
The ACS8520 has three primary modes of operation
(Free-run, Locked and Holdover) supported by three
secondary, temporary modes (Pre-locked, Lost-phase and
Pre-locked2). These are shown in the State Transition
Diagram for the T0 DPLL, Figure 5.
The ACS8520 can operate in Forced or Automatic control.
On reset, the ACS8520 reverts to Automatic Control,
where transitions between states are controlled
completely automatically. Forced Control can be invoked
by configuration, allowing transitions to be performed
under external control. This is not the normal mode of
operation, but is provided for special occasions such as
testing, or where a high degree of hands-on control is
required.
Free-run Mode
The Free-run mode is typically used following a power-onreset or a device reset before network synchronization
has been achieved. In the Free-run mode, the timing and
synchronization signals generated from the ACS8520 are
based on the 12.800 MHz clock frequency provided from
the external oscillator and are not synchronized to an
input reference source. By default, the frequency of the
output clock is a fixed multiple of the frequency of the
external oscillator, and the accuracy of the output clock is
equal to the accuracy of the oscillator. However the
external oscillator frequency can be calibrated to improve
its accuracy by a software calibration routine using
register cnfg_nominal_frequency (Reg. 3C and 3D). For
example a 500 ppm offset crystal could be made to look
like one accurate to within ±0.02 ppm.
The transition from Free-run to Pre-locked occurs when
the ACS8520 selects a reference source.
Pre-locked Mode
The ACS8520 will enter the Locked state in a maximum of
100 seconds, as defined by GR-1244-CORE[19]
specification, if the selected reference source is of good
quality. If the device cannot achieve lock within 100
seconds, it reverts to Free-run mode and another
reference source is selected.
Locked Mode
The Locked mode is entered from Pre-locked, Pre-locked2
or Phase-lost mode when an input reference source has
been selected and the DPLL has locked. The DPLL is
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considered to be locked when the phase loss/lock
detectors (see “Phase Lock/Loss Detection” on page 21)
indicate that the DPLL has remained in phase lock
continuously for at least one second. When the ACS8520
is in Locked mode, the output frequency and phase tracks
that of the selected input reference source.
Lost-phase Mode
Lost-phase mode is used whenever the phase loss/lock
detectors (see “Phase Lock/Loss Detection” on page 21)
indicate that the DPLL has lost phase lock. The DPLL will
still be trying to lock to the input clock reference, if it
exists. If the Leaky Bucket Accumulator calculates that
the anomaly is serious, the device disqualifies the
reference source. If the device spends more than 100
seconds in Lost-phase mode, the reference is disqualified
and a phase alarm is raised on it. If the reference is
disqualified, one of the following transitions takes place:
1. Go to Pre-locked2;
- If a known good stand-by source is available.
2. Go to Holdover;
- If no stand-by sources are available.
Holdover Mode
Holdover mode is the operating condition the device
enters when its currently selected input source becomes
invalid, and no other valid replacement source is
available. In this mode, the device resorts to using stored
frequency data, acquired when the input reference source
was still valid, to control its output frequency.
In Holdover mode, the ACS8520 provides the timing and
synchronization signals to maintain the Network Element
but is not phase locked to any input reference source. Its
output frequency is determined by an averaged version of
the DPLL frequency when last in the Locked Mode.
Holdover can be configured to operate in either:
z
Automatic mode
(Reg. 34 Bit 4, cnfg_input_mode: man_holdover set
Low), or
z
Manual mode
(Reg. 34 Bit 4, cnfg_input_mode: man_holdover set
High).
Automatic Mode
In Automatic mode, the device can be configured to
operate using either:
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
z
Averaged - (Reg. 40 Bit 7, cnfg_holdover_modes,
auto_averaging: set High), or
z
Instantaneous - (Reg. 40 Bit 7, cnfg_holdover_modes,
auto_averaging: set Low).
Averaged
In the Averaged mode, the frequency (as reported by
sts_current_DPLL_frequency, see Reg. 0C, Reg. 0D and
Reg. 07) is filtered internally using an Infinite Impulse
Response filter, which can be set to either:
z
z
Fast - (Reg. 40 Bit 6, cnfg_holdover_modes,
fast_averaging: set High), giving a -3 dB filter
response point corresponding to a period of
approximately eight minutes, or
Slow - (Reg. 40 Bit 6, cnfg_holdover_modes,
fast_averaging: set Low) giving a -3 dB filter response
point corresponding to a period of approximately 110
minutes.
Instantaneous
In Instantaneous mode, the DPLL freezes at the frequency
it was operating at the time of entering Holdover mode. It
does this by using only its internal DPLL integral path
value (as reported in Reg. 0C, 0D, and 07) to determine
output frequency. The DPLL proportional path is not used
so that any recent phase disturbances have a minimal
effect on the Holdover frequency. The integral value used
can be viewed as a filtered version of the locked output
frequency over a short period of time. The period being in
inverse proportion to the DPLL bandwidth setting.
Manual Mode
(Reg. 34 Bit 4, cnfg_input_mode, man_holdover set
High.) The Holdover frequency is determined by the value
in register cnfg_holdover_frequency (Reg. 3E, Reg. 3F,
and part of Reg. 40). This is a 19-bit signed number, with
a LSB resolution of 0.0003068 ppm, which gives an
adjustment range of ±80 ppm. This value can be derived
from a reading of register sts_current_DPLL_frequency
(Reg. 0D, Reg. 0C and Reg. 07), which gives, in the same
format, an indication of the current output frequency
deviation, which would be read when the device is locked.
If required, this value could be read by external software
and averaged over time. The averaged value could then
be fed to the cnfg_holdover_frequency register, ready for
setting the averaged frequency value when the device
enters Holdover mode. The sts_current_DPLL_frequency
value is internally derived from the Digital Phase Locked
Loop (DPLL) integral path, which represents a short-term
average measure of the current frequency, depending on
the locked loop bandwidth (Reg. 67) selected.
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DATASHEET
Figure 5 Automatic Mode Control State Diagram (T0 DPLL)
(1) Reset
Free-run
select ref
(state 001)
(2) all refs evaluated
&
at least one ref valid
(3) no valid standby ref
&
(main ref invalid
or out of lock > 100s
Reference sources are flagged as valid when
active, in-band and have no phase alarm set.
(4) valid standby ref
&
[main ref invalid or
(higher-priority ref valid
& in revertive mode) or
out of lock > 100s]
All sources are continuously checked for
activity and frequency
Pre-locked
wait for up to 100s
(state 110)
Only the main source is checked for phase.
A phase lock alarm is only raised on a
reference when that reference has lost phase
whilst being used as the main reference. The
micro-processor can reset the phase lock
alarm.
(5) selected ref
phase locked
A source is considered to have phase locked
when it has been continuously in phase lock
for between 1 and 2 seconds.
Locked
keep ref
(state 100)
(6) no valid standby ref
&
main ref invalid
(10) selected source
phase locked
(8) phase
regained
(9) valid standby ref
within 100s
&
[main ref invalid or
(higher priority ref valid
& in revertive mode)]
Pre-locked2
wait for up to 100s
(state 101)
(12) valid standby ref
&
(main ref invalid
or out of lock >100s)
(15) valid standby ref
&
[main ref invalid or
(higher-priority ref valid
& in revertive mode) or
out of lock >100s]
(7) phase lost
on main ref
(11) no valid standby ref
&
Lost-phase
(main ref invalid
wait for up to 100s
or out of lock >100s)
(state 111)
Holdover
select ref
(state 010)
(13) no valid standby ref
&
(main ref invalid
or out of lock >100s)
(14) all refs evaluated
&
at least one ref valid
F8530D_018AutoModeContStateDia_02
Note...The state diagram above is for T0 DPLL only, and the 3-bit state value refers to the register sts_operating Reg. 09 Bits
[2:0] T0_DPLL_operating _mode. By contrast, the T4 DPLL has only automatic operation and can be in one of only two
possible states: “Instantaneous Automatic Holdover” with zero frequency offset (its start-up state), or “Locked”. The T4 DPLL
states are not configurable by the User and there is no “Free-run” state.
Revision 3.02/October 2005 © Semtech Corp.
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It is also possible to combine the internal averaging filters
with some additional software filtering. For example the
internal fast filter could be used as an anti-aliasing filter
and the software could further filter this before
determining the actual Holdover frequency. To support
this feature, a facility to read out the internally averaged
frequency has been provided. By setting Reg. 40, Bit 5,
cnfg_holdover_modes, read_average, the value read
back from the cnfg_holdover_frequency register will be
the filtered value. The filtered value is available
regardless of what actual Holdover mode is selected.
Clearly this results in the register not reading back the
data that was written to it.
Example: Software averaging to eliminate temperature drift.
Select Manual Holdover mode by setting Reg. 34 Bit 4,
cnfg_input_mode, man_holdover High.
Select Fast Holdover Averaging mode by setting Reg. 40
Bit 6, cnfg_holdover_modes, auto_averaging High and
Reg. 40 Bit 7 High.
Select to be able to read back filtered output by setting
Reg. 40 Bit 5, cnfg_holdover_modes, read_average High.
Software periodically reads averaged value from the
cnfg_holdover_frequency register and the temperature
(not supplied from ACS8520). Software processes
frequency and temperature and places data in software
look-up table or other algorithm. Software writes back
appropriate averaged value into the
cnfg_holdover_frequency register.
Once Holdover mode is entered, software periodically
updates the cnfg_holdover_frequency register using the
temperature information (not supplied from ACS8520).
Mini-holdover Mode
Holdover mode so far described refers to a state to which
the internal state machine switches as a result of activity
or frequency alarms, and this state is reported in Reg. 09.
To avoid the DPLL’s frequency being pulled off as a result
of a failed input, then the DPLL has a fast mechanism to
freeze its current frequency within one or two cycles of the
input clock source stopping. Under these circumstances
the DPLL enters Mini-holdover mode; the Mini-holdover
frequency used being determined by Reg. 40, Bits [4:3],
cnfg_holdover_modes, mini_holdover_mode.
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
Mini-holdover mode only lasts until one of the following
happens:
z
A new source has been selected, or
z
The state machine enters Holdover mode, or
z
The original fault on the input recovers.
External Factors Affecting Holdover Mode
If the external TCXO/OCXO frequency is varying due to
temperature fluctuations in the room, then the
instantaneous value can be different from the average
value, and then it may be possible to exceed the 0.05
ppm limit (depending on how extreme the temperature
fluctuations are). It is advantageous to shield the
TCXO/OCXO to slow down frequency changes due to drift
and external temperature fluctuations.
The frequency accuracy of Holdover mode has to meet the
ITU-T, ETSI and Telcordia performance requirements. The
performance of the external oscillator clock is critical in
this mode, although only the frequency stability is
important - the stability of the output clock in Holdover is
directly related to the stability of the external oscillator.
Pre-locked2 Mode
This state is very similar to the Pre-Locked state. It is
entered from the Holdover state when a reference source
has been selected and applied to the phase locked loop.
It is also entered if the device is operating in Revertive
mode and a higher-priority reference source is restored.
Upon applying a reference source to the phase locked
loop, the ACS8520 will enter the Locked state in a
maximum of 100 seconds, as defined by GR-1244CORE[19] specification, if the selected reference source is
of good quality.
If the device cannot achieve lock within 100 seconds, it
reverts to Holdover mode and another reference source is
selected.
DPLL Architecture and Configuration
A Digital PLL gives a stable and consistent level of
performance that can be easily programmed for different
dynamic behavior or operating range. It is not affected by
operating conditions or silicon process variations. Digital
synthesis is used to generate all required SONET/SDH
output frequencies. The digital logic operates at
204.8 MHz that is multiplied up from the external
12.800 MHz oscillator module. Hence the best resolution
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of the output signals from the DPLL is one 204.8 MHz
cycle or 4.9 ns.
Additional resolution and lower final output jitter is
provided by a de-jittering Analog PLL that reduces the
4.9 ns p-p jitter from the digital down to 500 ps p-p and
60 ps RMS as typical final outputs measured broadband
(from 10 Hz to 1 GHz).
This arrangement combines the advantages of the
flexibility and repeatability of a DPLL with the low jitter of
an APLL. The DPLLs in the ACS8520 are uniquely very
programmable for all PLL parameters of bandwidth (from
0.1 Hz up to 70 Hz), damping factor (from 1.2 to 20),
frequency acceptance and output range (from 0 to
80 ppm, typically 9.2 ppm), input frequency (12 common
SONET/SDH spot frequencies) and input-to-output phase
offset (in 6 ps steps up to 200 ns). There is no
requirement to understand the loop filter equations or
detailed gain parameters since all high level factors such
as overall bandwidth can be set directly via registers in
the microprocessor interface. No external critical
components are required for either the internal DPLLs or
APLLs, providing another key advantage over traditional
discrete designs.
The T4 DPLL is similar in structure to the T0 DPLL, but
since the T4 is only providing a clock synthesis and input
to output frequency translation function, with no defined
requirement for jitter attenuation or input phase jump
absorption, then its bandwidth is limited to the high end
and the T4 does not incorporate many of the Phase Buildout and adjustment facilities of the T0 DPLL.
TO DPLL Main Features
z
Two programmable DPLL bandwidth controls (Locked
and Acquisition bandwidth), each with 10 steps from
0.1 Hz to 70 Hz
z
Programmable damping factor: For optional faster
locking and peaking control. Factors = 1.2, 2.5, 5, 10
or 20
z
Multiple phase lock detectors
z
Input to output phase offset adjustment
(Master/Slave), ±200 ns, 6 ps resolution step size
z
PBO phase offset on source switching - disturbance
down to ±5 ns
z
Multi-cycle phase detection and locking,
programmable up to ±8192 UI - improves jitter
tolerance in direct lock mode
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
z
Holdover frequency averaging with a choice of
averaging times: 8 minutes or 110 minutes and value
can be read out
z
Multiple E1 and DS1 outputs supported
z
Low jitter MFrSync (2 kHz) and FrSync (8 kHz) outputs.
T4 DPLL Main Features
z
A single programmable DPLL bandwidth control:
18 Hz, 35 Hz, or 70 Hz
z
Programmable damping factor: For optional faster
locking and peaking control. Factors = 1.2, 2.5, 5, 10
or 20
z
Multiple phase lock detectors
z
Multi-cycle phase detection and locking,
programmable up to ±8192 UI - improves jitter
tolerance in direct lock mode
z
DS3/E3 support (44.736 MHz / 34.368 MHz) at same
time as OC-N rates from T0
z
Low jitter E1/DS1 options at same time as OC-N rates
from T0
z
Frequencies of n x E1/DS1 including 16 and 12 x E1,
and 16 and 24 x DS1 supported
z
Low jitter MFrSync (2 kHz) and FrSync (8 kHz) outputs
z
Can use the T4 DPLL as an Independent FrSync DPLL
z
Can use the phase detector in T4 DPLL to measure
the input phase difference between two inputs.
The structure of the T0 and T4 PLLs are shown later in
Figure 11 in the section on output clock ports. That
section also details how the DPLLs and particular output
frequencies are configured. The following sections detail
some component parts of the DPLL.
TO DPLL Automatic Bandwidth Controls
In Automatic Bandwidth Selection mode (Reg. 3B Bit 7),
the T0 DPLL bandwidth setting is selected automatically
from the Acquisition Bandwidth or Locked Bandwidth
configurations programmed in cnfg_T0_DPLL_acq_bw
Reg. 69 and cnfg_T0_DPLL_locked_bw Reg. 67
respectively. If this mode is not selected, the DPLL
acquires and locks using only the bandwidth set by .
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Phase Detectors
A Phase and Frequency detector is used to compare input
and feedback clocks. This operates at input frequencies
up to 77.76 MHz. The whole DPLL can operate at spot
frequencies from 2 kHz up to 77.76 MHz (155.52 MHz is
internally divided down to 77.76 MHz). A common
arrangement however is to use Lock8k mode (See
Reg. 22 to 2D, Bit 6) where all input frequencies are
divided down to 8 kHz internally. Marginally better MTIE
figures may be possible in direct lock mode due to more
regular phase updates. This direct locking capability is
one of the unique features of the ACS8520.
A patented multi-phase detector is used in order to give
an infinitesimally small input phase resolution combined
with large jitter tolerance. The following phase detectors
are used:
DATASHEET
An additional control (Reg. 74 Bit 5) enables the multiphase detector value to be used in the final phase value
as part of the DPLL loop. When enabled by setting High,
the multi cycle phase value will be used in the loop and
gives faster pull in (but more overshoot). The
characteristics of the loop will be similar to Lock8k mode
where again large input phase differences contribute to
the loop dynamics. Setting the bit Low only uses a max
figure of 360 degrees in the loop and will give slower pullin but gives less overshoot. The final phase position that
the loop has to pull in to is still tracked and remembered
by the multi-cycle phase detector in either case.
Phase Lock/Loss Detection
Phase lock/loss detection is handled in several ways.
Phase loss can be triggered from:
z
Phase and frequency detector (±360° or ±180°
range)
z
The fine phase lock detector, which measures the
phase between input and feedback clock
z
An Early/ Late Phase detector for fine resolution
z
z
A multi-cycle phase detector for large input jitter
tolerance (up to 8191 UI), which captures and
remembers phase differences of many cycles
between input and feedback clocks.
The coarse phase lock detector, which monitors whole
cycle slips
z
Detection that the DPLL is at min or max frequency
z
Detection of no activity on the input.
The phase detectors can be configured to be immune to
occasional missing input clock pulses by using nearest
edge detection (±180° capture) or the normal ±360°
phase capture range which gives frequency locking. The
device will automatically switch to nearest edge locking
when the multi-UI phase detector is not enabled, and the
other phase detectors have detected that phase lock has
been achieved. It is possible to disable the selection of
nearest edge locking via Reg. 03 Bit 6 set to 1. In this
setting, frequency locking will always be enabled.
The balance between the first two types of phase detector
employed can be adjusted via registers 6A to 6D. The
default settings should be sufficient for all modes.
Adjustment of these settings affects only small signal
overshoot and bandwidth.
The multi-cycle phase detector is enabled via Reg. 74,
Bit 6 set to 1 and the range is set in exponentially
increasing steps from ±1 UI, 3 UI, 7 UI, 15 UI … up to
8191 UI via Reg. 74, Bits [3:0]. When this detector is
enabled it keeps a track of the correct phase position over
many cycles of phase difference to give excellent jitter
tolerance. This provides an alternative to switching to
Lock8k mode as a method of achieving high jitter
tolerance.
Revision 3.02/October 2005 © Semtech Corp.
Each of these sources of phase loss indication is
individually enabled via register bits (see Reg. 73, 74 and
4D). Phase lock or lost is used to determine whether to
switch to nearest edge locking and whether to use
acquisition or normal bandwidth settings for the DPLL.
Acquisition bandwidth is used for faster pull in from an
unlocked state.
The coarse phase lock detector detects phase differences
of n cycles between input and feedback clocks, where n is
set by Reg. 74, Bits [3:0]; the same register that is used
for the coarse phase detector range, since these
functions go hand in hand. This detector may be used in
the case where it is required that a phase loss indication
is not given for reasonable amounts of input jitter and so
the fine phase loss detector is disabled and the coarse
detector is used instead.
Damping Factor Programmability
The DPLL damping factor is set by default to provide a
maximum wander gain peak of around 0.1 dB. Many of
the specifications (e.g. GR-1244-CORE[19], G.812[10] and
G.813[11]) specify a wander transfer gain of less than
0.2 dB. GR-253[17] specifies jitter (not wander) transfer of
less than 0.1 dB. To accommodate the required levels of
transfer gain, the ACS8520 provides a choice of damping
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factors, with more choice given as the bandwidth setting
increases into the frequency regions classified as jitter.
Table 5 shows which damping factors are available for
selection at the different bandwidth settings, and what
the corresponding jitter transfer approximate gain peak
will be.
Table 5 Available Damping Factors for different DPLL
Bandwidths, and associated Jitter Peak Values
Bandwidth
Reg. 6B [2:0]
Damping
Gain Peak/ dB
Factor selected
DATASHEET
Table 6 ITU and ETSI Specification
Parameter
Value
Tolerance
±4.6 ppm over 20 year lifetime
Drift
(Frequency Drift
over supply
voltage range of
+2.7 V to +3.3 V)
±0.05 ppm/15 seconds @ constant temp.
±0.01 ppm/day @ constant temp.
±1 ppm over temp. range 0 to +70°C
Telcordia specifications are somewhat tighter, requiring a
non-temperature-related drift of less than 40 ppb per day
and a drift of 280 ppb over the temperature range 0 to
+50°C. Please contact Semtech for information on crystal
oscillator suppliers
0.1 Hz to 4 Hz
1, 2, 3, 4, 5
5
0.1
8 Hz
1
2.5
0.2
2, 3, 4, 5
5
0.1
1
1.2
0.4
2
2.5
0.2
3, 4, 5
5
0.1
Tolerance
±4.6 ppm over 20 year lifetime
1
1.2
0.4
±0.05 ppm/15 seconds @ constant temp.
2
2.5
0.2
3
5
0.1
Drift
(Frequency Drift
over supply
voltage range of
+2.7 V to +3.3 V)
4, 5
10
0.06
1
1.2
0.4
2
2.5
0.2
3
5
0.1
4
10
0.06
5
20
0.03
18 Hz
35 Hz
70 Hz
Table 7 Telcordia GR-1244 CORE Specification
Parameter
±0.04 ppm/15 seconds @ constant temp.
±0.28 ppm/over temp. range 0 to +50°C
Crystal Frequency Calibration
Local Oscillator Clock
The Master system clock on the ACS8520 should be
provided by an external clock oscillator of frequency
12.800 MHz. The clock specification is important for
meeting the ITU/ETSI and Telcordia performance
requirements for Holdover mode. ITU and ETSI
specifications permit a combined drift characteristic, at
constant temperature, of all non-temperature-related
parameters, of up to 10 ppb per day. The same
specifications allow a drift of 1 ppm over a temperature
range of 0 to +70°C.
Revision 3.02/October 2005 © Semtech Corp.
Value
The absolute crystal frequency accuracy is less important
than the stability since any frequency offset can be
compensated by adjustment of register values in the IC.
This allows for calibration and compensation of any
crystal frequency variation away from its nominal value.
±50 ppm adjustment would be sufficient to cope with
most crystals, in fact the range is an order of magnitude
larger due to the use of two 8-bit register locations. The
setting of the conf_nominal_frequency register allows for
this adjustment. An increase in the register value
increases the output frequencies by 0.0196229 ppm for
each LSB step.
The default register value (in decimal) = 39321
(9999 hex) = 0 ppm offset. The minimum to maximum
offset range of the register is 0 to 65535 dec, giving an
adjustment range of -771 ppm to +514 ppm of the output
frequencies, in 0.0196229 ppm steps.
Example: If the crystal was oscillating at 12.800 MHz +
5 ppm, then the calibration value in the register to give a
- 5 ppm adjustment in output frequencies to compensate
for the crystal inaccuracy, would be:
39321 - (5/0.0196229) = 39066 (dec) = 989A (hex).
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Output Wander
Typical measurements for the ACS8520 are shown in
Figure 6, for Locked mode operation. Figure 7 shows a
typical measurement of Phase Error accumulation in
Holdover mode operation.
Wander and jitter present on the output clocks are
dependent on:
z
The magnitudes of wander and jitter on the selected
input reference clock (in Locked mode)
z
The internal wander and jitter transfer characteristic
(in Locked mode)
z
The jitter on the local oscillator clock
z
The wander on the local oscillator clock (in Holdover
mode).
Wander and jitter are treated in different ways to reflect
their differing impacts on network design. Jitter is always
strongly attenuated, whilst wander attenuation can be
varied to suit the application and operating state. Wander
and jitter attenuation is performed using a digital phase
locked loop (DPLL) with a programmable bandwidth. This
gives a transfer characteristic of a low pass filter, with a
programmable pole. It is sometimes necessary to change
the filter dynamics to suit particular circumstances - one
example being when locking to a new source, the filter can
be opened up to reduce locking time and can then be
tightened again to remove wander. A change between
different bandwidths for locking and for acquisition is
handled automatically within the ACS8520.
There may be a phase shift across the ACS8520 between
the selected input reference source and the output clock
over time, mainly caused by frequency wander in the
external oscillator module. Higher stability XOs will give
better performance for MTIE. The oscillator becomes
more critical at DPLL bandwidth near to or below 0.1 Hz
since the rate of change of the DPLL may be slow
compared to the rate of change of the oscillator
frequency. Shielding of the OCXO or TCXO can further slow
down the rate of change of temperature and hence
frequency, thus improving output wander performance.
The phase shift may vary over time but will be constrained
to lie within specified limits. The phase shift is
characterized using two parameters, MTIE (Maximum
Time Interval Error) and TDEV (Time Deviation) which,
although being specified in all relevant specifications,
differ in acceptable limits in each one.
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
The required performance for phase variation during
Holdover is specified in several ways and depends on the
relevant specification (See “References” on page 146),
for example:
1. ETSI ETS-300 462-5[4], Section 9.1, requires that the
short-term phase error during switchover (i.e. Locked
to Holdover to Locked) be limited to an accumulation
rate no greater than 0.05 ppm during a 15 second
interval.
2. ETSI ETS-300 462-5[4], Section 9.2, requires that the
long-term phase error in the Holdover mode should
not exceed
{(a1 + a2)S + 0.5bS2 + c}
where
a1 = 50 ns/s (allowance for initial frequency offset)
a2 = 2000 ns/s (allowance for temperature variation)
b = 1.16x10-4 ns/s2 (allowance for ageing)
c = 120 ns (allowance for entry into Holdover mode).
S = Elapsed time (s) after loss of external ref. input
3. ANSI Tin1.101-1999[1], Section 8.2.2, requires that
the phase variation be limited so that no more than
255 slips (of 125 µs each) occur during the first day of
Holdover. This requires a frequency accuracy better
than:
((24x60x60)+(255x125µs))/(24x60x60) = 0.37 ppm
Temperature variation is not restricted, except to
within the normal bounds of 0 to 50°C.
4. Telcordia GR-1244-CORE[19], Section 5.2, shows that
an initial frequency offset of 50 ppb is permitted on
entering Holdover, whilst a drift over temperature of
280 ppb is allowed; an allowance of 40 ppb is
permitted for all other effects.
5. ITU G.822[12], Section 2.6, requires that the slip rate
during category (b) operation (interpreted as being
applicable to Holdover mode operation) be limited to
less than 30 slips (of 125 µs each) per hour.
Page 23
((60 x 60) + (30 x 125 µs))/(60 x 60)) = 1.042 ppm
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Figure 6 Maximum Time Interval Error and Time Deviation of T0 PLL Output Port
MTIE for G.813 option 1,
Constant temperature wander limit
TDEV for G.813 option 1,
Constant temperature wander limit
F8530D_027MtieTdevCombF6_01
Figure 7 Phase Error Accumulation of T0 PLL Output Port in Holdover Mode
10000000
Phase Error (ns)
1000000
Permitted Phase Error Limit
100000
10000
1000
100
Typical measurement, 25°C constant temperature
1000
Revision 3.02/October 2005 © Semtech Corp.
10000
Page 24
100000
Observation interval (s)
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Jitter and Wander Transfer
The ACS8520 has a programmable jitter and wander
transfer characteristic. This is set by the DPLL bandwidth.
The -3 dB jitter transfer attenuation point can be set in the
range from 0.1 Hz to 70 Hz in 10 steps. The wander and
jitter transfer characteristic is shown in Figure 8. Wander
on the local oscillator clock will not have a significant
effect on the output clock whilst in Locked mode, provided
that the DPLL bandwidth is set high enough so that the
DPLL can compensate quickly enough for any frequency
changes in the crystal.
In Free-run or Holdover mode wander on the crystal is
more significant. Variation in crystal temperature or
supply voltage both cause drifts in operating frequency,
as does ageing. These effects must be limited by careful
selection of a suitable component for the local oscillator,
as specified in the section See Local Oscillator Clock.
Phase Build-out
Phase Build-out (PBO) is the function to minimize phase
transients on the output SEC clock during input reference
switching. If the currently selected input reference clock
source is lost (due to a short interruption, out of frequency
detection, or complete loss of reference) the second, next
highest priority reference source will be selected, and a
PBO event triggered.
[11]
DATASHEET
states that the maximum allowable shortITU-T G.813
term phase transient response, resulting from a switch
from one clock source to another, with Holdover mode
entered in between, should be a maximum of 1 µs over a
15 second interval. The maximum phase transient or
jump should be less than 120 ns at a rate of change of
less than 7.5 ppm and the Holdover performance should
be better than 0.05 ppm. The ACS8520 performance is
well within this requirement. The typical phase
disturbance on clock reference source switching will be
less than 5 ns on the ACS8520.
When a PBO event is triggered, the device enters a
temporary Holdover state. When in this temporary state,
the phase of the input reference is measured, relative to
the output. The device then automatically accounts for
any measured phase difference and adds the appropriate
phase offset into the DPLL to compensate. Following a
PBO event, whatever the phase difference on change of
input, the output phase transient is minimized to be no
greater than 5 ns.
On the ACS8520, PBO can be enabled, disabled or frozen
using the microprocessor interface. By default, it is
enabled. When PBO is enabled, PBO can also be frozen (at
the current offset setting). The device will then ignore any
further PBO events occurring on any subsequent
Figure 8 Sample of Wander and Jitter Measured Transfer Characteristics
Revision 3.02/October 2005 © Semtech Corp.
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reference switch, and maintain the current phase offset.
If PBO is disabled while the device is in the Locked mode,
there may be a phase shift on the output SEC clocks as
the DPLL locks back to 0 degrees phase error. The rate of
phase shift will depend on the programmed bandwidth.
Enabling PBO whilst in the Locked stated will also trigger
a PBO event.
PBO Phase Offset
In order to minimize the systematic (average) phase error
for PBO, a PBO Phase Offset can be programmed in
0.101 ns steps in the cnfg_phase_offset_pbo register,
Reg.72. The range of the programmable PBO phase offset
is restricted to ±1.4 ns. This can be used to eliminate an
accumulation of phase shifts in one direction.
Input to Output Phase Adjustment
When PBO is off, such that the system always tries to align
the outputs to the inputs at the 0° position, there is a
mechanism provided in the ACS8520 for precise fine
tuning of the output phase position with respect to the
input. This can be used to compensate for circuit and
board wiring delays. The output phase can be adjusted in
6 ps steps up to 200 ns in a positive or negative direction.
The phase adjustment actually changes the phase
position of the feedback clock so that the DPLL adjusts
the output clock phases to compensate. The rate of
change of phase is therefore related to the DPLL
bandwidth. For the DPLL to track large instant changes in
phase, either Lock8k mode should be on, or the coarse
phase detector should be enabled. Register
cnfg_phase_offset at Reg. 70 and 71 controls the output
phase, which is only used when Phase Build-out is off
(Reg. 48, Bit 2 = 0 and Reg. 76, Bit 4 =0).
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
Input Wander and Jitter Tolerance
The ACS8520 is compliant to the requirements of all
relevant standards, principally ITU Recommendation
G.825[15], ANSI DS1.101-1999[1], Telcordia GR1244,
GR253, G812, G813 and ETS 300 462-5 (1997).
All reference clock inputs have a tight frequency tolerance
but a generous jitter tolerance. Pull-in, hold-in and pull-out
ranges are specified in Table 8. Minimum jitter tolerance
masks are specified in Figures 9 and 10, and Tables 8
and 10, respectively. The ACS8520 will tolerate wander
and jitter components greater than those shown in
Figure 9 and Figure 10, up to a limit determined by a
combination of the apparent long-term frequency offset
caused by wander and the eye-closure caused by jitter
(the input source will be rejected if the offset pushes the
frequency outside the hold-in range for long enough to be
detected, whilst the signal will also be rejected if the eye
closes sufficiently to affect the signal purity). Either the
Lock8k mode, or one of the extended phase capture
ranges should be engaged for high jitter tolerance
according to these masks.
All reference clock ports are monitored for quality,
including frequency offset and general activity. Single
short-term interruptions in selected reference clocks may
not cause re- arrangements, whilst longer interruptions,
or multiple, short-term interruptions, will cause rearrangements, as will frequency offsets which are
sufficiently large or sufficiently long to cause loss-of-lock
in the phase-locked loop. The failed reference source will
be removed from the priority table and declared as
unserviceable, until its perceived quality has been
restored to an acceptable level.
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DATASHEET
Table 8 Input Reference Source Jitter Tolerance
Jitter Tolerance
G.703[6]
Frequency
Monitor
Acceptance
Range
Frequency Acceptance Range
(Pull-in)
±16.6 ppm
±4.6 ppm (see Note (i))
±9.2 ppm (see Note (ii))
G.783[9]
Frequency Acceptance Range
(Hold-in)
Frequency Acceptance Range
(Pull-out)
±4.6 ppm (see Note (i))
±9.2 ppm (see Note (ii))
±4.6 ppm (see Note (i))
±9.2 ppm (see Note (ii))
G.823[13]
GR-1244-CORE[19]
Notes: (i) The frequency acceptance and generation range will be ±4.6 ppm around the required frequency when the external crystal
frequency accuracy is within a tolerance of ±4.6 ppm.
(ii) The fundamental acceptance range and generation range is ±9.2 ppm with an exact external crystal frequency of 12.800 MHz. This
is the default DPLL range, the range is also programmable from 0 to 80 ppm in 0.08 ppm steps.
Figure 9 Minimum Input Jitter Tolerance (OC-3/STM-1)
A0
A1
A2
A3
A4
Jitter and Wander Frequency (log scale)
f0
f1
f2
f3
f4
f5
f6
f7
f8
f9
F8530_003MINIPJITTOLOC3STM1_02
Note...For inputs supporting G.783[9] compliant sources.)
Table 9 Amplitude and Frequency Values for Jitter Tolerance (OC-3/STM-1)
STM
level
Peak to peak amplitude (unit
Interval)
A0
STM-1
2800
A1
A2
A3
A4
311 39 1.5 0.15
Revision 3.02/October 2005 © Semtech Corp.
Frequency (Hz)
F0
F1
F2
F3
F4
12 u 178 u 1.6 m 15.6 m 0.125
Page 27
F5
19.3
F6
F7
F8
F9
500 6.5 k 65 k 1.3
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Figure 10 Minimum Input Jitter Tolerance (DS1/E1)
Peak-to-peak Jitter and Wander Amplitude
(log scale)
A1
A2
Jitter and Wander Frequency (log scale)
f1
f2
f3
F8530D_004MINIPJITTOLDS1E1_02
f4
Table 10 Amplitude and Frequency Values for Jitter Tolerance (DS1/E1)
Type
Spec.
Amplitude (UI p-p)
A1
Frequency (Hz)
A2
F1
F2
F3
F4
DS1
GR-1244-CORE[19]
5
0.1
10
500
8k
40 k
E1
ITU G.823[13]
1.5
0.2
20
2.4 k
18 k
100
Using the DPLLs for Accurate Frequency and Phase
Reporting
The frequency monitors in the ACS8520 perform
frequency monitoring with a programmable acceptable
limit of up to ±60.96 ppm. The resolution of the
measurement is 3.8 ppm and the measured frequency
can be read back from Reg. 4C, with channel selection at
Reg. 4B. For more accurate measurement of both
frequency and phase, the T0 and T4 DPLLs and their
phase detectors, can be used to monitor both input
frequency and phase. The T0 DPLL is always monitoring
the currently locked to source, but if the T4 path is not
used then the T4 DPLL can be used as a roving phase and
frequency meter. Via software control it could be switched
to monitor each input in turn and both the phase and
frequency can be reported with a very fine resolution.
The registers sts_current_dpll_frequency (Reg. 0C,
Reg. 0D and Reg. 07) report the frequency of either the
T0 or T4 DPLL with respect to the external crystal XO
frequency (after calibration via Reg. 3C, 3D if used). The
selection of T4 or T0 DPLL reporting is made via Reg. 4B,
Bit 4. The value is a 19-bit signed number with one LSB
representing 0.0003068 ppm (range of ±80 ppm). This
value is actually the integral path value in the DPLL, and
as such corresponds to an averaged measurement of the
Revision 3.02/October 2005 © Semtech Corp.
input frequency, with an averaging time inversely
proportional to the DPLL bandwidth setting. Reading this
regularly can show how the currently locked source is
varying in value e.g. due to frequency wander on its input.
The input phase, as seen at the DPLL phase detector, can
be read back from register sts_current_phase, Reg. 77
and 78. T0 or T4 DPLL phase detector reporting is again
controlled by Reg. 4B, Bit 4. One LSB corresponds to
approximately 0.7 degrees phase difference. For the T0
DPLL this will be reporting the phase difference between
the input and the internal feedback clock. The phase
result is internally averaged or filtered with a -3 dB
attenuation point at approximately 100 Hz. For low DPLL
bandwidths, 0.1 Hz for example, this measured phase
information from the T0 DPLL gives input phase wander in
the frequency band from for example 0.1 Hz to 100 Hz.
This could be used to give a crude input MTIE
measurement up to an observation period of
approximately 1000 seconds using external software.
In addition, the T4 DPLL phase detector can be used to
make a phase measurement between two inputs.
Reg. 65, Bit 7 is used to switch one input to the T4 phase
detector over to the current T0 input. The other phase
detector input remains connected to the selected T4 input
source, the selected source can be forced via Reg. 35,
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Bits [3:0], or changed via the T4 priority (Reg. 18 to 1E,
when Reg. 4B, Bit 4 = 1).
Consequently the phase detector from the T4 DPLL could
be used to measure the phase difference between the
currently selected source and the stand-by source, or it
could be used to measure the phase wander of all standby sources with respect to the current source by selecting
each input in sequence. An MTIE and TDEV calculation
could be made for each input via external processing.
Configuration for Redundancy Protection
When two ACS8520 devices are to be used in a
redundancy-protection scheme within a Network Element
(NE), one will be designated as Master, one as Slave.
Table 11 How to Align Outputs of Two ACS8520
Devices
Action
Result
If possible, one device (the
nominated Slave) should lock to
the other device (the nominated
Master).
With the Slave locked to the
Master, their output frequencies
will be guaranteed to be the
same.
All programmed priorities within
the two devices should be the
same, except for the fact that
(1)the Master output is
designated the highest priority
input on the Slave.(2) the Slave
output is designated zero priority
(disabled) on the Master.
(Reg. 18 to 1E)
These two actions ensure that if
the Master device fails, the Slave
device will switch to lock to the
same source that the Master was
locked to before it failed.
It is expected that an NE will use the T0 output for its
internal operations. The phase of the outputs from the T4
path (TO8 & TO9) will not be aligned, unless the T4
outputs are locked to the T0 outputs.
In many applications, the clocks supplied into the system
are required to be aligned not only in frequency, but also
in phase between the Master and Slave devices. This
ensures minimal disturbance when any clock sink
switches between Master and Slave.
In order to ensure that the outputs of the two ACS8520s
are always aligned in frequency and phase, the
procedures in Table 11 should be followed.
In order to maintain the conditions outlined in Table 11 it
is necessary for software systems to maintain monitoring
and control functions. These monitoring functions should
either poll the device or respond to interrupts in order to
maintain the correct settings within the two devices.
Please refer to the descriptions or registers mentioned in
Table 11 and also Regs 34, 3B, 48, 67 and 69, for more
details on these associated settings. See also Application
Note AN-SETS-7.
Table 12 MSTSLVB Pin Operation
MSTSLVB
1=
Master
Any input detected as invalid in
one device should be disabled
within the other device.
(Reg. 0E/0F & 30/31)
Phase Build-out should be
disabled on the Slave whilst it is
locked to the Master.
This will ensure that the phase of
the Slave is locked to the phase
of the Master. It also enables the
use of the Phase offset control
register to compensate for delays
between the Master and Slave.
Revertive mode should be
enabled.
This will ensure that the Slave
locks to the Master although it
may have been locked to another
source previously.
The bandwidth of the Slave
should be set higher than that of
the Master (it is recommended to
configure the slave with the
highest supported bandwidth).
This ensures that any transient
occurring on the output of the
Master is followed as closely as
possible on the Slave.
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DATASHEET
Page 29
Feature
Setting
Reason
Priority of
input I11
As programmed
(program 0 to
ensure it gets
disabled)
Make sure that the
designated Master
device cannot lock to
the output of the
Slave device.
Phase
Build-out
As programmed in
register.
If the system
requires PBO, then
this being enabled
on the Master will
give the overall
system performance
with PBO. The slave
only needs to track
the Master (no PBO).
Revertive
mode
As programmed in
register.
Revertive behavior of
the Master in a
Master/Slave
system will define
the overall Revertive
behavior of the
system.
T0 DPLL
bandwidth
As programmed in
register (automatic
or manual).
Device selects
locked or acquisition
bandwidth.
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Table 12 MSTSLVB Pin Operation (cont...)
MSTSLVB
0=
Slave
Feature
Setting
Reason
Priority of
input I11
1 (highest priority).
When a Slave, this
input is designated
as that connected to
the output of the
Master.
Phase
Build-out
Disabled.
This ensures that the
Slave locks to the
Master with the
minimum phase
offset possible.
Revertive
mode
Enabled
This ensures that the
Slave always locks to
the Master when it is
available.
T0 DPLL
bandwidth
Forced to the
acquisition
bandwidth setting.
A higher bandwidth
on the Slave ensures
closer phase
tracking.
For direct hardware control of Master or Slave operation
the Master/Slave control pin (MSTSLVB) can be used to
externally control some of these functions according to
Table 12. These functions can also be controlled via
software.
Whilst the Master and Slave outputs could be crossconnected and connected to any input on the alternative
device, input I11 has been chosen as the input controlled
by the MSTSLVB pin.
Alignment of Priority Tables in Master and Slave
ACS8520
In a redundant system where the Slave is normally locked
to the Master device, if the Master device fails the Slave
device must revert to locking to the same external
reference that the Master was locked to. This will ensure
that minimum disturbance, both in frequency and phase,
is created on the output of the Slave device due to the
failure of the Master device. As stated previously
(Table 11), it is recommended that the programmed
priorities of the reference sources are the same in both
devices, apart from the Master/Slave cross-connect
inputs.
Both devices can also monitor all their reference sources
and determine the validity of each source. It is
recommended that the availability of valid sources are
also aligned between the two devices. This is achieved by
writing the value, as reported by sts_sources_valid
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
Reg. 0E & 0F), from one device into the
cnfg_sts_remote_sources_valid register (Reg. 30 & 31)
of the other. This will ensure that any source considered
invalid by one device is also considered invalid by the
other. If a failure of the Master does occur, this will ensure
that the Slave will always select the reference that the
Master was locked to.
T4 Generation in Master and Slave ACS8520
As specified by the I.T.U., there is no need to align the
phases of the T4 outputs in Master and Slave devices. For
a fully redundant system, there is a need, however, to
ensure that all devices select the same reference source.
As there is no need to guarantee the alignment of phase
of the T4 outputs, the Slave devices T4 input does not
need to lock to the Masters T4 output, but only needs to
ensure that it locks to the same external reference
source. The actions of aligning the priority tables and
available reference sources performed for the T0 outputs
will be equally valid for the T4 outputs. The only difference
being that the input connected to the Master's output is
disabled for the T4 path (allowing it only to lock to external
references). This can be easily achieved as the T4 and T0
paths have separate programmed priorities. There is no
defined Holdover requirement for the T4 path.
Alignment of the Output Clock Phases in Master
and Slave ACS8520
When the ACS8520 is locked to a reference source of
frequency f, the output clocks of frequency f will be inphase with the reference source (with Phase Build-out
disabled). As all T0 output clocks from the ACS8520 are
derived from the same T0 frequency, any frequency
greater than f at the output will be “falling edge aligned”
with the output at frequency f. Any frequency less than f
will be effectively a division of f, if possible. Similarly for
T4, all T4 output clocks will be phase-related to the T4
input.
The effect of this relationship is that if the Master and
Slave devices are cross-connected with 19.44 MHz
clocks, their output clocks at 19.44 MHz, 38.88 MHz,
77.76 MHz, 155.52 MHz & 311.04 MHz will be aligned
between the 2 devices. However, their outputs of
6.48 MHZ, 1.544 MHz, 2.048 MHz, 2 kHz and 8 kHz etc.
would not necessarily be aligned. Whilst most
applications would not be affected by the non-alignment
of most of these clocks, the non-alignment of the 2 kHz
and/or the 8 kHz may cause framing errors.
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There are 2 ways to align the 2 kHz and/or 8 kHz outputs:
1. the use of the External syncing function, or
2. directly locking the Slave to 2 kHz or 8 kHz from the
Master.
By directly locking the Slave to the 2 kHz (MFrSync) output
of the Master, all frequencies output from the Slave will
be in phase alignment with the same frequency
generated from the Master. If the Slave is directly locked
to the 8 kHz (FrSync) output from the Master, then all
frequencies except for 2 kHz MFrSync outputs will be in
alignment.
If using the external syncing function then two signals
need to be interconnected between the Master and Slave:
1. the clock and,
2. the Sync signal.
This requires some configuration enhancements. The
Sync signal is not locked to, it is sampled using the
reference clock and used to realign the generated
outputs. The generated outputs are still always locked to
the reference clock and related to each other. Details on
the Master and Slave interconnection wiring and software
configuration can be found in refer to the application note
AN-SETS-2. The following section describes the
resynchronization operation of the MFrSync via the
SYNC2K input.
MFrSync and FrSync Alignment-SYNC2K
The SYNC2K input (pin 45) is monitored by the ACS8520
for consistent phase and correct frequency and if it does
not pass these quality checks, an alarm flag is raised
(Reg. 08, Bit 7 and Reg. 09, Bit 7). The check for
consistent phase involves checking that each input edge
is within an expected timing window. The window size is
set by Reg. 7C, Bits [6:4]. An internal detector senses that
a correct SYNC2K signal is present and only then allows
the signal to resynchronize the internal dividers that
generate the 8 kHz FrSync and 2 kHz MFrSync outputs.
This sequence avoids spurious resynchronizations that
may otherwise occur with connections and
disconnections of the SYNC2K input.
The SYNC2K input will normally be a 2 kHz frequency, only
its falling edge is used. It can however be at a frequencies
of 4 kHz or 8 kHz without any change to the register
setups. Only alignment of the 8 kHz will be achieved in
this case.
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
Safe sampling of the SYNC2K input is achieved by using
the currently selected clock reference source to do the
input sampling. This is based on the principle that FrSync
alignment is being used on a Slave device that is locked
to the clock reference of a Master device that is also
providing the 2 kHz SYNC2K input. Phase Build-out mode
should be off (Reg. 48, Bit 2 = 0). The 2 kHz MFrSync
output from the Master device has its falling edge aligned
with the falling edge of the other output clocks, hence the
SYNC2K input is normally sampled on the rising edge of
the current input reference clock, in order to provide the
most margin. Some modification of the expected timing of
the SYNC2K with respect to the reference clock can be
achieved via Reg. 7B, Bits [1:0]. This allows for the
SYNC2K input to arrive either half a reference clock cycle
early or up to one and a half cycle late, hence allowing a
safe sampling margin to be maintained.
A different sampling resolution is used depending on the
input reference frequency and the setting of Reg. 7B Bit 6,
cnfg_sync_phase. With this bit Low, the SYNC2K input
sampling has a 6.48 MHz resolution, this being the
preferred reference frequency to lock to from the Master,
in conjunction with the SYNC2K 2 kHz, since it gives the
most timing margin on the sampling and aligns all of the
higher rate OC-3 derived clocks. When Bit 6 is high the
SYNC2K can have a sampling resolution of either
19.44 MHz (when the current locked to reference is
19.44 MHz) or 38.88 MHz (all other frequencies). This
would allow for instance a 19.44 MHz and 2 kHz pair to
be used for Slave synchronization or for Line card
synchronization. Reg. 7B Bit 7, indep_FrSync/MFrSync
controls whether the 2 kHz MFrSync and 8 kHz FrSync
outputs keep their precise alignment with the other
output clocks.
When indep_FrSync/MFrSync Reg. 7B Bit 7 is Low the
FrSyncs and the other higher rate clocks are not
independent and their alignment on the falling 8kHz edge
is maintained. This means that when Bit Sync_OC-N_rates
is High, the OC-N rate dividers and clocks are also
synchronized by the SYNC2K input. On a change of phase
position of the SYNC2K, this could result in a shift in
phase of the 6.48 MHz output clock when a 19.44 MHz
precision is used for the SYNC2K input. To avoid
disturbing any of the output clocks and only align the
MFrSync and FrSync outputs, at the chosen level of
precision, then independent Frame Sync mode can be
used (Reg. 7B, Bit 7 = 1). Edge alignment of the FrSync
output with other clocks outputs may then change
depending on the SYNC2K sampling precision used. For
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example, with a 19.44 MHz reference input clock and
Reg. 7B, Bits 6 and 7 both High (independent mode and
Sync OC-N rates), then the FrSync output will still align
with the 19.44 MHz output but not with the 6.48 MHz
output clock.
The FrSync and MFrSync outputs always come from the
T0 DPLL path. 2kHz and 8kHz outputs can also be
produced at the TO1 to TO7 outputs. These can come
from either the T0 DPLL or from the T4 DPLL, controlled
by Reg. 7A, Bit 7.
If required, this allows the T4 DPLL to be used as a
separate PLL for the FrSync and MFrSync path with a
2 kHz input and 2 kHz and 8 kHz Frame Sync outputs.
Output Clock Ports
The device supports a set of main output clocks, T0 and
T4, and a pair of secondary Sync outputs, FrSync and
MFrSync. The two main output clocks, T0 and T4, are
independent of each other and are individually selectable.
The two secondary output clocks, FrSync and MFrSync,
are derived from either T0 or T4. The frequencies of the
main output clocks are selectable from a range of predefined spot frequencies and a variety of output
technologies are supported, as defined in Table 13.
PECL/LVDS/AMI Output Port Selection
The choice of PECL or LVDS compatibility is programmed
via the cnfg_differential_outputs register, Reg. 3A.
AMI port, TO8, supports a composite clock, consisting of a
64 kHz AMI clock with 8 kHz boundaries marked by
deliberate violations of the AMI coding rules, as specified
in ITU recommendation G.703[6]. Departures from the
nominal pattern are detected within the ACS8520, and
may cause reference-switching if too frequent. See “DC
Characteristics: AMI Input/Output Port” on page 138., for
more details.
Output Frequency Selection and Configuration
The output frequency at many of the outputs is controlled
by a number of inter-dependent parameters. These
parameters control the selections within the various
blocks shown in Figure 11.
The ACS8520 contains two main DPLL/APLL paths. Whilst
they are largely independent, there are a number of ways
in which these two structures can interact. Figure 11
shows an expansion of the original Block Diagram
(Figure 1) for the PLL paths.
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
T0 DPLL and APLLs
The T0 DPLL always produces 77.76 MHz regardless of
either the reference frequency (frequency at the input pin
of the device) or the locking frequency (frequency at the
input of the DPLL Phase and Frequency Detector (PFD)).
The input reference is either passed directly to the PFD or
via a pre-divider (not shown) to produce the reference
input. The feedback 77.76 MHz is either divided or
synthesized to generate the locking frequency.
Digital Frequency Synthesis (DFS) is a technique for
generating an output frequency using a higher frequency
system clock (204.8 MHz in the case of the 77.76 MHz
synthesis). However, the edges of the output clock are not
ideally placed in time, since all edges of the output clock
will be aligned to the active edge of the system clock. This
will mean that the generated clock will inherently have
jitter on it equivalent to one period of the system clock.
The T0 77M forward DFS block uses DFS clocked by the
204.8 MHz system clock to synthesize the 77.76 MHz
and, therefore, has an inherent 4.9 ns of p-p jitter. There
is an option to use an APLL, the T0 feedback APLL, to filter
out this jitter before the 77.76 MHz is used to generate
the feedback locking frequency in the T0 feedback DFS
block. This analog feedback option allows a lower jitter
(<1 ns) feedback signal to give maximum performance.
The digital feedback option is present so that when the
output path is switched to digital feedback the two paths
remain synchronized.
The T0 77M forward DFS block is also the block that
handles Phase Build-out and any phase offset
programmed into the device. Hence, the T0 77M forward
DFS and the T0 77M output DFS blocks are locked in
frequency but may be offset in phase.
The T0 77M output DFS block also uses the 204.8 MHz
system clock and always generates 77.76 MHz for the
output clocks (with inherent 4.9 ns of jitter). This is fed to
another DFS block and to the T0 output APLL. The low
frequency T0 LF output DFS block is used to produce
three frequencies; two of them, Digital1 and Digital2, are
available for selection to be produced at outputs TO1TO7, and the third frequency can produce multiple
E1/DS1 rates via the filtering APLLs. The input clock to
the T0 LF output DFS block is either 77.76 MHz from the
T0 output APLL (post jitter filtering) or 77.76 MHz direct
from the T0 77M output DFS. Utilizing the clock from the
T0 output APLL will result in lower jitter outputs from the
T0 LF output DFS block.
Page 32
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Figure 11 PLL Block Diagram
T4
Reference
Input
Lock_T4_to_T0
Sts_Current_Phase
Control
T4_DPLL_Frequency
T4_APLL_for_T0
0
Forward
DFS
PFD and
Loop Filter
0
T4_Dig_Feedback
T0_DPLL_Freq
1
1
1
T4
Output
Dividers
T4
Output
APLL
TO1 to TO7
0
T4 DPLL
Locking
Frequency
Feedback
DFS
T4_Op_From_TO
0
0
1
TO8 /TO9
8 kHz
T0_DPLL_Frequency
Control
0
77M
Output
DFS
Sts_Current_Phase
T0
Reference
Input
PFD and
Loop Filter
PBO
Phase
Offset
1
LF
Output
DFS
0
1
T0
Output
APLL
T0
Output
Dividers
TO1 to TO7
TO1 to TO7
TO10/TO11
T0_DPLL_Frequency
Control
77M
Forward
DFS
1
T0
Feedback
APLL
1
Locking
Frequency
Feedback
DFS
0
T0 DPLL
Analog
F8530D_017BLOCKDIA_04
However, when the input to the T0 APLL is taken from the
T0 LF output DFS block, the input to that block comes
directly from the T0 77M output DFS block so that a “loop”
is not created.
in the table. Similar to the T0 path, the output of the T4
forward DFS block is generated using DFS clocked by the
204.8 MHz system clock and will have an inherent jitter of
4.9 ns.
The T0 output APLL is for multiplying and filtering. The
input to the T0 output APLL can be either 77.76 MHz from
the T0 77M output DFS block or an alternative frequency
from the T0 LF output DFS block (offering 77.76 MHz,
12E1, 16E1, 24DS1 or 16DS1). The frequency from the
T0 output APLL is four times its input frequency i.e.
311.04 MHz when used with a 77.76 MHz input. The T0
output APLL is subsequently divided by 1, 2, 4, 6, 8, 12,
16 and 48 and these are available at the TO1-TO7
outputs.
The T4 feedback DFS also has the facility to be able to use
the post T4 APLL (jitter-filtered) clock to generate the
feedback locking frequency. Again, this will give the
maximum performance by using a low jitter feedback.
(a) Output from the T4 forward DFS block (12E1, 24DS1,
16E1, 16DS1, E3, DS3, OC-N),
T4 DPLL & APLL
The T4 path is much simpler than the T0 path. This path
offers no Phase Build-out or phase offset. The T4 input
can be used to either lock to a reference clock input
independent of the T0 path, or lock to the T0 path. Unlike
the T0 path, the T4 forward DFS block does not always
generate 77.76 MHz. The possible frequencies are listed
Revision 3.02/October 2005 © Semtech Corp.
The T4 output APLL block is also for multiplying and
filtering. The input to the T4 output APLL can come either
from the T4 forward DFS block or from the T0 path. The
input to the T4 output APLL can be programmed to be one
of the following:
(b) 12E1 from T0,
(c) 16E1 from T0,
(d) 24DS1 from T0,
(e) 16DS1 from T0.
Page 33
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The frequency generated from the T4 output APLL block is
four times its input frequency i.e. 311.04 MHz when used
with a 77.76 MHz input. The T4 output APLL is
subsequently divided by 2, 4, 8, 12, 16, 48 and 64 and
these are available at the TO1-TO7 outputs.
The TO8 and TO9 outputs are driven from either the T4 or
the T0 path. The TO10 and TO11 outputs are always
generated from the T0 path. Reg.7A Bit 7 selects whether
the source of the 2 kHz and 8 kHz outputs available from
TO1-TO7 is derived from either the T0 or the T4 paths.
Output Frequency Configuration Steps
The output frequency selection is performed in the
following steps:
1. Does the application require the use of the T4 path as
an independent PLL path or not. If not, then the T4
DATASHEET
path can be utilized to produce extra frequencies
locked to the T0 path.
2. Refer to Table 15, Frequency Divider Look-up, to
choose a set of output frequencies- one for each path,
T4 and T0. Only one set of frequencies can be
generated simultaneously from each path.
3. Refer to the Table 15 to determine the required APLL
frequency to support the frequency set.
4. Refer to Table 16, T0 APLL Frequencies, and
Table 17, T4 APLL Frequencies, to determine what
mode the T0 and T4 paths need to be configured in,
considering the output jitter level.
5. Refer to Table 18, TO1 - TO7 output Frequency
Selection, and the column headings in Table 15,
Frequency Divider Look-up, to select the appropriate
frequency from either of the APLLs on each output as
required.
Table 13 Output Reference Source Selection Table
Port
Name
Output Port
Technology
Frequencies Supported
T01
TTL/CMOS
T02
TTL/CMOS
T03
TTL/CMOS
T04
TTL/CMOS
T05
TTL/CMOS
T06
LVDS/PECL
(LVDS default)
T07
PECL/LVDS
(PECL default)
T08
AMI
64/8 kHz (composite clock, 64 kHz + 8 kHz), fixed frequency.
T09
TTL/CMOS
Fixed frequency, either 1.544 MHz or 2.048 MHz.
T010
TTL/CMOS
FrSync, 8 kHz programmable pulse width and polarity, see Reg. 7A.
T011
TTL/CMOS
MFrSync, 2 kHz programmable pulse width and polarity, see Reg. 7A.
Frequency selection as per Table 14 and Table 18
Note...1.544 MHz/2.048 MHz are shown for SONET/SDH respectively. Pin SONSDHB controls default, when High SONET is default.
Revision 3.02/October 2005 © Semtech Corp.
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Table 14 Output Frequency Selection
Frequency (MHz, unless stated otherwise)
T0 DPLL Mode
T4 DPLL Mode
T4 APLL Input Mux
Jitter Level (typ)
rms
(ps)
p-p
(ns)
2 kHz
77.76 MHz Analog
-
-
60
0.6
2 kHz
Any digital feedback mode
-
-
1400
5
8 kHz
77.76 MHz Analog
-
-
60
0.6
8 kHz
Any digital feedback mode
-
-
1400
5
Select T4 DPLL
500
2.3
Select T0 DPLL 12E1
250
1.5
Select T4 DPLL
200
1.2
-
Select T0 DPLL 16DS1
150
1.0
1.536
(not TO4/TO5)
-
1.536
(not TO4/TO5)
-
1.544
(not TO4/TO5)
-
1.544
(not TO4/TO5)
-
1.544
via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
1.544
via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
Select T4 DPLL
500
2.3
Select T0 DPLL 12E1
250
1.5
Select T4 DPLL
400
2.0
Select T0 DPLL 16E1
220
1.2
2.048
-
2.048
-
2.048
(not TO4/TO5)
-
2.048
(not TO4/TO5)
-
2.048
(not TO6)
2.048
2.048
12E1 mode
12E1 mode
16DS1 mode
12E1 mode
16E1 mode
-
-
900
4.5
via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
Select T4 DPLL
200
1.2
2.059
-
2.059
-
-
Select T0 DPLL 16DS1
150
1.0
16DS1 mode
-
-
760
2.6
Select T4 DPLL
110
0.75
Select T0 DPLL 24DS1
110
0.75
Select T4 DPLL
400
1.5
Select T0 DPLL 16E1
220
1.2
250
1.6
2.059
(not TO6)
2.316
(not TO4/TO5)
-
2.316
(not TO4/TO5)
-
2.731
-
2.731
-
2.731
(not TO6)
2.796
(not TO4/TO5)
16E1 mode
16DS1 mode
24DS1 mode
16E1 mode
-
-
-
DS3 mode
Select T4 DPLL
110
1.0
3.088
-
24DS1 mode
Select T4 DPLL
110
0.75
3.088
-
-
Select T0 DPLL 24DS1
110
0.75
24DS1 mode
-
-
110
0.75
3.088
(not TO6)
3.088
via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
3.088
via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
Revision 3.02/October 2005 © Semtech Corp.
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Table 14 Output Frequency Selection (cont...)
Frequency (MHz, unless stated otherwise)
T0 DPLL Mode
3.728
-
T4 DPLL Mode
DS3 mode
T4 APLL Input Mux
Jitter Level (typ)
Select T4 DPLL
rms
(ps)
p-p
(ns)
110
1.0
4.096
via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
4.096
via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
4.296
(not TO4/TO5)
-
E3 mode
120
1.0
4.86
(not TO4/TO5)
-
77.76 MHz mode Select T4 DPLL
60
0.6
-
E3 mode
120
1.0
900
4.5
Select T4 DPLL
500
2.3
Select T0 DPLL 12E1
250
1.5
760
2.6
Select T4 DPLL
200
1.2
-
Select T0 DPLL 16DS1
150
1.0
5.728
6.144
12E1 mode
-
6.144
-
12E1 mode
6.144
-
-
6.176
16DS1 mode
-
6.176
-
6.176
-
16DS1 mode
Select T4 DPLL
Select T4 DPLL
-
-
6.176
via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
6.176
via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
60
0.6
6.48
-
77.76 MHz mode Select T4 DPLL
6.48
(not TO6)
77.76 MHz analog
-
-
60
0.6
6.48
(not TO6)
77.76 MHz digital
-
-
60
0.6
8.192
12E1 mode
-
-
900
4.5
8.192
16E1 mode
-
-
250
1.6
Select T4 DPLL
400
2.0
Select T0 DPLL 16E1
220
1.2
8.192
-
8.192
-
16E1 mode
-
8.192
via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
8.192
via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
8.235
16DS1 mode
-
-
760
2.6
9.264
24DS1 mode
-
-
110
0.75
9.264
-
Select T4 DPLL
110
0.75
9.264
-
-
Select T0 DPLL 24DS1
110
0.75
-
-
250
1.6
110
1.0
900
4.5
500
2.3
10.923
16E1 mode
11.184
12.288
12.288
Revision 3.02/October 2005 © Semtech Corp.
12E1 mode
24DS1 mode
DS3 mode
-
-
Page 36
12E1 mode
Select T4 DPLL
Select T4 DPLL
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Table 14 Output Frequency Selection (cont...)
Frequency (MHz, unless stated otherwise)
T0 DPLL Mode
T4 DPLL Mode
T4 APLL Input Mux
Jitter Level (typ)
p-p
(ns)
250
1.5
12.288
-
-
12.352
24DS1 mode
-
-
110
0.75
12.352
16DS1 mode
-
-
760
2.6
12.352
-
Select T4 DPLL
200
1.2
12.352
-
-
Select T0 DPLL 16DS1
150
1.0
12.352 via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
12.352 via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
16.384
12E1 mode
-
-
900
4.5
16.384
16E1 mode
-
-
250
1.6
Select T4 DPLL
400
2.0
Select T0 DPLL 16E1
220
1.2
16.384
-
16.384
-
16DS1 mode
16E1 mode
-
Select T0 DPLL 12E1
rms
(ps)
16.384 via Digital1 (not TO7) or Digital2 (not TO6) 77.76 MHz Analog
-
-
3800
13
16.384 via Digital1 (not TO7) or Digital2 (not TO6) Any digital feedback mode
-
-
3800
18
16.469
16DS1 mode
-
-
760
2.6
17.184
-
E3 mode
120
1.0
18.528
24DS1 mode
-
110
0.75
18.528
-
Select T4 DPLL
110
0.75
18.528
-
-
Select T0 DPLL 24DS1
110
0.75
24DS1 mode
Select T4 DPLL
-
19.44
77.76 MHz analog
-
-
60
0.6
19.44
77.76 MHz digital
-
-
60
0.6
60
0.6
250
1.6
110
1.0
900
4.5
Select T4 DPLL
500
2.3
Select T0 DPLL 12E1
250
1.5
19.44
21.845
16E1 mode
22.368
24.576
77.76MHz mode Select T4 DPLL
-
12E1 mode
DS3 mode
-
Select T4 DPLL
-
24.576
-
24.576
-
-
24.704
24DS1 mode
-
-
110
0.75
24.704
16DS1 mode
-
-
760
2.6
24.704
-
Select T4 DPLL
200
1.2
24.704
-
-
Select T0 DPLL 16DS1
150
1.0
-
-
60
0.6
25.92
Revision 3.02/October 2005 © Semtech Corp.
77.76 MHz analog
Page 37
12E1 mode
-
16DS1 mode
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Table 14 Output Frequency Selection (cont...)
Frequency (MHz, unless stated otherwise)
T0 DPLL Mode
T4 DPLL Mode
T4 APLL Input Mux
Jitter Level (typ)
rms
(ps)
p-p
(ns)
25.92
77.76 MHz digital
-
-
60
0.6
32.768
16E1 mode
-
-
250
1.6
Select T4 DPLL
400
2.0
Select T0 DPLL 16E1
220
1.2
Select T4 DPLL
120
1.0
110
0.75
Select T4 DPLL
110
0.75
-
Select T0 DPLL 24DS1
110
0.75
32.768
-
16E1 mode
32.768
-
-
34.368
-
E3 mode
37.056
24DS1 mode
-
37.056
-
37.056
-
24DS1 mode
-
38.88
77.76 MHz analog
-
-
60
0.6
38.88
77.76 MHz digital
-
-
60
0.6
38.88
-
77.76 MHz mode Select T4 DPLL
60
0.6
44.736
-
DS3 mode
Select T4 DPLL
110
1.0
49.152 (TO4/TO5 only)
-
12E1 mode
Select T4 DPLL
500
2.3
49.152 (TO4/TO5 only)
-
Select T0 DPLL 12E1
250
1.5
900
4.5
Select T4 DPLL
200
1.2
49.152 (TO6/TO7 only)
12E1 mode
-
49.408 (TO4/TO5 only)
-
49.408 (TO4/TO5 only)
-
-
Select T0 DPLL 16DS1
150
1.0
49.408 (TO6/TO7 only)
16DS1 mode
-
-
760
2.6
51.84
77.76 MHz analog
-
-
60
0.6
51.84
77.76 MHz digital
-
-
60
0.6
Select T4 DPLL
400
2.0
Select T0 DPLL 16E1
220
1.2
250
1.6
65.536 (TO4/TO5 only)
-
65.536 (TO4/TO5 only)
-
65.536 (TO6/TO7 only)
16E1 mode
16DS1 mode
-
16E1 mode
-
-
68.736
-
E3 mode
Select T4 DPLL
120
1.0
74.112 (TO4/TO5 only)
-
24DS1 mode
Select T4 DPLL
110
0.75
74.112 (TO4/TO5 only)
-
-
Select T0 DPLL 24DS1
110
0.75
74.112 (TO6/TO7 only)
24DS1 mode
-
-
110
0.75
77.76
77.76 MHz analog
-
-
60
0.6
77.76
77.76 MHz digital
-
-
60
0.6
77.76
-
77.76 MHz mode Select T4 DPLL
60
0.6
89.472 (TO4/TO5 only)
-
DS3 mode
110
1.0
Revision 3.02/October 2005 © Semtech Corp.
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Select T4 DPLL
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Table 14 Output Frequency Selection (cont...)
Frequency (MHz, unless stated otherwise)
T0 DPLL Mode
T4 DPLL Mode
T4 APLL Input Mux
Jitter Level (typ)
rms
(ps)
p-p
(ns)
98.304 (TO6 only)
12E1 mode
-
-
900
4.5
98.816 (TO6 only)
16DS1 mode
-
-
760
2.6
131.07 (TO6 only)
16E1 mode
-
-
250
1.6
120
1.0
110
0.75
60
0.6
137.47 (TO4/TO5 only)
148.22 (TO6 only)
-
E3 mode
24DS1 mode
-
155.52 (TO4/TO5 only)
-
Select T4 DPLL
-
77.76 MHz mode Select T4 DPLL
155.52 (TO6/TO7 only)
77.76 MHz analog
-
-
60
0.6
155.52 (TO6/TO7 only)
77.76 MHz digital
-
-
60
0.6
311.04 (TO6 only)
77.76 MHz analog
-
-
60
0.6
311.04 (TO6 only)
77.76 MHz digital
-
-
60
0.6
Table 15 Frequency Divider Look-up
APLL
Frequency
APLL/2
APLL/4
APLL/6
51.84
APLL/8
311.04
155.52
77.76
38.88
274.944
137.472
68.376
-
34.368
178.944
89.472
44.736
-
148.224
74.112
37.056
131.072
65.536
98.816
98.304
APLL/12
25.92
APLL/16
APLL/48
APLL/64
19.44
6.48
4.86
-
17.184
5.728
4.296
22.368
-
11.184
3.728
2.796
24,704
18.528
12.352
9.264
3.088
2.316
32.768
21.84533
16.384
10.92267
8.192
2.730667
2.048
49.408
24.704
16.46933
12.352
8.234667
6.176
2.058667
1.544
49.152
24.576
16.384
12.288
8.192
6.144
2.048
1.536
Note...All frequencies in MHz
Revision 3.02/October 2005 © Semtech Corp.
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DATASHEET
Table 16 T0 APLL Frequencies
T0 APLL Frequency
T0 Mode
T0 DPLL Frequency Control Register Bits
Reg. 65 Bits[2:0]
Output Jitter Level
ns (p-p)
311.04
Normal (digital feedback)
000
<0.5
311.04 MHz
Normal (analog feedback)
001
<0.5
98.304 MHz
12E1 (digital feedback)
010
<2
131.072 MHz
16E1 (digital feedback)
011
<2
148.224 MHz
24DS1 (digital feedback)
100
<2
98.816 MHz
16DS1 (digital feedback)
101
<2
-
Do not use
110
-
-
Do not use
111
-
Table 17 T4 APLL Frequencies
T4 APLL
Frequency
T4 Mode
T4 Forward DFS
Frequency
(MHz)
T4 DPLL Frequency
Control Register Bits
Reg. 64 Bits [2:0]
T4 APLL for T0
Enable Register Bit
Reg. 65 Bit 6
T0 Frequency to T4
APLL Register Bits
Reg. 65 Bits [5:4]
Output Jitter Level
ns (p-p)
311.04 MHz
Squelched
77.76
000
0
XX
<0.5
311.04 MHz
Normal
77.76
001
0
XX
<0.5
98.304 MHz
12E1
24.576
010
0
XX
<0.5
131.072 MHz
16E1
32.768
011
0
XX
<0.5
148.224 MHz
24DS1
37.056
(2*18.528)
100
0
XX
<0.5
98.816 MHz
16DS1
24.704
101
0
XX
<0.5
274.944 MHz
E3
68.736
(2*34.368)
110
0
XX
<0.5
178.944 MHz
DS3
44.736
111
0
XX
<0.5
98.304 MHz
T0-12E1
-
XXX
1
00
<2
131.072 MHz
T0-16E1
-
XXX
1
01
<2
148.224 MHz
T0-24DS1
-
XXX
1
10
<2
98.816 MHz
T0-16DS1
-
XXX
1
11
<2
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Table 18 TO1 - TO7 Output Frequency Selection
Output Frequency for given “Value in Register” for each Output Port’s Cnfg_output_frequency Register
Value in Register
TO1, Reg. 60
Bits [3:0]
TO2, Reg. 60
Bits [7:4]
TO3, Reg. 61
Bits [3:0]
TO4, Reg. 61
Bits [7:4]
TO5, Reg. 62
Bits [3:0]
TO6, Reg. 62
Bits [7:4]
TO7, Reg. 63
Bits [3:0]
0000
Off
Off
Off
Off
Off
Off
Off
0001
2 kHz
2 kHz
2 kHz
2 kHz
2 kHz
2 kHz
2 kHz
0010
8 kHz
8 kHz
8 kHz
8 kHz
8 kHz
8 kHz
8 kHz
0011
Digital2
Digital2
Digital2
Digital2
Digital2
T0 APLL/2
Digital2
0100
Digital1
Digital1
Digital1
Digital1
Digital1
Digital1
T0 APLL/2
0101
T0 APLL/48
T0 APLL/48
T0 APLL/48
T0 APLL/48
T0 APLL/48
T0 APLL/1
T0 APLL/48
0110
T0 APLL/16
T0 APLL/16
T0 APLL/16
T0 APLL/16
T0 APLL/16
T0 APLL/16
T0 APLL/16
0111
T0 APLL/12
T0 APLL/12
T0 APLL/12
T0 APLL/12
T0 APLL/12
T0 APLL/12
T0 APLL/12
1000
T0 APLL/8
T0 APLL/8
T0 APLL/8
T0 APLL/8
T0 APLL/8
T0 APLL/8
T0 APLL/8
1001
T0 APLL/6
T0 APLL/6
T0 APLL/6
T0 APLL/6
T0 APLL/6
T0 APLL/6
T0 APLL/6
1010
T0 APLL/4
T0 APLL/4
T0 APLL/4
T0 APLL/4
T0 APLL/4
T0 APLL/4
T0 APLL/4
1011
T4 APLL/64
T4 APLL/64
T4 APLL/64
T4 APLL/2
T4 APLL/2
T4 APLL/64
T4 APLL/64
1100
T4 APLL/48
T4 APLL/48
T4 APLL/48
T4 APLL/48
T4 APLL/48
T4 APLL/48
T4 APLL/48
1101
T4 APLL/16
T4 APLL/16
T4 APLL/16
T4 APLL/16
T4 APLL/16
T4 APLL/16
T4 APLL/16
1110
T4 APLL/8
T4 APLL/8
T4 APLL/8
T4 APLL/8
T4 APLL/8
T4 APLL/8
T4 APLL/8
1111
T4 APLL/4
T4 APLL/4
T4 APLL/4
T4 APLL/4
T4 APLL/4
T4 APLL/4
T4 APLL/4
T4 Low Frequency Outputs
TO8 is an AMI composite clock output. If enabled, this
always produces a 64 kHz/8 kHz composite clock. If
enabled, TO9 always produces an E1 or DS1 frequency
output. Both TO8 and TO9 are generated by DFS within
either the T0 or T4 path, as controlled by Reg. 35 Bit 4.
The frequencies generated from TO8 and TO9 are
independent of the Mode (frequency) of either the T4 or
the T0 paths. The amount of jitter generated on the TO8
and TO9 outputs will be related to the clock period of the
source DFS block added to any jitter present on that clock.
This is detailed in the following text.
As can be seen in the block diagram, the DFS blocks used
to generate these outputs are the T4 feedback DFS block
in the case of the T4 path and the T0 LF output DFS block
for the T0 path. The T4 feedback DFS block is clocked by
the T4 forward DFS, or its APLL. The frequency of the T4
forward DFS block can be determined by referring to
Table 17 (T4 APLL frequencies). This is in the region of
65 MHz to89 MHz and can be approximated to have a
Revision 3.02/October 2005 © Semtech Corp.
period of between 11 ns and 15 ns. The output of the T4
forward DFS block will have an inherent p-p jitter of
approximately 4.9 ns. The clock to the T4 feedback DFS
block will have <1 ns of jitter when the T4 path is in analog
feedback mode (Reg. 35 Bit 6 = 0). However, it will have
4.9 ns when in digital feedback mode.
The TO8 output, being 64 kHz/8 kHz, can be directly
divided from the clock to the T4 feedback DFS block;
therefore, it will have a similar amount of jitter on it, i.e.
<1 ns when using analog feedback, and 4.9 ns when
using digital feedback.
The TO9 output will have more jitter because it is
synthesized from the clock to the T4 feedback DFS block.
The jitter, in addition to that present on the clock to the T4
feedback DFS block, will be equivalent to a period of that
clock, i.e. between 11 ns and 15 ns. The jitter present on
the TO9 output will range from 11 ns (when the T4 path is
in DS3 mode - 89 MHz combined with analog feedback) to
20 ns (when in 16E1 mode - 65 MHz combined with
digital feedback).
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ACS8520 SETS
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FINAL
The T4 outputs TO8 and TO9 can be enabled/disabled via
Reg. 63 Bits [5:4].
DATASHEET
clock). The maximum jitter is generated when in digital
feedback mode, when the total is approximately 17 ns.
TO10, TO11, 2 kHz and 8 kHz Clock Outputs
“Digital” Frequencies
It can be seen from Table 18 (TO1-TO7 output frequency
selection) that frequencies listed as Digital1 and Digital2
can be selected. Digital1 is a single frequency selected
from the range shown in Table 19. Digital2 is another
single frequency selected from the same range. The T0 LF
output DFS block shown in the diagram and clocked
either by the T0 77M output DFS block or via the T0
output APLL, generates these two frequencies. The input
clock frequency of the DFS is always 77.76 MHz and as
such has a period of approximately 12 ns. The jitter
generated on the Digital outputs is relatively high, due to
the fact that they do not pass through an APLL for jitter
filtering. The minimum level of jitter is when the T0 path is
in analog feedback mode, when the p-p jitter will be
approximately 12 ns (equivalent to a period of the DFS
It can be seen from Table 18 (TO1 - TO7 Output Frequency
Selection) that frequencies listed as 2 kHz and 8 kHz can
be selected. Whilst the TO10 and TO11 outputs are
always supplied from the T0 path, the 2 kHz and 8 kHz
options available from the TO1 - TO7 outputs are all
supplied from either the T0 or T4 path (Reg. 7A Bit 7).
The outputs can be either clocks (50:50 mark-space) or
pulses and can be inverted. When pulses are configured
on the output, the pulse width will be one cycle of the
output of TO3 (TO3 must be configured to generate at
least 1544 kHz to ensure that pulses are generated
correctly). Figure 12 shows the various options with the
8 kHz controls in Reg. 7A. There is an identical
arrangement with Reg. 7A Bits [1:0] and the 2 kHz/TO11
outputs. Outputs TO10 and TO11 can be disabled via
Reg. 63 Bits [7:6].
Figure 12 Control of 8k Options.
T03 output
T03 output
T010/8kHz output
T010/8kHz output
a) Clock non-inverted, Reg.7A[3:2] = 00
c) Clock inverted, Reg.7A[3:2] = 10
T03 output
T03 output
T010/8kHz output
T010/8kHz output
b) Pulse non-inverted, Reg.7A[3:2] = 01
d) Pulse inverted, Reg.7A[3:2] = 11
Table 19 Digital Frequency Selections
Digital1 Control
Reg.39 Bits [5:4]
Digital1 SONET/
SDH Reg. 38 Bit5
Digital1 Frequency
(MHz)
Digital2 Control
Reg. 39 Bits[7:6]
Digital2 SONET/SDH
Reg.38 Bit6
Digital2 Frequency
(MHz)
00
0
2.048
00
0
2.048
01
0
4.096
01
0
4.096
10
0
8.192
10
0
8.192
11
0
16.384
11
0
16.384
00
1
1.544
00
1
1.544
01
1
3.088
01
1
3.088
10
1
6.176
10
1
6.176
11
1
12.352
11
1
12.352
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Microprocessor Interface
FINAL
DATASHEET
Introduction to Microprocessor Modes
The ACS8520 incorporates a microprocessor interface, which can be configured for all common microprocessor
interface types, via the bus interface mode control pins UPSEL(2:0) as defined in Table 20.
These pins are read at power up and set the interface mode.
The optional EPROM mode allows the internal registers to be loaded from the EPROM when the device comes out of
“Power-On Reset” mode. The microprocessor interface type can be altered after power up by Reg. 7F, such that for
instance the device could boot up in EPROM mode and then switch to Motorola mode, for example, after the EPROM
data has preconditioned the device. Reading of Data from the EPROM at boot up time is handled automatically by the
ACS8520. The chip select of the EPROM should be driven from the micro in the case of mixed EPROM and micro
communication, in order to avoid conflict between EPROM and ACS8520 access from the microprocessor.
The following sections show the interface timings for each interface type.
Table 20 Microprocessor Interface Mode Selection
UPSEL(2:0)
Mode
Description
111 (7)
OFF
Interface disabled
110 (6)
OFF
Interface disabled
101 (5)
SERIAL
Serial uP bus interface
100 (4)
MOTOROLA
Motorola interface
011 (3)
INTEL
Intel compatible bus interface
010 (2)
MULTIPLEXED
Multiplexed bus interface
001 (1)
EPROM
EPROM read mode
000 (0)
OFF
Interface disabled
Timing diagrams for the different microprocessor modes are presented on pages 44 to 52.
Revision 3.02/October 2005 © Semtech Corp.
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DATASHEET
Motorola Mode
In MOTOROLA mode, the device is configured to interface with a microprocessor using a 680x0 type bus as parallel
data + address. Figure 13 and Figure 14 show the timing diagrams of read and write accesses for this mode.
Figure 13 Read Access Timing in MOTOROLA Mode
tpw1
CSB
tsu2
WRB
th2
X
X
th1
tsu1
A
X
address
X
td1
AD
Z
data
td2
RDY
(DTACK)
td3
tpw2
th3
Z
td4
Z
Z
F8110D_007ReadAccMotor_01
Table 21 Read Access Timing in MOTOROLA Mode (for use with Figure 13)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup A valid to CSBfalling edge
4 ns
-
-
tsu2
Setup WRB valid to CSBfalling edge
0 ns
-
-
td1
Delay CSBfalling edge to AD valid (consecutive Read - Read)
12 ns
-
40 ns
Delay CSBfalling edge to AD valid (consecutive Write - Read)
16 ns
-
192 ns
td2
Delay CSBfalling edge to DTACKrising edge
-
-
13 ns
td3
Delay CSBrising edge to AD high-Z
-
-
10 ns
td4
Delay CSBrising edge to RDY high-Z
-
-
9 ns
tpw1
CSB Low time (consecutive Read - Read)
25 ns
62 ns
-
CSB Low time (consecutive Write - Read)
25 ns
193 ns
-
RDY High time (consecutive Read - Read)
12 ns
-
49 ns
RDY High time (consecutive Write - Read)
12 ns
-
182 ns
th1
Hold A valid after CSBrising edge
0 ns
-
-
th2
Hold WRB valid after CSBrising edge
0 ns
-
-
th3
Hold CSB Low after RDYfalling edge
0 ns
-
-
tp
Time between (consecutive Read - Read) accesses (CSBrising edge to
CSBfalling edge)
15 ns
-
-
tp
Time between (consecutive Write - Read) accesses (CSBrising edge to
CSBfalling edge)
160 ns
-
-
tpw2
Revision 3.02/October 2005 © Semtech Corp.
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ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Figure 14 Write Access Timing in MOTOROLA Mode
tpw1
CSB
tsu2
WRB
th2
X
X
th1
tsu1
A
X
address
X
tsu3
AD
data
X
td2
RDY
(DTACK)
th4
tpw2
th3
X
td4
Z
Z
F8110D_008WriteAccMotor_01
Table 22 Write Access Timing in MOTOROLA Mode (for use with Figure 14)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup A valid to CSBfalling edge
4 ns
-
-
tsu2
Setup WRB valid to CSBfalling edge
0 ns
-
-
tsu3
Setup AD valid before CSBrising edge
8 ns
-
-
td2
Delay CSBfalling edge to RDYrising edge
-
-
13 ns
td4
Delay CSBrising edge to RDY High-Z
-
-
7 ns
tpw1
CSB Low time
25 ns
-
180 ns
tpw2
RDY High time
12 ns
-
166 ns
th1
Hold A valid after CSBrising edge
8 ns
-
-
th2
Hold WRB Low after CSBrising edge
0 ns
-
-
th3
Hold CSB Low after RDYfalling edge
0 ns
-
-
th4
Hold AD valid after CSBrising edge
9 ns
-
-
tp
Time between consecutive accesses (CSBrising edge to CSBfalling edge)
160 ns
-
-
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Intel Mode
In Intel mode, the device is configured to interface with a microprocessor using a 80x86 type bus as parallel data +
address. Figure 15 and Figure 16 show the timing diagrams of read and write accesses for this mode.
Figure 15 Read Access Timing in INTEL Mode
CSB
WRB
tpw1
tsu2
th2
RDB
th1
tsu1
A
address
td4
td1
Z
data
AD
td3
td2
tpw2
th3
td5
Z
RDY
F8110D_009ReadAccIntel_01
Table 23 Read Access Timing in INTEL Mode (for use with Figure 15)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup A valid to CSBfalling edge
4 ns
-
-
tsu2
Setup CSBfalling edge to RDBfalling edge
0 ns
-
-
td1
Delay RDBfalling edge to AD valid (consecutive Read - Read)
12 ns
-
40 ns
Delay RDBfalling edge to AD valid (consecutive Write - Read)
12 ns
-
193 ns
td2
Delay CSBfalling edge to RDY active
-
-
13 ns
td3
Delay RDBfalling edge to RDYfalling edge
-
-
14 ns
td4
Delay RDBrising edge to AD high-Z
-
-
10 ns
td5
Delay CSBrising edge to RDY high-Z
-
-
11 ns
tpw1
RDB Low time (consecutive Read - Read)
35 ns
60 ns
-
RDB Low time (consecutive Write - Read)
35 ns
195 ns
-
RDY Low time (consecutive Read - Read)
20 ns
-
45 ns
RDY Low time (consecutive Write - Read)
20 ns
-
182 ns
th1
Hold A valid after RDBrising edge
0 ns
-
-
th2
Hold CSB Low after RDBrising edge
0 ns
-
-
th3
Hold RDB Low after RDYrising edge
0 ns
-
-
tp
Time between (consecutive Read - Read) accesses (RDBrising edge to
RDBfalling edge, or RDBrising edge to WRBfalling edge)
15 ns
-
-
tp
Time between (consecutive Write - Read) accesses (RDBrising edge to
RDBfalling edge, or RDBrising edge to WRBfalling edge)
160 ns
-
-
tpw2
Revision 3.02/October 2005 © Semtech Corp.
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FINAL
DATASHEET
Figure 16 Write Access Timing in INTEL Mode
CSB
tpw1
tsu2
th2
WRB
RDB
tsu1
th1
address
A
tsu3
th4
data
AD
td3
td2
RDY
tpw2
th3
td5
Z
Z
F8110D_010WriteAccIntel_01
Table 24 Write Access Timing in INTEL Mode (for use with Figure 16)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup A valid to CSBfalling edge
4 ns
-
-
tsu2
Setup CSBfalling edge to WRBfalling edge
0 ns
-
-
tsu3
Setup AD valid before WRBrising edge
6 ns
-
-
td2
Delay CSBfalling edge to RDY active
-
-
13 ns
td3
Delay WRBfalling edge to RDYfalling edge
-
-
14 ns
td5
Delay CSBrising edge to RDY high-Z
-
-
10 ns
tpw1
WRB Low time
25 ns
185 ns
-
tpw2
RDY Low time
10 ns
-
173 ns
th1
Hold A valid after WRBrising edge
12 ns
-
-
th2
Hold CSB Low after WRBrising edge
0 ns
-
-
th3
Hold WRB Low after RDYrising edge
0 ns
-
-
th4
Hold AD valid after WRBrising edge
4 ns
-
-
tp
Time between consecutive accesses (WRBrising edge to WRBfalling edge,
or WRBrising edge to RDBfalling edge)
160 ns
-
-
Revision 3.02/October 2005 © Semtech Corp.
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DATASHEET
Multiplexed Mode
In Multiplexed Mode, the device is configured to interface with microprocessors (e.g., Intel's 80x86 family) which share
bus signals between address and data. Figures 17 and 18 show the timing diagrams of read and write accesses.
Figure 17 Read Access Timing in MULTIPLEXED Mode
tpw3
tp1
ALE
tsu1
th1
CSB
tsu2
WRB
tpw1
th2
RDB
td1
address
AD
X
td2
RDY
td4
data
td3
tpw2
X
th3
td5
Z
Z
F8110D_011ReadAccMultiplex_01
Table 25 Read Access Timing in MULTIPLEXED Mode (for use with Figure 17)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup AD address valid to ALEfalling edge
5 ns
-
-
tsu2
Setup CSBfalling edge to RDBfalling edge
0 ns
-
-
td1
Delay RDBfalling edge to AD data valid (consecutive Read - Read)
12 ns
-
40 ns
Delay RDBfalling edge to AD data valid (consecutive Write - Read)
17 ns
-
193 ns
td2
Delay CSBfalling edge to RDY active
-
-
13 ns
td3
Delay RDBfalling edge to RDYfalling edge
-
-
15 ns
td4
Delay RDBrising edge to AD data high-Z
-
-
10 ns
td5
Delay CSBrising edge to RDY high-Z
-
-
10 ns
tpw1
RDB Low time (consecutive Read - Read)
35 ns
60 ns
-
RDB Low time (consecutive Write - Read)
35 ns
200 ns
-
RDY Low time (consecutive Read - Read)
20 ns
-
40 ns
RDY Low time (consecutive Write - Read)
20 ns
-
185 ns
tpw3
ALE High time
5 ns
-
-
th1
Hold AD address valid after ALEfalling edge
9 ns
-
-
th2
Hold CSB Low after RDBrising edge
0 ns
-
-
th3
Hold RDB Low after RDYrising edge
0 ns
-
-
tp1
Time between ALEfalling edge and RDBfalling edge
0 ns
-
-
tp2
Time between (consecutive Read - Read) accesses (RDBrising edge to
ALErising edge)
20 ns
-
-
tp2
Time between (consecutive Write - Read) accesses (RDBrising edge to
ALErising edge)
160 ns
-
-
tpw2
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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DATASHEET
Figure 18 Write Access Timing in MULTIPLEXED Mode
tpw3
tp1
ALE
tsu1
th1
CSB
tsu2
th2
tpw1
WRB
RDB
tsu3
address
AD
X
td2
RDY
th4
data
td3
tpw2
X
th3
td5
Z
Z
F8110D_012WriteAccMultiplex_01
Table 26 Write Access Timing in MULTIPLEXED Mode (For use with Figure 18)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Set up AD address valid to ALEfalling edge
5 ns
-
-
tsu2
Set up CSBfalling edge to WRBfalling edge
0 ns
-
-
tsu3
Set up AD data valid to WRBrising edge
5 ns
-
-
td2
Delay CSBfalling edge to RDY active
-
-
13 ns
td3
Delay WRBfalling edge to RDYfalling edge
-
-
15 ns
td5
Delay CSBrising edge to RDY high-Z
-
-
9 ns
tpw1
WRB Low time
30 ns
188 ns
-
tpw2
RDY Low time
15 ns
-
173 ns
tpw3
ALE High time
5 ns
-
-
th1
Hold AD address valid after ALEfalling edge
9 ns
-
-
th2
Hold CSB Low after WRBrising edge
0 ns
-
-
th3
Hold WRB Low after RDYrising edge
0 ns
-
-
th4
AD data hold valid after WRBrising edge
7 ns
-
-
tp1
Time between ALEfalling edge and WRBfalling edge
0 ns
-
-
tp2
Time between consecutive accesses (WRBrising edge to ALErising edge)
1600 ns
-
-
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
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DATASHEET
Serial Mode
In SERIAL Mode, the device is configured to interface with a serial microprocessor bus. Figure 19 and Figure 20 show
the timing diagrams of read and write accesses for this mode. The serial interface can be SPI compatible.
The Motorola SPI convention is such that address and data is transmitted and received MSB first. On the ACS8520,
device address and data are transmitted and received LSB first. Address, read/write control and data on the SDI pin
is latched into the device on the rising edge of the SCLK. During a read operation, serial data output on the SDO pin
can be read out of the device on either the rising or falling edge of the SCLK depending on the logic level of CLKE (note
CLKE=A(1)). For standard Motorola SPI compliance, data should be clocked out of the SDO pin on the rising edge of
the SCLK so that it may be latched into the microprocessor on the falling edge of the SCLK.
The serial interface clock (SCLK) is not required to run between accesses (i.e., when CSB = 1).
Figure 19 Read Access Timing in SERIAL Mode
A(1) = CLKE = 0; SDO data is clocked out on the rising edge of SCLK
CSB
tsu2
tpw2
th2
ALE=SCLK
th1
tsu1
_
A(0) = SDI
R/W
tpw1
A0 A1 A2 A3 A4 A5 A6
td1
AD(0)=SDO
Output not driven, pulled low by internal resistor
td2
D0 D1 D2 D3 D4 D5 D6 D7
A(1) = CLKE = 1; SDO data is clocked out on the falling edge of SCLK
CSB
th2
ALE=SCLK
_
A(0)=SDI
R/W
A0 A1 A2 A3 A4 A5 A6
td1
AD(0)=SDO
Output not driven, pulled low by internal resistor
td2
D0 D1 D2 D3 D4 D5 D6 D7
F8530D_013ReadAccSerial_02
Table 27 Read Access Timing in SERIAL Mode (For use with Figure 19)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup SDI valid to SCLKrising edge
4 ns
-
-
tsu2
Setup CSBfalling edge to SCLKrising edge
14 ns
-
-
td1
Delay SCLKrising edge (SCLKfalling edge for CLKE = 1) to SDO valid
-
-
18 ns
td2
Delay CSBrising edge to SDO high-Z
-
-
16 ns
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Table 27 Read Access Timing in SERIAL Mode (For use with Figure 19) (cont...)
Symbol
Parameter
MIN
TYP
MAX
tpw1
SCLK Low time
22 ns
-
-
tpw2
SCLK High time
22 ns
-
-
th1
Hold SDI valid after SCLKrising edge
6 ns
-
-
th2
Hold CSB Low after SCLKrising edge, for CLKE = 0
Hold CSB Low after SCLKfalling edge, for CLKE = 1
5 ns
-
-
tp
Time between consecutive accesses (CSBrising edge to CSBfalling edge)
10 ns
-
-
Figure 20 Write Access Timing in SERIAL Mode
CSB
tsu2
tpw2
th2
ALE=SCLK
th1
tsu1
_
A(0)=SDI
AD(0)=SDO
R/W
tpw1
A0 A1 A2 A3 A4 A5 A6 D0 D1 D2 D3 D4 D5 D6 D7
Output not driven, pulled low by internal resistor
F8110D_014WriteAccSerial_02
Table 28 Write Access Timing in SERIAL Mode (For use with Figure 20)
Symbol
Parameter
MIN
TYP
MAX
tsu1
Setup SDI valid to SCLKrising edge
4 ns
-
-
tsu2
Setup CSBfalling edge to SCLKrising edge
14 ns
-
-
tpw1
SCLK Low time
22 ns
-
-
tpw2
SCLK High time
22 ns
-
-
th1
Hold SDI valid after SCLKrising edge
6 ns
-
-
th2
Hold CSB Low after SCLKrising edge
5 ns
-
-
tp
Time between consecutive accesses (CSBrising edge to CSBfalling edge)
10 ns
-
-
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
EPROM Mode
This mode is suitable for use with an EPROM, in which configuration data is stored (one-way communication - status
information will not be accessible). A state machine internal to the ACS8520 device will perform numerous EPROM
read operations to read the data out of the EPROM. In EPROM Mode, the ACS8520 takes control of the bus as Master
and reads the device set-up from an AMD AM27C64 type EPROM at lowest speed (250ns) after device set-up (system
reset). The EPROM access state machine in the up interface sequences the accesses. Figure 21 shows the access
timing of the device in EPROM mode.
Further information can be found in the AMD AM27C64 datasheet.
Figure 21 Access Timing in EPROM mode
CSB (=OEB)
address
A
tacc
Z
AD
Z
data
F8110D_015ReadAccEEPROM_01
Table 29 Access Timing in EPROM mode (For use with Figure 21)
Symbol
tacc
Parameter
Delay CSBfalling edge or A change to AD valid
MIN
TYP
MAX
-
-
920 ns
Power-On Reset
The Power-On Reset (PORB) pin resets the device if forced Low. The reset is asynchronous, the minimum Low pulse
width is 5 ns. Reset is needed to initialize all of the register values to their defaults. Reset must be asserted at power
on, and may be re-asserted at any time to restore defaults. This is implemented simply using an external capacitor to
GND along with the internal pull-up resistor. The ACS8520 is held in a reset state for 250 ms after the PORB pin has
been pulled High. In normal operation PORB should be held High.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Register Map
FINAL
cleared by writing a 1 into each bit of the field (writing a 0
value into a bit will not affect the value of the bit).
Each Register, or register group, is described in the
following Register Map (Table 30) and subsequent
Register Description Tables.
Configuration Registers
Register Organization
The ACS8520 SETS uses a total of 118 8-bit register
locations, identified by a Register Name and
corresponding hexadecimal Register Address. They are
presented here in ascending order of Reg. address. and
each Register is organized with the most-significant bit
positioned in the left-most bit, and bit significance
decreasing towards the right-most bit. Some registers
carry several individual data fields of various sizes, from
single-bit values (e.g. flags) upwards. Several data fields
are spread across multiple registers, as shown in the
Register Map, Table 30. Shaded areas in the map are
“don’t care” and writing either 0 or 1 will not affect any
function of the device. Bits labelled “Set to zero” or “Set
to one” must be set as stated during initialization of the
device, either following power- up, or after a Power-On
Reset (POR). Failure to correctly set these bits may result
in the device operating in an unexpected way.
CAUTION! Do not write to any undefined register
addresses as this may cause the device to operate in a
test mode. If an undefined register has been
inadvertently addressed, the device should be reset to
ensure the undefined registers are at default values.
Multi-word Registers
For Multi-word Registers (e.g. Reg. 0C and 0D), all the
words have to be written to their separate addresses, and
without any other access taking place, before their
combined value can take effect. If the sequence is
interrupted, the sequence of writes will be ignored.
Reading a multi-word address freezes the other address
words of a multi-word address so that the bytes all
correspond to the same complete word.
Register Access
Most registers are of one of two types, configuration
registers or status registers, the exceptions being the
chip_id and chip_revision registers. Configuration
registers may be written to or read from at any time (the
complete 8-bit register must be written, even if only one
bit is being modified). All status registers may be read at
any time and, in some status registers (such as the
sts_interrupts register), any individual data field may be
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
Each configuration register reverts to a default value on
power-up or following a reset. Most default values are
fixed, but some will be pin-settable. All configuration
registers can be read out over the microprocessor port.
Status Registers
The Status Registers contain readable registers. They may
all be read from outside the chip but are not writeable
from outside the chip (except for a clearing operation). All
status registers are read via shadow registers to avoid
data hits due to dynamic operation. Each individual status
register has a unique location.
Interrupt Enable and Clear
Interrupt requests are flagged on pin INTREQ; the active
state (High or Low) is programmable and the pin can
either be driven, or set to high impedance when nonactive (Reg 7D refers).
Bits in the interrupt status register are set (High) by:
1.
2.
3.
4.
Any reference source becoming valid or going invalid.
Change in the operating state (e.g. Locked, Holdover)
A brief loss of the currently selected reference source.
An AMI input error.
All interrupt sources, see Reg. 05, Reg. 06 and Reg. 08,
are maskable via the mask register, each one being
enabled by writing a 1 to the appropriate bit. Any
unmasked bit set in the interrupt status register will cause
the interrupt request pin to be asserted. All interrupts are
cleared by writing a 1 to the bit(s) to be cleared in the
status register. When all pending unmasked interrupts
are cleared the interrupt pin will go inactive.
Defaults
Each Register is given a defined default value at reset and
these are listed in the Map and Description Tables.
However, some read-only status registers may not
necessarily show the same default values after reset as
those given in the tables. This is because they reflect the
status of the device which may have changed in the time
it takes to carry out the read, or through reasons of
configuration. In the same way, the default values given
for shaded areas could also take different values to those
stated.
Page 53
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Table 30 Register Map
Data Bit
Address
(hex)
Default
(hex)
Register Name
RO = Read Only
R/W = Read/Write
7 (MSB)
6
chip_id (RO)
00
chip_revision (RO)
test_register1 (R/W)
03
14
phase_alarm
disable_180
sts_interrupts (R/W)
05
FF
I8 valid
change
I7 valid
change
06
3F
operating_
mode
main_ref_
failed
sts_current_DPLL_frequency, see
OC/OD
07
00
sts_interrupts (R/W)
08
50
Sync_ip_alarm T4_status
sts_operating (RO)
09
41
SYNC2K_
alarm
sts_priority_table (RO)
5
4
3
2
1
48
Device part number [7:0] 8 least significant bits of the chip ID
01
21
Device part number [15:8] 8 most significant bits of the chip ID
02
00
0 (LSB)
Chip revision number [7:0]
resync_
analog
Set to 0
8K edge
polarity
Set to zero
Set to zero
I6 valid
change
I5 valid
change
I4 valid
change
I3 valid
change
I2 valid
change
I1 valid
change
I14 valid
change
I13 valid
change
I12 valid
change
I11 valid
change
I10 valid
change
I9 valid
change
Bits [18:16] of current DPLL frequency
T4_DPLL_lock
T4_inputs_
failed
TO_DPLL_freq
_soft_alarm
AMI2_Viol
AMI2_LOS
T4_DPLL_freq
_soft_alarm
AMI1_Viol
T0_DPLL_operating_mode
0A
00
Highest priority validated source
Currently selected source
0B
00
3rd highest priority validated source
2nd highest priority validated source
sts_current_DPLL_frequency [7:0] 0C
00
Bits [7:0] of current DPLL frequency
[15:8] 0D 00
Bits [15:8] of current DPLL frequency
(RO)
[18:16] 07
00
0E
00
0F
00
sts_sources_valid (RO)
sts_reference_sources (RO)
Status of inputs:
Bits [18:16] of current DPLL frequency
I8
I7
Out-of-band
alarm (soft)
Out-of-band
alarm (hard)
I6
I5
I4
I3
I2
I1
I14
I13
I12
I11
I10
I9
No activity
alarm
Phase lock
alarm
Out-of-band
alarm (soft)
Out-of band
alarm (hard)
No activity
alarm
Phase lock
alarm
Input pairs (1 & 2) 10
66
Status of I2 Input
Status of I1 Input
(3 & 4) 11
66
Status of I4 Input
Status of I3 Input
(5 & 6) 12
66
Status of I6 Input
Status of I5 Input
(7 & 8) 13
66
Status of I8 Input
Status of I7 Input
(9 & 10) 14
66
Status of I10 Input
Status of I9 Input
(11 & 12) 15
66
Status of I12 Input
Status of I11 Input
(13 & 14) 16
66
Status of I14 Input
Status of I13 Input
cnfg_ref_selection_priority (1 & 2) 18
32
programmed_priority I2
programmed_priority I1
(R/W)
(3 & 4) 19
54
programmed_priority I4
programmed_priority I3
(5 & 6) 1A
76
programmed_priority I6
programmed_priority I5
(7 & 8) 1B
98
programmed_priority I8
programmed_priority I7
(9 & 10) 1C
BA
programmed_priority I10
programmed_priority I9
(11 & 12) 1D DC
programmed_priority I12
programmed_priority I11
(13 & 14) 1E
programmed_priority I14
programmed_priority I13
FE
cnfg_ref_source_frequency_
_1 20
00
Set to zero
bucket_id_1
Set to zero
(R/W)
_2 21
00
Set to zero
bucket_id_2
Set to zero
3 22
00
divn_3
lock8k_3
bucket_id_3
reference_source_frequency_3
4 23
00
divn_4
lock8k_4
bucket_id_4
reference_source_frequency_4
5 24
03
divn_5
lock8k_5
bucket_id_5
reference_source_frequency_5
6 25
03
divn_6
lock8k_6
bucket_id_6
reference_source_frequency_6
7 26
03
divn_7
lock8k_7
bucket_id_7
reference_source_frequency_7
8 27
03
divn_8
lock8k_8
bucket_id_8
reference_source_frequency_8
9 28
03
divn_9
lock8k_9
bucket_id_9
reference_source_frequency_9
10 29
03
divn_10
lock8k_10
bucket_id_10
reference_source_frequency_10
11 2A
03
divn_11
lock8k_11
bucket_id_11
reference_source_frequency_11
12 2B
01
divn_12
lock8k_12
bucket_id_12
reference_source_frequency_12
13 2C
01
divn_13
lock8k_13
bucket_id_13
reference_source_frequency_13
14 2D 01
divn_14
lock8k_14
bucket_id_14
reference_source_frequency_14
cnfg_sts_remote_sources_valid
(R/W)
30
FF
31
3F
cnfg_operating_mode (R/W)
32
00
force_select_reference_source
(R/W)
33
0F
AMI1_LOS
Revision 3.02/October 2005 © Semtech Corp.
Remote status, channels <8:1>
Remote status, channels <14:9>
TO_DPLL_operating_mode
forced_reference_source
Page 54
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Table 30 Register Map (cont...)
Address
(hex)
Default
(hex)
Register Name
RO = Read Only
R/W = Read/Write
Data Bit
7 (MSB)
6
cnfg_input_mode
(Bit 1 RO, otherwise R/W)
34
C2
auto_extsync_
en
phalarm_
timeout
cnfg_T4_path (R/W)
35
40
lock_T4_to_T0
T4_dig_
feedback
cnfg_differential_inputs (R/W)
36
02
cnfg_uPsel_pins (RO)
37
02
cnfg_dig_outputs_sonsdh (R/W)
38
1F
cnfg_digtial_frequencies (R/W)
39
08
cnfg_differential_outputs (R/W)
3A
C6
cnfg_auto_bw_sel (R/W)
3B
FB
[7:0] 3C
99
cnfg_nominal_frequency
(R/W)
5
4
XO_ edge
man_holdover
(R/W)
2
I6_PECL
dig2_sonsdh
digital2_frequency
I5_LVDS
dig1_sonsdh
digital1_frequency
T07_PECL_LVDS
T06_LVDS_PECL
T0_lim_int
auto_BW_sel
Nominal frequency [7:0]
Nominal frequency [15:8]
00
Holdover frequency [7:0]
00
Holdover frequency [15:8]
88
reversion_
mode
Microprocessor type
[7:0] 3E
40
0 (LSB)
master_slaveb
T4_forced_reference_source
[15:8] 3F
cnfg_holdover_modes (R/W)
1
ip_sonsdhb
T4_op_
from_T0
[15:8] 3D 99
cnfg_holdover_frequency
3
extsync_en
auto_
averaging
fast_averaging read_average
mini_holdover_mode
Holdover frequency [18:16]
(with Registers 3E and 3F above)
cnfg_DPLL_freq_limit (R/W) [7:0] 41
76
[9:8] 42
00
cnfg_interrupt_mask (R/W) [7:0] 43
00
I8 interrupt not
masked
I7 interrupt not
masked
I6 interrupt not
masked
I5 interrupt not
masked
I4 interrupt not
masked
I3 interrupt not
masked
I2 interrupt not
masked
I1 interrupt not
masked
[15:8] 44
00
Operating_
mode interrupt
not masked
Main_ref_
failed interrupt
not masked
I14 interrupt
not masked
I13 interrupt
not masked
I12 interrupt
not masked
I11 interrupt
not masked
I10 interrupt
not masked
I9 interrupt not
masked
[23:16] 45
00
Sync_ip_
T4_status
alarm interrupt interrupt not
not masked
masked
T4_inputs_
failed interrupt
not masked
AMI2_Viol
interrupt not
masked
AMI2_LOS
interrupt not
masked
AMI1_Viol
interrupt not
masked
AMI1_LOS
interrupt not
masked
freq_monitor_
soft_enable
freq_monitor_
hard_enable
cnfg_freq_divn (R/W)
DPLL frequency offset limit [7:0]
DPLL frequency offset limit [9:8]
[7:0] 46
FF
[13:8] 47
3F
divn_value [7:0]
cnfg_monitors (R/W)
48
05
cnfg_freq_mon_threshold (R/W)
49
23
soft_frequency_alarm_threshold [3:0]
hard_frequency_alarm_threshold [3:0]
cnfg_current_freq_mon_
threshold (R/W)
4A
23
current_soft_frequency_alarm_threshold [3:0]
current_hard_frequency_alarm_threshold [3:0]
cnfg_registers_source_select
(R/W)
4B
00
sts_freq_measurement (R/W)
4C
00
cnfg_DPLL_soft_limit (R/W)
4D 8E
divn_value [13:8]
freq_mon_clk
los_flag_
on_ TDO
ultra_fast_
switch
ext_switch
T4_T0_select
PBO_freeze
PBO_en
frequency_measurement_channel_select [3:0]
freq_measurement_value [7:0]
Freq limit
Phase loss
enable
DPLL Frequency Soft Alarm Limit [6:0] Resolution = 0.628 ppm
cnfg_upper_threshold_0 (R/W)
50
06
Configuration 0: Activity alarm set threshold [7:0]
cnfg_lower_threshold_0 (R/W)
51
04
Configuration 0: Activity alarm reset threshold [7:0]
cnfg_bucket_size_0 (R/W)
52
08
Configuration 0: Activity alarm bucket size [7:0]
cnfg_decay_rate_0 (R/W)
53
01
cnfg_upper_threshold_1 (R/W)
54
06
Configuration 1: Activity alarm set threshold [7:0]
Cfg 0:decay_rate [1:0]
cnfg_lower_threshold_1 (R/W)
55
04
Configuration 1: Activity alarm reset threshold [7:0]
cnfg_bucket_size_1 (R/W)
56
08
Configuration 1: Activity alarm bucket size [7:0]
cnfg_decay_rate_1 (R/W)
57
01
cnfg_upper_threshold_2 (R/W)
58
06
Configuration 2: Activity alarm set threshold [7:0]
Cfg 1:decay_rate [1:0]
cnfg_lower_threshold_2 (R/W)
59
04
Configuration 2: Activity alarm reset threshold [7:0]
cnfg_bucket_size_2 (R/W)
5A
08
Configuration 2: Activity alarm bucket size [7:0]
cnfg_decay_rate_2 (R/W)
5B
01
cnfg_upper_threshold_3 (R/W)
5C
06
cnfg_lower_threshold_3 (R/W)
5D 04
cnfg_bucket_size_3 (R/W)
5E
08
cnfg_decay_rate_3 (R/W)
5F
01
Revision 3.02/October 2005 © Semtech Corp.
Cfg 2:decay_rate [1:0]
Configuration 3: Activity alarm set threshold [7:0]
Configuration 3: Activity alarm reset threshold [7:0]
Configuration 3: Activity alarm bucket size [7:0]
Cfg 3:decay_rate [1:0]
Page 55
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Table 30 Register Map (cont...)
Address
(hex)
Default
(hex)
Register Name
RO = Read Only
R/W = Read/Write
Data Bit
7 (MSB)
6
5
4
3
2
1
0 (LSB)
cnfg_output_frequency (R/W)
(TO1 & TO2) 60
85
output_freq_2 (TO2)
output_freq_1 (TO1)
(TO3 & TO4) 61
86
output_freq_4 (TO4)
output_freq_3 (TO3)
(TO5 & TO6) 62
8A
output_freq_6 (TO6)
(TO7 to TO11) 63
F6
cnfg_T4_DPLL_frequency (R/W)
64
01
cnfg_T0_DPLL_frequency (R/W)
65
01
cnfg_T4_DPLL_bw (R/W)
66
00
cnfg_T0_DPLL_locked_bw (R/W)
67
0B
MFrSync
enable
T4 for
measuring T0
phase
output_freq_5 (TO5)
FrSync enable
TO9 enable
TO8 enable
Auto Disable
T4 output
AMI Duty cycle
T4 SONET/
SDH selection
T4 APLL for T0
E1/DS1
output_freq_7 <TO7>
T4_DPLL_frequency
T0_DPLL_frequency
T0 Freq to T4 APLL
T4_DPLL_bandwidth [1:0]
T0_DPLL_locked_bandwidth [4:0]
T0_DPLL_acquisition_bandwidth [4:0]
cnfg_T0_DPLL_acq_bw (R/W)
69
0F
cnfg_T4_DPLL_damping (R/W)
6A
13
T4_PD2_gain_alog_8K [6:4]
cnfg_T0_DPLL_damping (R/W)
6B
13
T0_PD2_gain_alog_8K [6:4]
T0_damping [2:0]
cnfg_T4_DPLL_PD2_gain (R/W)
6C
C2
T4_PD2_gain_
enable
T4_PD2_gain_alog [6:4]
T4_PD2_gain_digital [2:0]
cnfg_T0_DPLL_PD2_gain (R/W)
6D C2
T0_PD2_gain_
enable
T0_PD2_gain_alog [6:4]
T0_PD2_gain_digital [2:0]
cnfg_phase_offset (R/W)
[7:0] 70
00
phase_offset_value[7:0]
[15:8] 71
00
phase_offset_value[15:8]
cnfg_PBO_phase_offset (R/W)
PBO_phase_offset [5:0]
72
00
cnfg_phase_loss_fine_limit (R/W) 73
A2
Fine limit
Phase loss
enable (1)
No activity for
phase loss
Test bit
Set to 1
cnfg_phase_loss_coarse_limit
(R/W)
74
85
Coarse limit
Phase loss
enable (2)
Wide range
enable
Enable Multi
Phase resp.
cnfg_phasemon (R/W)
76
06
Input noise
window enable
sts_current_phase (RO)
T4_damping [2:0]
phase_loss_fine_limit [2:0]
Phase loss coarse limit in UI p-p [3:0]
[7:0] 77
00
current_phase[7:0]
[15:8] 78
00
current_phase[15:8]
cnfg_phase_alarm_timeout
(R/W)
79
32
cnfg_sync_pulses (R/W)
7A
00
2 k/8 k out
from T4
cnfg_sync_phase (R/W)
7B
00
indep_FrSync/
MFrSync
cnfg_sync_monitor (R/W)
7C
2B
ph_offset_
ramp
cnfg_interrupt (R/W)
7D 02
cnfg_protection(R/W)
7E
85
cnfg_uPsel (R/W)
7F
02
*
Timeout value in 2s intervals [5:0]
Revision 3.02/October 2005 © Semtech Corp.
8 k invert
8 k pulse
enable
2 k invert
Sync_OC-N_
rates
2 k pulse
enable
Sync_phase
Sync_monitor_limit
Sync_reference_source
GPO interrupt
enable
Interrupt
tristate
enable
Interrupt
polarity
enable
protection_value
Microprocessor type (*Default value depends on
value on UPSEL[2:0] pins)
Page 56
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Register Descriptions
FINAL
DATASHEET
Address (hex): 00
Register Name
chip_id
Bit 7
Bit 6
Description
Bit 5
(RO) 8 least significant bits of the Default Value
chip ID.
Bit 4
Bit 3
Bit 2
Bit 1
0100 1000
Bit 0
chip_id[7:0]
Bit No.
[7:0]
Description
Bit Value
chip_id
Least significant byte of the 2-byte device ID
48 (hex)
Value Description
Address (hex): 01
Register Name
chip_id
Bit 7
Bit 6
Description
Bit 5
(RO) 8 most significant bits of the Default Value
chip ID.
Bit 4
Bit 3
Bit 2
Bit 1
0010 0001
Bit 0
chip_id[15:8]
Bit No.
[7:0]
Description
Bit Value
chip_id
Most significant byte of the 2-byte device ID
21 (hex)
Value Description
Address (hex): 02
Register Name
Bit 7
chip_revision
Bit 6
Description
Bit 5
(RO) Silicon revision of the device. Default Value
Bit 4
Bit 3
Bit 2
Bit 1
0000 0000
Bit 0
chip_revision[7:0]
Bit No.
[7:0]
Description
Bit Value
chip_revision
Silicon revision of the device
00 (hex)
Revision 3.02/October 2005 © Semtech Corp.
Page 57
Value Description
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 03
Register Name
Bit 7
phase_alarm
Bit No.
test_register1
Bit 6
FINAL
Description
Bit 5
disable_180
DATASHEET
(R/W) Register containing various Default Value
test controls (not normally used).
Bit 4
Bit 3
resync_analog
Set to zero
Description
Bit Value
Bit 2
0001 0100
Bit 1
Bit 0
8k Edge Polarity Set to zero
Set to zero
Value Description
7
phase_alarm (phase alarm (R/O))
Instantaneous result from T0 DPLL
0
1
T0 DPLL reporting phase locked.
T0 DPLL reporting phase lost.
6
disable_180
Normally the DPLL will try to lock to the nearest
edge (±180°) for the first 2 seconds when locking to
a new reference. If the DPLL does not determine
that it is phase locked after this time, then the
capture range reverts to ±360°, which corresponds
to frequency and phase locking. Forcing the DPLL
into frequency locking mode may reduce the time to
frequency lock to a new reference by up to 2
seconds. However, this may cause an unnecessary
phase shift of up to 360° when the new and old
references are very close in frequency and phase.
0
1
T0 DPLL automatically determines frequency lock
enable.
T0 DPLL forced to always frequency and phase lock.
5
Not used.
-
-
4
resync_analog (analog dividers re-synchronization)
The analog output dividers include a
synchronization mechanism to ensure phase lock at
low frequencies between the input and the output.
0
Analog divider only synchronized during first 2
seconds after power-up.
Analog dividers always synchronized.This keeps the
clocks divided down from the APLL output, in sync
with equivalent frequency digital clocks in the DPLL.
Hence ensuring that 6.48 MHz output clocks, and
above, are in sync with the DPLL even though only a
77.76 MHz clock drives the APLL.
3
Test Control
Leave unchanged or set to 0
0
-
2
8k Edge Polarity
When lock 8k mode is selected for the current input
reference source, this bit allows the system to lock
on either the rising or the falling edge of the input
clock.
0
1
Lock to falling clock edge.
Lock to rising clock edge.
1
Test Control
Leave unchanged or set to zero
0
-
0
Test Control
Leave unchanged or set to zero
0
-
Revision 3.02/October 2005 © Semtech Corp.
Page 58
1
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 05
Register Name
sts_interrupts
Bit 7
I8
Bit No.
Description
Bit 6
I7
FINAL
Bit 5
I6
DATASHEET
(R/W) Bits [7:0] of the interrupt
status register.
Bit 4
Bit 3
I5
I4
Description
Bit 2
I3
Bit Value
Default Value
1111 1111
Bit 1
I2
Bit 0
I1
Value Description
7
I8
Interrupt indicating that input I8 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I8 has not changed status (valid/invalid).
Input I8 has changed status (valid/invalid).
Writing 1 resets the input to 0.
6
I7
Interrupt indicating that input I7 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I7 has not changed status (valid/invalid).
Input I7 has changed status (valid/invalid).
Writing 1 resets the input to 0.
5
I6
Interrupt indicating that input I6 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I6 has not changed status (valid/invalid).
Input I6 has changed status (valid/invalid).
Writing 1 resets the input to 0.
4
I5
Interrupt indicating that input I5 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I5 has not changed status (valid/invalid).
Input I5 has changed status (valid/invalid).
Writing 1 resets the input to 0.
3
I4
Interrupt indicating that input I4 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I4 has not changed status (valid/invalid).
Input I4 has changed status (valid/invalid).
Writing 1 resets the input to 0.
2
I3
Interrupt indicating that input I3 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I3 has not changed status (valid/invalid).
Input I3 has changed status (valid/invalid).
Writing 1 resets the input to 0.
1
I2
Interrupt indicating that input I2 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I2 has not changed status (valid/invalid).
Input I2 has changed status (valid/invalid).
Writing 1 resets the input to 0.
0
I1
Interrupt indicating that input I1 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I1 has not changed status (valid/invalid).
Input I1 has changed status (valid/invalid).
Writing 1 resets the input to 0.
Revision 3.02/October 2005 © Semtech Corp.
Page 59
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 06
Register Name
Bit 7
operating_
mode
Bit No.
sts_interrupts
Bit 6
FINAL
Description
Bit 5
main_ref_failed I14
DATASHEET
(R/W) bits [15:8] of the interrupt
status register.
Bit 4
Bit 3
I13
I12
Description
Bit 2
I11
Bit Value
Default Value
0011 1111
Bit 1
Bit 0
I10
I9
Value Description
7
operating_mode
Interrupt indicating that the operating mode has
changed. Latched until reset by software writing a 1
to this bit.
0
1
Operating mode has not changed.
Operating mode has changed.
Writing 1 resets the input to 0.
6
main_ref_failed
Interrupt indicating that input to the T0 DPLL has
failed. This interrupt will be raised after 2 missing
input cycles. This is much quicker than waiting for
the input to become invalid. This input is not
generated in Free-run or Holdover modes. Latched
until reset by software writing a 1 to this bit.
0
1
Input to the T0 DPLL is valid.
Input to the T0 DPLL has failed.
Writing 1 resets the input to 0.
5
I14
Interrupt indicating that input I14 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I14 has not changed status (valid/invalid).
Input I14 has changed status (valid/invalid).
Writing 1 resets the input to 0.
4
I13
Interrupt indicating that input I13 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I13 has not changed status (valid/invalid).
Input I13 has changed status (valid/invalid).
Writing 1 resets the input to 0.
3
I12
Interrupt indicating that input I12 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I12 has not changed status (valid/invalid).
Input I12 has changed status (valid/invalid).
Writing 1 resets the input to 0.
2
I11
Interrupt indicating that input I11 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I11 has not changed status (valid/invalid).
Input I11 has changed status (valid/invalid).
Writing 1 resets the input to 0.
1
I10
Interrupt indicating that input I10 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I10 has not changed status (valid/invalid).
Input I10 has changed status (valid/invalid).
Writing 1 resets the input to 0.
0
I9
Interrupt indicating that input I9 has become valid
(if it was invalid), or invalid (if it was valid). Latched
until reset by software writing a 1 to this bit.
0
1
Input I9 has not changed status (valid/invalid).
Input I9 has changed status (valid/invalid).
Writing 1 resets the input to 0.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 07
Register Name
sts_current_DPLL_frequency
[18:16]
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(RO) Bits [18:16] of the current
DPLL frequency.
Bit 4
Bit 3
Default Value
Bit 2
0000 0000
Bit 1
Bit 0
sts_current_DPLL_frequency[18:16]
Bit No.
Description
Bit Value
Value Description
[7:3]
Not used.
-
-
[2:0]
sts_current_DPLL_frequency[18:16]
When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the frequency
for the T0 path is reported.
When this Bit 4 = 1 the frequency for the T4 path is
reported.
-
See register description of
sts_current_DPLL_frequency at address 0D hex.
Address (hex): 08
Register Name
Bit 7
Sync_ip_alarm
Bit No.
sts_interrupts
Bit 6
Description
Bit 5
T4_status
(R/W) Bits [23:16] of the interrupt Default Value
status register.
0101 0000
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
T4_inputs_
failed
AMI2_Viol
AMI2_LOS
AMI1_Viol
AMI1_LOS
Description
Bit Value
Value Description
7
Sync_ip_alarm
Interrupt indicating that the Frame Sync input
monitor has hit its alarm limit. Latched until reset by
software writing a 1 to this bit.
0
1
Input Frame Sync alarm has not occurred.
Input Frame Sync alarm has occurred.
Writing 1 resets the input to 0.
6
T4_status
Interrupt indicating that the T4 DPLL has lost lock (if
it was locked) or gained lock (if it was not locked).
Latched until reset by software writing a 1 to this bit.
0
1
Input to the T4 DPLL has not changed.
Input to the T4 DPLL has lost/gained lock.
Writing 1 resets the input to 0.
5
Not used.
-
-
4
T4_inputs_failed
Interrupt indicating that no valid inputs are available
to the T4 DPLL. Latched until reset by software
writing a 1 to this bit.
0
1
T4 DPLL has valid inputs.
T4 DPLL has no valid inputs.
Writing 1 resets the input to 0.
3
AMI2_Viol
Interrupt indicating that an AMI Violation error has
occurred on input I2. Latched until reset by software
writing a 1 to this bit.
0
1
Input I2 has had no violation error.
Input I2 has had a violation error.
Writing 1 resets the input to 0.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 08 (cont...)
Register Name
sts_interrupts
Bit 7
Sync_ip_alarm
Bit No.
Bit 6
FINAL
Description
Bit 5
T4_status
DATASHEET
(R/W) Bits [23:16] of the interrupt Default Value
status register.
0101 0000
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
T4_inputs_
failed
AMI2_Viol
AMI2_LOS
AMI1_Viol
AMI1_LOS
Description
Bit Value
Value Description
2
AMI2_LOS
Interrupt indicating that an AMI LOS error has
occurred on input I2. Latched until reset by software
writing a 1 to this bit.
0
1
Input I2 has had no LOS error.
Input I2 has had a LOS error.
Writing 1 resets the input to 0.
1
AMI1_Viol
Interrupt indicating that an AMI Violation error has
occurred on input I1. Latched until reset by software
writing a 1 to this bit.
0
1
Input I1 has had no violation error.
Input I1 has had a violation error.
Writing 1 resets the input to 0.
0
AMI1_LOS
Interrupt indicating that an AMI LOS error has
occurred on input I1. Latched until reset by software
writing a 1 to this bit.
0
1
Input I1 has had no LOS error.
Input I1 has had a LOS error.
Writing 1 resets the input to 0.
Address (hex): 09
Register Name
sts_operating
Description
(RO) Current operating state of
the device’s internal state
machine.
Bit 7
Bit 6
Bit 5
Bit 4
SYNC2K_alarm
T4_DPLL_Lock
T0_DPLL_freq_
soft_alarm
T4_DPLL_freq_
soft_alarm
Bit No.
7
Bit 3
Description
Revision 3.02/October 2005 © Semtech Corp.
Page 62
Bit 2
0100 0001
Bit 1
Bit 0
T0_DPLL_operating_mode
Bit Value
SYNC2K_alarm
Reports current status of the external Sync monitor
alarm.
Default Value
0
1
Value Description
External Sync monitor not in alarm condition.
External Sync monitor in alarm condition.
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ACS8520 SETS
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Address (hex): 09 (cont...)
Register Name
sts_operating
FINAL
Description
(RO) Current operating state of
the device’s internal state
machine.
Bit 7
Bit 6
Bit 5
Bit 4
SYNC2K_alarm
T4_DPLL_Lock
T0_DPLL_freq_
soft_alarm
T4_DPLL_freq_
soft_alarm
Bit No.
6
DATASHEET
Bit 3
Description
Bit 2
0100 0001
Bit 1
Bit 0
T0_DPLL_operating_mode
Bit Value
T4_DPLL_Lock
Reports current phase lock status of the T4 DPLL.
The T4 DPLL does not have the same state machine
as the T0 DPLL, as it does not support all the
features of the TO DPLL. It can only report its state
as locked or unlocked.
Default Value
0
1
Value Description
T4 DPLL not phase locked to reference source.
T4 DPLL phase locked to reference source.
The bit indicates that the T4 DPLL is locked by
monitoring the T4 DPLL phase loss indicators, which
potentially come from four sources. The four phase
loss indicators are enabled by the same registers
that enable them for the T0 DPLL, as follows: the
fine phase loss detector enabled by Reg. 73 Bit 7,
the coarse phase loss detector enabled by Reg. 74
Bit 7, the phase loss indication from no activity on
the input enabled by Reg. 73 Bit 6 and phase loss
from the DPLL being at its minimum or maximum
frequency limits enabled by Reg. 4D Bit 7. For the
T4 DPLL lock indicator (at Reg. 09 Bit 6) the bit will
latch an indication of phase lost from the coarse
phase lock detector such that when an indication of
phase lost (or not locked) is set it stays in that
phase lost or not locked state (so Reg. 09 Bit 6 =0).
For this bit to give a correct current reading of the
T4 DPLL locked state, then the coarse phase loss
detector should be temporarily disabled (set
Reg. 74 Bit 7 = 0), then the T4 locked bit can be
read (Reg. 09 Bit 6), then the coarse phase loss
detector should be re-enabled again (set
Reg. 74 Bit 7 = 1).
Once the bit is indicating “locked” (Reg. 09 Bit 6=1),
it is always a correct indication and no change to
the coarse phase loss detector enable is required. If
at any time any cycle slips occur that trigger the
coarse phase loss detector (which monitors cycle
slips) then this information is latched so that the
lock bit (Reg. 09 Bit 6) will go low and stay low,
indicating that a problem has occurred. It is then a
requirement that the coarse phase loss detector's
disable/re-enable sequence is performed during a
read of the T4 locked bit, in order to get a current
indication of whether the T4 DPLL is locked.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Address (hex): 09 (cont...)
Register Name
sts_operating
FINAL
Description
(RO) Current operating state of
the device’s internal state
machine.
Bit 7
Bit 6
Bit 5
Bit 4
SYNC2K_alarm
T4_DPLL_Lock
T0_DPLL_freq_
soft_alarm
T4_DPLL_freq_
soft_alarm
Bit No.
5
4
3
[2:0]
DATASHEET
Bit 3
Description
T0_DPLL_freq_soft_alarm
The T0 DPLL has a programmable frequency limit
and “soft” alarm limit. The frequency limit is the
extent to which it will track a reference before
limiting. The “soft” limit is the point beyond which
the DPLL tracking a reference will cause an alarm.
This bit reports the status of the “soft” alarm.
0
T4_DPLL_freq_soft_alarm
The T4 DPLL has a programmable frequency limit
and “soft” alarm limit. The frequency limit is the
extent to which it will track a reference before
limiting. The “soft” limit is the point beyond which
the DPLL tracking a reference will cause an alarm.
This bit reports the status of the “soft” alarm.
0
Not used.
-
Revision 3.02/October 2005 © Semtech Corp.
Page 64
Bit 2
0100 0001
Bit 1
Bit 0
T0_DPLL_operating_mode
Bit Value
T0_DPLL_operating_mode
This field is used to report the state of the internal
finite state machine controlling the T0 DPLL.
Default Value
1
1
000
001
010
011
100
101
110
111
Value Description
T0 DPLL tracking its reference within the limits of
the programmed “soft” alarm.
T0 DPLL tracking its reference beyond the limits of
the programmed “soft” alarm.
T4 DPLL tracking its reference within the limits of
the programmed “soft” alarm.
T4 DPLL tracking its reference beyond the limits of
the programmed “soft” alarm.
Not used.
Free Run.
Holdover.
Not used.
Locked.
Pre-locked2.
Pre-locked.
Phase Lost.
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ACS8520 SETS
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Address (hex): 0A
Register Name
sts_priority_table
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(RO) Bits [7:0] of the validated
priority table.
Bit 4
Bit 3
Highest priority validated source
Bit No.
[7:4]
Description
Bit Value
Highest priority validated source
Reports the input channel number of the highest
priority validated source.
Note...If an input is valid and it does not appear in
this field when otherwise it might, then the input
may have been disallowed in Reg. 30 and Reg. 31
(cnfg_sts_remote_sources_valid).
Currently selected source
Reports the input channel number of the currently
selected source. When in Non-revertive mode, this
is not necessarily the same as the highest priority
validated source.
Note...If an input is valid and it does not appear in
this field when otherwise it might, then the input
may have been disallowed in Reg. 30 and Reg. 31
(cnfg_sts_remote_sources_valid).
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the currently
selected source for the T0 path is reported.
When this Bit 4 = 1 the currently selected source for
the T4 path is reported. The T4 path does not have
a Non-revertive mode so this will always be the
same as the highest priority validated source.
Revision 3.02/October 2005 © Semtech Corp.
Bit 2
Bit 1
0000 0000
Bit 0
Currently selected source
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the highest
priority validated source for the T0 path is reported.
When this Bit 4 = 1 the highest priority validated
source for the T4 path is reported.
[3:0]
Default Value
Page 65
Value Description
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
No valid source available.
Input I1 is the highest priority valid source.
Input I2 is the highest priority valid source.
Input I3 is the highest priority valid source.
Input I4 is the highest priority valid source.
Input I5 is the highest priority valid source.
Input I6 is the highest priority valid source.
Input I7 is the highest priority valid source.
Input I8 is the highest priority valid source.
Input I9 is the highest priority valid source.
Input I10 is the highest priority valid source.
Input I11 is the highest priority valid source.
Input I12 is the highest priority valid source.
Input I13 is the highest priority valid source.
Input I14 is the highest priority valid source.
Not used.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
No source currently selected.
Input I1 is the currently selected source.
Input I2 is the currently selected source.
Input I3 is the currently selected source.
Input I4 is the currently selected source.
Input I5 is the currently selected source.
Input I6 is the currently selected source.
Input I7 is the currently selected source.
Input I8 is the currently selected source.
Input I9 is the currently selected source.
Input I10 is the currently selected source.
Input I11 is the currently selected source.
Input I12 is the currently selected source.
Input I13 is the currently selected source.
Input I14 is the currently selected source.
Not used.
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ACS8520 SETS
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Address (hex): 0B
Register Name
sts_priority_table
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(RO) Bits [15:8] of the validated
priority table.
Bit 4
Bit 3
3rd highest priority validated source
Bit No.
[7:4]
Description
Bit Value
3rd highest priority validated source
Reports the input channel number of the 3rd highest
priority validated source.
Note...If an input is valid and it does not appear in
this field when otherwise it might, then the input
may have been disallowed in Reg. 30 and Reg. 31
(cnfg_sts_remote_sources_valid).
2nd highest priority validated
Reports the input channel number of the 2nd
highest priority validated source.
Note...If an input is valid and it does not appear in
this field when otherwise it might, then the input
may have been disallowed in Reg. 30 and Reg. 31
(cnfg_sts_remote_sources_valid).
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the 2nd highest
priority validated source for the T0 path is reported.
When this Bit 4 = 1 the 2nd highest priority validated
source for the T4 path is reported.
Revision 3.02/October 2005 © Semtech Corp.
Bit 2
0000 0000
Bit 1
Bit 0
2nd highest priority validated source
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the 3rd highest
priority validated source for the T0 path is reported.
When this Bit 4 = 1 the value will always be zero as
the T4 path does not maintain the 3rd highest
priority validated source.
[3:0]
Default Value
Page 66
Value Description
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Less than 3 valid sources available.
Input I1 is the 3rd highest priority valid source.
Input I2 is the 3rd highest priority valid source.
Input I3 is the 3rd highest priority valid source.
Input I4 is the 3rd highest priority valid source.
Input I5 is the 3rd highest priority valid source.
Input I6 is the 3rd highest priority valid source.
Input I7 is the 3rd highest priority valid source.
Input I8 is the 3rd highest priority valid source.
Input I9 is the 3rd highest priority valid source.
Input I10 is the 3rd highest priority valid source.
Input I11 is the 3rd highest priority valid source.
Input I12 is the 3rd highest priority valid source.
Input I13 is the 3rd highest priority valid source.
Input I14 is the 3rd highest priority valid source.
Not used.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Less than 2 valid sources available.
Input I1 is the 2nd highest priority valid source.
Input I2 is the 2nd highest priority valid source.
Input I3 is the 2nd highest priority valid source.
Input I4 is the 2nd highest priority valid source.
Input I5 is the 2nd highest priority valid source.
Input I6 is the 2nd highest priority valid source.
Input I7 is the 2nd highest priority valid source.
Input I8 is the 2nd highest priority valid source.
Input I9 is the 2nd highest priority valid source.
Input I10 is the 2nd highest priority valid source.
Input I11 is the 2nd highest priority valid source.
Input I12 is the 2nd highest priority valid source.
Input I13 is the 2nd highest priority valid source.
Input I14 is the 2nd highest priority valid source.
Not used.
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ACS8520 SETS
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Address (hex): 0C
Register Name
sts_current_DPLL_frequency
[7:0]
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(RO) Bits [7:0] of the current DPLL Default Value
frequency.
Bit 4
Bit 3
Bit 2
Bit 1
0000 0000
Bit 0
Bits [7:0] of sts_current_DPLL_frequency
Bit No.
[7:0]
Description
Bit Value
Bits [7:0] of sts_current_DPLL_frequency
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the frequency
for the T0 path is reported.
When this Bit 4 = 1 the frequency for the T4 path is
reported.
-
Value Description
See register description of
sts_current_DPLL_frequency at address 0D hex.
Address (hex): 0D
Register Name
Bit 7
sts_current_DPLL_frequency
[15:8]
Bit 6
Bit 5
Description
(RO) Bits [15:8] of the current
DPLL frequency.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
sts_current_DPLL_frequency[15:8]
Bit No.
[7:0]
Description
Bit Value
sts_current_DPLL_frequency[15:8]
This value in this register is combined with the value
in Reg. 0C and Reg. 07 to represent the current
frequency offset of the DPLL.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the frequency
for the T0 path is reported.
When this Bit 4 = 1 the frequency for the T4 path is
reported.
Revision 3.02/October 2005 © Semtech Corp.
Page 67
-
Value Description
In order to calculate the ppm offset of the DPLL with
respect to the crystal oscillator frequency, the value
in Reg. 07, Reg. 0D and Reg. 0C need to be
concatenated. This value is a 2’s complement
signed integer. The value multiplied by
0.0003068 dec will give the value in ppm offset
with respect to the XO frequency, allowing for any
crystal calibration that has been performed, via
cnfg_nominal_frequency, Reg. 3C and 3D. The
value is actually the DPLL integral path value so it
can be viewed as an average frequency, where the
rate of change is related to the DPLL bandwidth. If
Bit 3 of Reg. 3B is High then this value will freeze if
the DPLL has been pulled to its min or max
frequency.
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Address (hex): 0E
Register Name
sts_sources_valid
Bit 7
I8
Bit 6
I7
Bit No.
FINAL
Description
Bit 5
I6
DATASHEET
(RO) 8 least significant bits of the Default Value
sts_sources_valid register.
Bit 4
Bit 3
I5
I4
Description
Bit 2
I3
0
1
Input I8 is invalid.
Input I8 is valid.
6
I7
Bit indicating if I7 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I7 is invalid.
Input I7 is valid.
5
I6
Bit indicating if I6 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I6 is invalid.
Input I6 is valid.
4
I5
Bit indicating if I5 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I5 is invalid.
Input I5 is valid.
3
I4
Bit indicating if I4 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I4 is invalid.
Input I4 is valid.
2
I3
Bit indicating if I3 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I3 is invalid.
Input I3 is valid.
1
I2
Bit indicating if I2 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I2 is invalid.
Input I2 is valid.
0
I1
Bit indicating if I1 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I1 is invalid.
Input I1 is valid.
Page 68
I2
Value Description
I8
Bit indicating if I8 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
Revision 3.02/October 2005 © Semtech Corp.
Bit 1
Bit Value
7
0000 0000
Bit 0
I1
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Address (hex): 0F
Register Name
Bit 7
sts_sources_valid
Bit 6
Description
Bit 5
I14
Bit No.
[7:6]
FINAL
DATASHEET
(RO) 8 most significant bits of the Default Value
sts_sources_valid register.
Bit 4
Bit 3
I13
I12
Description
Bit 2
I11
Bit Value
Bit 1
I10
-
-
5
I14
Bit indicating if I14 is valid. The input is valid if
either it has no outstanding alarms, or it only has a
soft frequency alarm.
0
1
Input I14 is invalid.
Input I14 is valid.
4
I13
Bit indicating if I13 is valid. The input is valid if
either it has no outstanding alarms, or it only has a
soft frequency alarm.
0
1
Input I13 is invalid.
Input I13 is valid.
3
I12
Bit indicating if I12 is valid. The input is valid if
either it has no outstanding alarms, or it only has a
soft frequency alarm.
0
1
Input I12 is invalid.
Input I12 is valid.
2
I11
Bit indicating if I11 is valid. The input is valid if
either it has no outstanding alarms, or it only has a
soft frequency alarm.
0
1
Input I11 is invalid.
Input I11 is valid.
1
I10
Bit indicating if I10 is valid. The input is valid if
either it has no outstanding alarms, or it only has a
soft frequency alarm.
0
1
Input I10 is invalid.
Input I10 is valid.
0
I9
Bit indicating if I9 is valid. The input is valid if either
it has no outstanding alarms, or it only has a soft
frequency alarm.
0
1
Input I9 is invalid.
Input I9 is valid.
Page 69
Bit 0
I9
Value Description
Not used.
Revision 3.02/October 2005 © Semtech Corp.
0000 0000
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Address (hex): 10
Register Name
sts_reference_sources
Input pairs (1 & 2)
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(RO except for test when R/W)
Reports any alarms active on
inputs.
Bit 4
Bit 3
Address 10: Status of I2 Input
Address 11: Status of I4 Input
Address 12: Status of I6 Input
Address 13: Status of I8 Input
Address 14: Status of I10 Input
Address 15: Status of I12 Input
Address 16: Status of I14 Input
Default Value
Bit 2
0110 0110
Bit 1
Bit 0
Address 10: Status of I1 Input
Address 11: Status of I3 Input
Address 12: Status of I5 Input
Address 13: Status of I7 Input
Address 14: Status of I9 Input
Address 15: Status of I11 Input
Address 16: Status of I13 Input
Bit No.
Description
7&3
Out-of-band alarm (soft)
Soft out of band alarm bit for input. A “soft” alarm
will not invalidate an input.
0
1
No alarm.
Alarm armed. Alarm thresholds (range) set by
Reg. 49, or by Reg. 4A, Bits [7:4] if the input is
currently selected.
6&2
Out-of-band alarm (hard)
Hard out of band alarm bit for input. A “hard” alarm
will invalidate an input.
0
1
No alarm.
Alarm armed. Alarm thresholds set by Reg. 49 Bits
[3:0], or by Reg. 4A Bits [3:0] if the input is currently
selected.
5&1
No activity alarm
Alarm indication from the activity monitors.
0
1
No alarm.
Input has an active no activity alarm.
4&0
Phase lock alarm
If the DPLL can not indicate that it is phase locked
onto the current source within 100 seconds this
alarm will be raised.
0
1
No alarm.
Phase lock alarm.
Address (hex): 11
Address (hex): 12
Address (hex): 13
Address (hex): 14
Address (hex): 15
Address (hex): 16
Bit Value
Value Description
As Reg. 10, but for sts_reference_sources, Input pairs (3 & 4)
As Reg. 10, but for sts_reference_sources, Input pairs (5 & 6)
As Reg. 10, but for sts_reference_sources, Input pairs (7 & 8)
As Reg. 10, but for sts_reference_sources, Input pairs (9 & 10)
As Reg. 10, but for sts_reference_sources, Input pairs (11 & 12)
As Reg. 10, but for sts_reference_sources, Input pairs (13 & 14)
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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Address (hex): 18
Register Name
cnfg_ref_selection_priority
(1 & 2)
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Configures the relative
Default Value
priority of input sources I1 and I2.
(T0)* 0011 0010
(T4)* 0000 0000
Bit 4
Bit 3
cnfg_ref_selection_priority_2
Bit No.
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_1
Description
Bit Value
Value Description
[7:4]
cnfg_ref_selection_priority_2
This 4-bit value represents the relative priority of
input I2. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Input I2 unavailable for automatic selection.
Input I2 priority value.
[3:0]
cnfg_ref_selection_priority_1
This 4-bit value represents the relative priority of
input I1. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Input I1 unavailable for automatic selection.
Input I1 priority value.
Address (hex): 19
Register Name
Bit 7
cnfg_ref_selection_priority
(3 & 4)
Bit 6
Bit 5
Description
(R/W) Configures the relative
Default Value
priority of input sources I3 and I4.
(T0)* 0101 0100
(T4)* 0000 0000
Bit 4
Bit 3
cnfg_ref_selection_priority_4
Bit No.
[7:4]
Bit 1
Bit 0
cnfg_ref_selection_priority_3
Description
Bit Value
cnfg_ref_selection_priority_4
This 4-bit value represents the relative priority of
input I4. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
Revision 3.02/October 2005 © Semtech Corp.
Bit 2
0000
0001-1111
Page 71
Value Description
Input I4 unavailable for automatic selection.
Input I4 priority value.
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Address (hex): 19 (cont...)
Register Name
cnfg_ref_selection_priority
(3 & 4)
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Configures the relative
Default Value
priority of input sources I3 and I4.
(T0)* 0101 0100
(T4)* 0000 0000
Bit 4
Bit 3
cnfg_ref_selection_priority_4
Bit No.
[3:0]
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_3
Description
Bit Value
cnfg_ref_selection_priority_3
This 4-bit value represents the relative priority of
input I3. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Value Description
Input I3 unavailable for automatic selection.
Input I3 priority value.
Address (hex): 1A
Register Name
Bit 7
cnfg_ref_selection_priority
(5 & 6)
Bit 6
Bit 5
Description
(R/W) Configures the relative
Default Value
priority of input sources I5 and I6.
(T0)* 0111 0110
(T4)* 0111 0110
Bit 4
Bit 3
cnfg_ref_selection_priority_6
Bit No.
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_5
Description
Bit Value
Value Description
[7:4]
cnfg_ref_selection_priority_6
This 4-bit value represents the relative priority of
input I6. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Input I6 unavailable for automatic selection.
Input I6 priority value.
[3:0]
cnfg_ref_selection_priority_5
This 4-bit value represents the relative priority of
input I5. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Input I5 unavailable for automatic selection.
Input I5 priority value.
Revision 3.02/October 2005 © Semtech Corp.
Page 72
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Address (hex): 1B
Register Name
cnfg_ref_selection_priority
(7 & 8)
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Configures the relative
Default Value
priority of input sources I7 and I8.
(T0)* 1001 1000
(T4)* 1001 1000
Bit 4
Bit 3
cnfg_ref_selection_priority_8
Bit No.
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_7
Description
Bit Value
Value Description
[7:4]
cnfg_ref_selection_priority_8
This 4-bit value represents the relative priority of
input I8. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Input I8 unavailable for automatic selection.
Input I8 priority value.
[3:0]
cnfg_ref_selection_priority_7
This 4-bit value represents the relative priority of
input I7. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Input I7 unavailable for automatic selection.
Input I7 priority value.
Address (hex): 1C
Register Name
Bit 7
cnfg_ref_selection_priority
(9 & 10)
Bit 6
Bit 5
Description
(R/W) Configures the relative
priority of input sources I9 and
I10.
Bit 4
Bit 3
cnfg_ref_selection_priority_10
Bit No.
[7:4]
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_9
Description
Bit Value
cnfg_ref_selection_priority_10
This 4-bit value represents the relative priority of
input I10. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
Revision 3.02/October 2005 © Semtech Corp.
Default Value
(T0)* 1011 1010
(T4)* 1011 1010
0000
0001-1111
Page 73
Value Description
Input I10 unavailable for automatic selection.
Input I10 priority value.
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Address (hex): 1C (cont...)
Register Name
cnfg_ref_selection_priority
(9 & 10)
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Configures the relative
priority of input sources I9 and
I10.
Bit 4
Bit 3
cnfg_ref_selection_priority_10
Bit No.
[3:0]
Default Value
(T0)* 1011 1010
(T4)* 1011 1010
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_9
Description
Bit Value
cnfg_ref_selection_priority_9
This 4-bit value represents the relative priority of
input I9. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Value Description
Input I9 unavailable for automatic selection.
Input I9 priority value.
Address (hex): 1D
Register Name
Bit 7
cnfg_ref_selection_priority
(11 & 12)
Bit 6
Bit 5
Description
(R/W) Configures the relative
priority of input sources I11 and
I12.
Bit 4
Bit 3
cnfg_ref_selection_priority_12
Bit No.
[7:4]
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_11
Description
Bit Value
cnfg_ref_selection_priority_12
This 4-bit value represents the relative priority of
input I12. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
Revision 3.02/October 2005 © Semtech Corp.
Default Value
(T0)* 1101 1100
(T4)* 0000 0000
0000
0001-1111
Page 74
Value Description
Input I12 unavailable for automatic selection.
Input I12 priority value.
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Address (hex): 1D (cont...)
Register Name
cnfg_ref_selection_priority
(11 & 12)
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Configures the relative
priority of input sources I11 and
I12.
Bit 4
Bit 3
cnfg_ref_selection_priority_12
Bit No.
[3:0]
Default Value
(T0)* 1101 1100
(T4)* 0000 0000
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_11
Description
Bit Value
cnfg_ref_selection_priority_11
This 4-bit value represents the relative priority of
input I11. The smaller the number, the higher the
priority; zero disables the input.
*The priority of input I11 depends on the value of
the MASTSLVB pin at power-up. If MASTSLVB is High
(master) at power-up, then the priority will default to
12. If MASTSLVB is Low (slave) at power-up, then
the priority will default to 1.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Value Description
Input I11 unavailable for automatic selection.
Input I11 priority value.
.
Address (hex): 1E
Register Name
Bit 7
cnfg_ref_selection_priority
(13 & 14)
Bit 6
Bit 5
Description
(R/W) Configures the relative
priority of input sources I13 and
I14.
Bit 4
Bit 3
cnfg_ref_selection_priority_14
Bit No.
[7:4]
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_13
Description
Bit Value
cnfg_ref_selection_priority_14
This 4-bit value represents the relative priority of
input I14. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
Revision 3.02/October 2005 © Semtech Corp.
Default Value
(T0)* 1111 1110
(T4)* 0000 0000
0000
0001-1111
Page 75
Value Description
Input I14 unavailable for automatic selection.
Input I14 priority value.
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Address (hex): 1E (cont...)
Register Name
cnfg_ref_selection_priority
(13 & 14)
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Configures the relative
priority of input sources I13 and
I14.
Bit 4
Bit 3
cnfg_ref_selection_priority_14
Bit No.
Bit 2
Bit 1
Bit 0
cnfg_ref_selection_priority_13
Description
[3:0]
Default Value
(T0)* 1111 1110
(T4)* 0000 0000
Bit Value
cnfg_ref_selection_priority_13
This 4-bit value represents the relative priority of
input I13. The smaller the number, the higher the
priority; zero disables the input.
*When Bit 4 (T4_T0_select) of Reg. 4B
(cnfg_registers_source_select) = 0 the priority for
the T0 path is configured.
When this Bit 4 = 1 the priority for the T4 path is
configured.
0000
0001-1111
Value Description
Input I13 unavailable for automatic selection.
Input I13 priority value.
Address (hex): 20
Register Name
cnfg_ref_source_frequency
_1
Bit 7
Bit 6
Description
Bit 5
Set to zero
(R/W) Configuration of the
frequency and input monitoring
for input I1.
Bit 4
Bit 3
Default Value
Bit 2
bucket_id_1
Bit 1
0000 0000
Bit 0
Set to zero
Bit No.
Description
Bit Value
[7:6]
Set to zero
00
Set to zero
[5:4]
bucket_id_1
Every input has its own Leaky Bucket used for
activity monitoring. There are four possible
configurations for each Leaky Bucket- see Reg. 50
to 5F. This 2-bit field selects the configuration used
for input I1.
00
Input I1 activity monitor uses Leaky Bucket
Configuration 0.
Input I1 activity monitor uses Leaky Bucket
Configuration 1.
Input I1 activity monitor uses Leaky Bucket
Configuration 2.
Input I1 activity monitor uses Leaky Bucket
Configuration 3.
01
10
11
[3:0]
Set to zero
Revision 3.02/October 2005 © Semtech Corp.
0000
Page 76
Value Description
8 kHz only
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Address (hex): 21
Register Name
cnfg_ref_source_frequency
_2
Bit 7
Bit 6
FINAL
Description
Bit 5
Set to zero
DATASHEET
(R/W) Configuration of the
frequency and input monitoring
for input I2.
Bit 4
Bit 3
Default Value
Bit 2
bucket_id_2
0000 0000
Bit 1
Bit 0
Set to zero
Bit No.
Description
Bit Value
[7:6]
Set to zero
00
Set to zero
[5:4]
bucket_id_2
Every input has its own Leaky Bucket used for
activity monitoring. There are four possible
configurations for each Leaky Bucket- see Reg. 50
to Reg. 5F. This 2-bit field selects the configuration
used for input I2.
00
Input I2 activity monitor uses Leaky Bucket
Configuration 0.
Input I2 activity monitor uses Leaky Bucket
Configuration 1.
Input I2 activity monitor uses Leaky Bucket
Configuration 2.
Input I2 activity monitor uses Leaky Bucket
Configuration 3.
01
10
11
[3:0]
Set to zero
0000
Value Description
8 kHz only
Address (hex): 22
Use <n> = 3
Register Name
Bit 7
divn_<n>
Bit No.
cnfg_ref_source_frequency
_<n>, where for Reg 22, n =
3
Bit 6
lock8k_<n>
Bit 5
Description
(R/W) Configuration of the
frequency and input monitoring
for input I<n>.
Bit 4
Bit 3
bucket_id_<n>
Default Value
Bit 2
0000 0000
Bit 1
Bit 0
reference_source_frequency_<n>
Description
Bit Value
Value Description
7
divn_<n>
This bit selects whether or not input I<n> is divided
in the programmable pre-divider prior to being input
to the DPLL and frequency monitor- see Reg. 46
and Reg. 47 (cnfg_freq_divn).
0
1
Input I<n> fed directly to DPLL and monitor.
Input I<n> fed to DPLL and monitor via pre-divider.
6
lock8k_<n>
This bit selects whether or not input I<n> is divided
in the preset pre-divider prior to being input to the
DPLL. This results in the DPLL locking to the
reference after it has been divided to 8 kHz. This bit
is ignored when divn_<n> is set (bit =1).
0
1
Input I<n> fed directly to DPLL.
Input I<n> fed to DPLL via preset pre-divider.
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Address (hex): 22 (cont...)
FINAL
DATASHEET
Use <n> = 3
Register Name
cnfg_ref_source_frequency
_<n>, where for Reg 22, n =
3
Bit 7
divn_<n>
Bit No.
[5:4]
Bit 6
Description
Bit 5
lock8k_<n>
(R/W) Configuration of the
frequency and input monitoring
for input I<n>.
Bit 4
Bit 3
bucket_id_<n>
Description
Bit Value
bucket_id_<n>
Every input has its own Leaky Bucket used for
activity monitoring. There are four possible
configurations for each Leaky Bucket- see Reg. 50
to Reg. 5F. This 2-bit field selects the configuration
used for input I<n>.
reference_source_frequency_<n>
Programs the frequency of the reference source
connected to input I<n>. If divn_<n> is set, then
this value should be set to 0000 (8 kHz).
Address (hex): 23
Address (hex): 24
Address (hex): 25
Address (hex): 26
Address (hex): 27
Address (hex): 28
Address (hex): 29
Address (hex): 2A
Address (hex): 2B
Address (hex): 2C
Address (hex): 2D
Bit 2
0000 0000
Bit 1
Bit 0
reference_source_frequency_<n>
00
01
10
11
[3:0]
Default Value
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011-1111
Value Description
Input I<n> activity monitor uses Leaky Bucket
Configuration 0.
Input I<n> activity monitor uses Leaky Bucket
Configuration 1.
Input I<n> activity monitor uses Leaky Bucket
Configuration 2.
Input I<n> activity monitor uses Leaky Bucket
Configuration 3.
8 kHz.
1544/2048 kHz (dependant on Bit 2 (ip_sonsdhb)
in Reg. 34).
6.48 MHz.
19.44 MHz.
25.92 MHz.
38.88 MHz.
51.84 MHz.
77.76 MHz.
155.52 MHz.
2 kHz.
4 kHz.
Not used.
cnfg_ref_source_frequency_4
Use description for Reg. 22, but use <n> = 4
Default = 0000 0000
cnfg_ref_source_frequency_5
Use description for Reg. 22, but use <n> = 5
Default = 0000 0011
cnfg_ref_source_frequency_6
Use description for Reg. 22, but use <n> = 6
Default = 0000 0011
cnfg_ref_source_frequency_7
Use description for Reg. 22, but use <n> = 7
Default = 0000 0011
cnfg_ref_source_frequency_8
Use description for Reg. 22, but use <n> = 8
Default = 0000 0011
cnfg_ref_source_frequency_9
Use description for Reg. 22, but use <n> = 9
Default = 0000 0011
cnfg_ref_source_frequency_10
Use description for Reg. 22, but use <n> = 10
Default = 0000 0011
cnfg_ref_source_frequency_11
Use description for Reg. 22, but use <n> = 11
Default = 0000 0011
cnfg_ref_source_frequency_12
Use description for Reg. 22, but use <n> = 12
Default = 0000 0001
cnfg_ref_source_frequency_13
Use description for Reg. 22, but use <n> = 13
Default = 0000 0001
cnfg_ref_source_frequency_14
Use description for Reg. 22, but use <n> = 14
Default = 0000 0001
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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Address (hex): 30
Register Name
cnfg_sts_remote_sources_valid
Bit 7
I8
Bit 6
I7
Bit No.
FINAL
Description
Bit 5
I6
DATASHEET
(R/W) Bits [7:0] of the remote
sources valid register. A register
used to disable sources that are
invalid in another device in a
redundancy pair.
Bit 4
Bit 3
I5
I4
Description
Bit 2
I3
Bit Value
Default Value
Bit 1
I2
I8
Bit enabling input I8 to be considered for locking to.
If this bit is not set, then even if this input I8 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I8 disallowed.
Locking to input I8 allowed.
6
I7
Bit enabling input I7 to be considered for locking to.
If this bit is not set, then even if this input I7 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I7 disallowed.
Locking to input I7 allowed.
5
I6
Bit enabling input I6 to be considered for locking to.
If this bit is not set, then even if this input I6 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I6 disallowed.
Locking to input I6 allowed.
4
I5
Bit enabling input I5 to be considered for locking to.
If this bit is not set, then even if this input I5 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I5 disallowed.
Locking to input I5 allowed.
3
I4
Bit enabling input I4 to be considered for locking to.
If this bit is not set, then even if this input I4 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I4 disallowed.
Locking to input I4 allowed.
2
I3
Bit enabling input I3 to be considered for locking to.
If this bit is not set, then even if this input I3 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I3 disallowed.
Locking to input I3 allowed.
1
I2
Bit enabling input I2 to be considered for locking to.
If this bit is not set, then even if this input I2 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I2 disallowed.
Locking to input I2 allowed.
Page 79
Bit 0
I1
Value Description
7
Revision 3.02/October 2005 © Semtech Corp.
1111 1111
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Address (hex): 30 (cont...)
Register Name
cnfg_sts_remote_sources_valid
Bit 7
I8
Bit 6
I7
Bit No.
0
FINAL
Description
Bit 5
I6
DATASHEET
(R/W) Bits [7:0] of the remote
sources valid register. A register
used to disable sources that are
invalid in another device in a
redundancy pair.
Bit 4
Bit 3
I5
I4
Description
I1
Bit enabling input I1 to be considered for locking to.
If this bit is not set, then even if this input I1 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
Bit 2
I3
Bit Value
0
1
Default Value
1111 1111
Bit 1
I2
Bit 0
I1
Value Description
Locking to input I1 disallowed.
Locking to input I1 allowed.
Address (hex): 31
Register Name
Bit 7
cnfg_sts_remote_sources_valid
Bit 6
Bit 5
I14
Bit No.
[7:6]
Description
(R/W) Bits [13:8] of the remote
sources valid register. A register
used to disable source that are
invalid in another device in a
redundancy pair.
Bit 4
Bit 3
I13
I12
Description
Bit 2
I11
Bit Value
Default Value
Bit 1
I10
-
-
5
I14
Bit enabling input I14 to be considered for locking
to. If this bit is not set, then even if this input I14 is
valid, it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I14 disallowed.
Locking to input I14 allowed.
4
I13
Bit enabling input I13 to be considered for locking
to. If this bit is not set, then even if this input I13 is
valid, it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I13 disallowed.
Locking to input I13 allowed.
3
I12
Bit enabling input I12 to be considered for locking
to. If this bit is not set, then even if this input I12 is
valid, it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I12 disallowed.
Locking to input I12 allowed.
Page 80
Bit 0
I9
Value Description
Not used.
Revision 3.02/October 2005 © Semtech Corp.
0011 1111
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Address (hex): 31 (cont...)
Register Name
cnfg_sts_remote_sources_valid
Bit 7
Bit 6
Description
Bit 5
I14
Bit No.
FINAL
DATASHEET
(R/W) Bits [13:8] of the remote
sources valid register. A register
used to disable source that are
invalid in another device in a
redundancy pair.
Bit 4
Bit 3
I13
I12
Description
Bit 2
0011 1111
Bit 1
I11
Bit Value
Default Value
I10
Bit 0
I9
Value Description
2
I11
Bit enabling input I11 to be considered for locking
to. If this bit is not set, then even if this input I11 is
valid, it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I11 disallowed.
Locking to input I11 allowed.
1
I10
Bit enabling input I10 to be considered for locking
to. If this bit is not set, then even if this input I10 is
valid, it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I10 disallowed.
Locking to input I10 allowed.
0
I9
Bit enabling input I9 to be considered for locking to.
If this bit is not set, then even if this input I9 is valid,
it will still not appear in Reg. 0A and 0B
(sts_priority_table).
0
1
Locking to input I9 disallowed.
Locking to input I9 allowed.
Address (hex): 32
Register Name
Bit 7
cnfg_operating_mode
Bit 6
Description
Bit 5
(R/W) Register to force the state
of the TO DPLL controlling state
machine.
Bit 4
Bit 3
Default Value
Bit 2
0000 0000
Bit 1
Bit 0
T0_DPLL_operating_mode
Bit No.
[7:3]
Description
Bit Value
Not used.
Revision 3.02/October 2005 © Semtech Corp.
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Value Description
-
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ACS8520 SETS
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Address (hex): 32 (cont...)
Register Name
cnfg_operating_mode
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to force the state
of the TO DPLL controlling state
machine.
Bit 4
Bit 3
Default Value
Bit 2
0000 0000
Bit 1
Bit 0
T0_DPLL_operating_mode
Bit No.
[2:0]
Description
Bit Value
T0_DPLL_operating_mode
This field is used to control the state of the internal
finite state machine controlling the T0 DPLL. A value
of zero is used to allow the finite state machine to
control itself. Any other value will force the state
machine to jump into that state. Care should be
taken when forcing the state machine. Whilst it is
forced, the internal monitoring functions cannot
affect the internal state machine, therefore, the
user is responsible for all monitoring and control
functions required to achieve the desired
functionality.
000
001
010
011
100
101
110
111
Value Description
Automatic (internal state machine controlled).
Free Run.
Holdover.
Not used.
Locked.
Pre-locked2.
Pre-locked.
Phase Lost.
Address (hex): 33
Register Name
Bit 7
force_select_reference_source
Bit 6
Bit 5
Description
(R/W) Register used to force the Default Value
selection of a particular reference
source for the T0 DPLL.
Bit 4
Bit 3
Bit 2
Bit 1
0000 1111
Bit 0
forced_reference_source
Bit No.
Description
Bit Value
[7:4]
Not used.
[3:0]
forced_reference_source
Value representing the source to be selected by the
T0 DPLL. Value of 0 hex will leave the selection to
the automatic control mechanism within the device.
Using this mechanism will bypass all the monitoring
functions assuming the selected input to be valid. If
the device is not in state “Locked” then it will
progress to state locked in the usual manner. If the
input fails, the device will not change state to
Holdover, as it is not allowed to disqualify the
source. The effect of this register is simply to raise
the priority of the selected input to “1” (highest). To
ensure selection of the programmed input
reference under all circumstances, revertive mode
should be enabled (Reg. 34 bit 0 set to “1”).
Revision 3.02/October 2005 © Semtech Corp.
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Page 82
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Value Description
Automatic state machine source selection
T0 DPLL forced to select input I1.
T0 DPLL forced to select input I2.
T0 DPLL forced to select input I3.
T0 DPLL forced to select input I4.
T0 DPLL forced to select input I5.
T0 DPLL forced to select input I6.
T0 DPLL forced to select input I7.
T0 DPLL forced to select input I8.
T0 DPLL forced to select input I9.
T0 DPLL forced to select input I10.
T0 DPLL forced to select input I11.
T0 DPLL forced to select input I12.
T0 DPLL forced to select input I13.
T0 DPLL forced to select input I14.
Not used.
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Address (hex): 34
Register Name
cnfg_input_mode
Bit 7
Bit 6
auto_extsync_
en
Bit No.
7
phalarm_timeout
FINAL
Description
Bit 5
XO_edge
DATASHEET
(Bit 1 RO, otherwise R/W)
Register controlling various input
modes of the device.
Bit 4
Bit 3
man_holdover
extsync_en
Description
Bit Value
Default Value
Bit 2
ip_sonsdhb
Bit 1
master_slaveb
1100 0010*
Bit 0
reversion_mode
Value Description
auto_extsync_en
Bit to enable automatic enabling of the external
Frame Sync input when locked to source defined in
Reg. 7C Bits [3:0] (Sync_reference_source).
0
phalarm_timeout
Bit to enable the automatic time-out facility on
phase alarms. When enabled, any source with a
phase alarm set will have its phase alarm cancelled
after 128 seconds.
0
XO_edge
If the 12.800 MHz oscillator module connected to
REFCLK has one edge faster than the other, then for
jitter performance reasons, the faster edge should
be selected. This bit allows either the rising edge or
the falling edge to be selected.
0
4
man_holdover
Bit to select whether or not the Holdover frequency
is taken directly from Reg. 3E/Reg. 3F/Reg. 40
(cnfg_holdover_frequency). If this bit is set then it
overrides any other Holdover control bits.
0
1
Holdover frequency is determined automatically.
Holdover frequency is taken from
cnfg_holdover_frequency register.
3
extsync_en
Bit to select whether or not the T0 DPLL will look for
a reference Sync pulse on the SYNC2K input pin.
Even though this bit may enable the external Sync
reference, it may be disabled according to
auto_extsync_en.
0
1
No external Sync signal- SYNC2K pin ignored.
External Sync derived from SYNC2K pin according to
auto_extsync_en.
2
ip_sonsdhb
Bit to configure input frequencies to be either
SONET or SDH derived. This applies only to
selections of 0001 (bin) in the
cnfg_ref_source_frequency registers when the
input frequency is either 1544 kHz or 2048 kHz.
Note...this bit affects the SONET/SDH output on
TO9-refer to Reg. 64 Bit 4 and Reg. 35 Bit 4.
0
1
SDH- inputs set to 0001 expected to be 2048 kHz.
SONET- inputs set to 0001 expected to be
1544 kHz.
6
5
1
1
1
External Frame Sync enabled/disabled according to
extsync_en.
External Frame Sync enabled if extsync_en = 1 AND
T0 DPLL locked to source assigned to
Sync_reference_source.
Phase alarms on sources only cancelled by
software.
Phase alarms on sources automatically time out.
Device uses the rising edge of the external
oscillator.
Device uses the falling edge of the external
oscillator.
*The default value of this bit is taken from the value
of the SONSDHB pin at power-up.
Revision 3.02/October 2005 © Semtech Corp.
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Address (hex): 34 (cont...)
Register Name
cnfg_input_mode
Bit 7
Bit 6
auto_extsync_
en
Bit No.
1
0
phalarm_timeout
FINAL
Description
Bit 5
XO_edge
DATASHEET
(Bit 1 RO, otherwise R/W)
Register controlling various input
modes of the device.
Bit 4
Bit 3
man_holdover
extsync_en
Description
Bit Value
master_slaveb (R/O)
Bit to reflect the value of the MASTSLVB pin.
*As this always reflects the value on the pin, the
default value of this bit will be according to the
value on the pin at power-up. For software control,
set MASTSLVB pin to Master mode at all times and
program the individual registers (as per Value
Description) to give Master or Slave mode
functionality.
0
reversion_mode
Bit to select Revertive/Non-revertive mode. When in
Non-revertive mode, the device will not
automatically switch to a higher priority source,
unless the current source fails. When in Revertive
mode the device will always select the highest
priority source.
0
1
1
Default Value
Bit 2
ip_sonsdhb
1100 0010*
Bit 1
Bit 0
master_slaveb
reversion_mode
Value Description
Slave mode.
I11 set to highest priority.
T0 DPLL set to acquisition bandwidth.
Revertive mode enabled.
Phase Build-out disabled.
Master mode.
I11 priority, T0 DPLL bandwidth, Revertive mode,
Phase Build-out, all as programmed in the registers.
Non-revertive mode.
Revertive mode.
Address (hex): 35
Register Name
Bit 7
lock_T4_to_T0
Bit No.
cnfg_T4_path
Bit 6
Description
Bit 5
T4_dig_feedback
Register to configure the inputs
Default Value
and other features in the T4 path.
Bit 4
Bit 3
Bit 2
T4_op_from_T0
Description
0100 0000
Bit 1
Bit 0
T4_forced_reference_source
Bit Value
Value Description
7
lock_T4_to_T0
Bit selects either the T4 direct inputs, or T0 DPLL as
the input of the T4 path. This allows the T4 DPLL to
be used to produce different sets of frequencies to
the T0 DPLL but still maintain lock.
0
1
T4 path locks independently from the T0 path.
T4 DPLL locks to the output of the T0 DPLL.
6
T4_dig_feedback
Bit to select digital feedback mode for the T4 DPLL.
0
1
T4 DPLL in analog feedback mode.
T4 DPLL in digital feedback mode.
5
Not used.
-
-
4
T4_op_from_T0
0
1
T08 and T09 will be generated from T4 DPLL
T08 and T09 will be generated from T0 DPLL
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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Address (hex): 35 (cont...)
Register Name
cnfg_T4_path
Bit 7
lock_T4_to_T0
Bit No.
[3:0]
Bit 6
FINAL
Description
Bit 5
T4_dig_feedback
DATASHEET
Register to configure the inputs
Default Value
and other features in the T4 path.
Bit 4
Bit 3
Bit 2
T4_op_from_T0
0100 0000
Bit 1
Bit 0
T4_forced_reference_source
Description
Bit Value
T4_forced_reference_source
This field can be used to force the T4 DPLL to select
a particular input. A value of zero in this field allows
the T4 input to be selected automatically via the
priority and input monitoring functions.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Value Description
T4 DPLL automatic source selection.
T4 DPLL forced to select input I1.
T4 DPLL forced to select input I2.
T4 DPLL forced to select input I3.
T4 DPLL forced to select input I4.
T4 DPLL forced to select input I5.
T4 DPLL forced to select input I6.
T4 DPLL forced to select input I7.
T4 DPLL forced to select input I8.
T4 DPLL forced to select input I9.
T4 DPLL forced to select input I10.
T4 DPLL forced to select input I11.
T4 DPLL forced to select input I12.
T4 DPLL forced to select input I13.
T4 DPLL forced to select input I14.
Not used.
Address (hex): 36
Register Name
Bit 7
cnfg_differential_inputs
Bit 6
Bit 5
Description
(R/W) Configures the differential
inputs to be PECL or LVDS type
inputs.
Bit 4
Bit 3
Default Value
Bit 2
0000 0010
Bit 1
Bit 0
I6_PECL
Bit No.
[7:2]
Description
Bit Value
I5_LVDS
Value Description
Not used.
-
-
1
I6_PECL
Configures the I6 input to be compatible with either
3 V LVDS or 3 V PECL electrical levels.
0
1
I6 input LVDS compatible.
I6 input PECL compatible (Default).
0
I5_LVDS
Configures the I5 input to be compatible with either
3 V LVDS or 3 V PECL electrical levels.
0
1
I5 input LVDS compatible (Default).
I5 input PECL compatible.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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Address (hex): 37
Register Name
cnfg_uPsel_pins
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(RO) Register reflecting the value
on the UPSEL device pins.
Bit 4
Bit 3
Default Value
Bit 2
0000 0010*
Bit 1
Bit 0
upsel_pins_value
Bit No.
Description
Bit Value
[7:3]
Not used.
-
[2:0]
upsel_pins_value
This register always reflects the value present on
the UPSEL pins of the device. At reset this is used to
set the mode of the microprocessor interface.
Following power-up, these pins have no further
effect on the microprocessor interface, hence it is
possible to use the pins and register combination as
a general purpose input for software.
*The default of this register is entirely dependent
on the value of the pins at reset.
000
001
010
011
100
101
110
111
(value at reset)
Value Description
Not used.
Interface in EPROM boot mode.
Interface in Multiplexed mode.
Interface in Intel mode.
Interface in Motorola mode.
Interface in Serial mode.
Not used.
Not used.
Address (hex): 38
Register Name
Bit 7
cnfg_dig_outputs_sonsdh
Bit 6
dig2_sonsdh
Bit No.
Bit 5
Description
Configures Digital1 and Digital2
output frequencies to be SONET
or SDH compatible frequencies.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0001 1111*
Bit 0
dig1_sonsdh
Description
Bit Value
Value Description
7
Not used.
-
-
6
dig2_sonsdh
Selects whether the frequencies generated by the
Digital2 frequency generator are SONET derived or
SDH.
*Default value of this bit is set by the SONSDHB pin
at power-up.
1
Digital2 can be selected from 1544/3088/6176/
12352 kHz.
Digital2 can be selected from 2048/4096/8192/
16384 kHz.
dig1_sonsdh
Selects whether the frequencies generated by the
Digital1 frequency generator are SONET derived or
SDH.
*Default value of this bit is set by the SONSDHB pin
at power-up.
1
Not used.
-
5
[4:0]
Revision 3.02/October 2005 © Semtech Corp.
Page 86
0
0
Digital1 can be selected from 1544/3088/6176/
12352 kHz.
Digital1 can be selected from 2048/4096/8192/
16384 kHz.
-
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Address (hex): 39
Register Name
cnfg_digtial_frequencies
Bit 7
Bit 6
Bit No.
Description
Bit 5
digital2_frequency
FINAL
DATASHEET
(R/W) Configures the actual
Default Value
frequencies of Digital1 & Digital2.
Bit 4
Bit 3
Bit 2
0000 1000
Bit 1
Bit 0
digital1_frequency
Description
Bit Value
Value Description
[7:6]
digital2_frequency
Configures the frequency of Digital2. Whether this is
SONET or SDH based is configured by Bit 6
(dig2_sonsdh) of Reg. 38.
00
01
10
11
Digital2 set to 1544 kHz or 2048 kHz.
Digital2 set to 3088 kHz or 4096 kHz.
Digital2 set to 6176 kHz or 8192 kHz.
Digital2 set to 12353 kHz or 16384 kHz.
[5:4]
digital1_frequency
Configures the frequency of Digital1. Whether this is
SONET or SDH based is configured by Bit 5
(dig1_sonsdh) of Reg. 38.
00
01
10
11
Digital1 set to 1544 kHz or 2048 kHz.
Digital1 set to 3088 kHz or 4096 kHz.
Digital1 set to 6176 kHz or 8192 kHz.
Digital1 set to 12353 kHz or 16384 kHz.
[3:0]
Not used.
Address (hex): 3A
Register Name
Bit 7
cnfg_differential_outputs
Bit 6
Bit 5
Description
(R/W) Configures the electrical
compatibility of the differential
output drivers to be 3 V PECL or
3 V LVDS.
Bit 4
Bit 3
Default Value
Bit 2
TO7_PECL_LVDS
Bit No.
Description
Bit Value
Bit 1
Bit 0
TO6_LVDS_PECL
Value Description
[7:4]
Not used.
[3:2]
TO7_PECL_LVDS
Selection of the electrical compatibility of TO7
between 3 V PECL and 3 V LVDS.
00
01
10
11
Output TO7 disabled.
Output T07 3 V PECL compatible.
Output TO7 3 V LVDS compatible.
Not used.
[1:0]
TO6_LVDS_PECL
Selection of the electrical compatibility of TO6
between 3 V PECL and 3 V LVDS.
00
01
10
11
Output TO6 disabled.
Output T06 3 V PECL compatible.
Output TO6 3 V LVDS compatible.
Not used.
Revision 3.02/October 2005 © Semtech Corp.
-
1100 0110
Page 87
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ACS8520 SETS
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Address (hex): 3B
Register Name
cnfg_auto_bw_sel
Bit 7
Bit 6
FINAL
Description
Bit 5
(R/W) Register to select
Default Value
automatic BW selection for the T0
DPLL path
Bit 4
Bit 3
7
[6:4]
3
[2:0]
Bit 2
1111 1011
Bit 1
Bit 0
T0_lim_int
auto_BW_sel
Bit No.
DATASHEET
Description
Bit Value
Value Description
auto_BW_sel
Bit to select locked bandwidth (Reg. 67) or
acquisition bandwidth (Reg. 69) for the T0 DPLL
1
0
Automatically selects either locked or acquisition
bandwidth as appropriate
Always selects locked bandwidth
Not used.
-
-
T0_lim_int
When set to 1 the integral path value of the DPLL is
limited or frozen when the DPLL reaches either min
or max frequency. This can be used to minimize
subsequent overshoot when the DPLL is pulling in.
Note that when this happens, the reported
frequency value via current_DPLL_freq (Reg. 0C, 0D
and 07) is also frozen.
1
0
DPLL value frozen
DPLL not frozen
Not used.
-
-
Address (hex): 3C
Register Name
Bit 7
cnfg_nominal_frequency
[7:0]
Bit 6
Description
Bit 5
(R/W) Bits [7:0] of the register
used to calibrate the crystal
oscillator used to clock the
device.
Bit 4
Bit 3
Default Value
Bit 2
1001 1001
Bit 1
Bit 0
cnfg_nominal_frequency_value[7:0]
Bit No.
[7:0]
Description
Bit Value
cnfg_nominal_frequency_value[7:0]
Revision 3.02/October 2005 © Semtech Corp.
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Page 88
Value Description
See register description of Reg. 3D
(cnfg_nominal_frequency_value[15:8]).
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Address (hex): 3D
Register Name
cnfg_nominal_frequency
[15:8]
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Bits [15:8] of the register
used to calibrate the crystal
oscillator used to clock the
device.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
1001 1001
Bit 0
cnfg_nominal_frequency_value[15:8]
Bit No.
[7:0]
Description
Bit Value
cnfg_nominal_frequency_value[15:8]
This register is used in conjunction with Reg. 3C
(cnfg_nominal_frequency_value[7:0]) to be able to
offset the frequency of the crystal oscillator by up to
+514 ppm and –771 ppm. The default value
represents 0 ppm offset from 12.800 MHz.
This value is an unsigned integer.
-
Value Description
In order to program the ppm offset of the crystal
oscillator frequency, the value in Reg. 3C and
Reg. 3D hex need to be concatenated. This value is
an unsigned integer. The value multiplied by
0.0196229 dec will give the value in ppm. To
calculate the absolute value, the default (39321)
needs to be subtracted.
The value in Reg. 3C/3D is used within the DPLL to
offset the frequency value used in the DPLL only.
This means that the value programmed will affect
the value reported in the
sts_current_DPLL_frequency (Reg 07/0D/0C). It
will also affect the value programmed into
holdover_frequency_value in the
cnfg_holdover_frequency register (Reg 3E/3F/40)
and the DPLL frequency offset limit programmed
into the cnfg_DPLL_freq_limit (Reg 41/42). It must
be noted, however, that this “calibrated” frequency
is NOT used in the frequency monitors affecting
Regs 49, 4A, 4C & 4D. These registers
(cnfg_freq_mon_threshold,
cnfg_current_freq_mon_ threshold,
sts_freq_measurement, cnfg_DPLL_soft_limit)
which all use the uncalibrated crystal frequency.
The frequency monitors can also use the clock from
the output of the DPLL by programming bit
freq_mon_clock in cnfg_monitors (Reg 48).
Address (hex): 3E
Register Name
Bit 7
cnfg_holdover_frequency
[7:0]
Bit 6
Bit 5
Description
(R/W) Bits [7:0] of the manual
Holdover frequency register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
holdover_frequency_value[7:0]
Bit No.
[7:0]
Description
Bit Value
holdover_frequency_value[7:0]
Revision 3.02/October 2005 © Semtech Corp.
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Value Description
See Reg. 3F (cnfg_holdover_frequency) for details.
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Address (hex): 3F
Register Name
cnfg_holdover_frequency
[15:8]
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Bits [15:8] of the manual
Holdover frequency register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
holdover_frequency_value[15:8]
Bit No.
[7:0]
Description
Bit Value
holdover_frequency_value[15:8]
This value in this register is combined with the value
in Reg. 3E and Bits [2:0] of Reg. 40 to represent the
programmed Holdover frequency of the T0 DPLL.
-
This register is designed such that software can
read the sts_current_DPLL_frequency register
(Reg. 0C, Reg. 0D and Reg. 07) and filter the value.
The result will then be in a suitable format to simply
write back to the cnfg_holdover_frequency register.
Value Description
In order to calculate the Holdover ppm offset of the
DPLL with respect to the crystal oscillator frequency,
the value in Reg. 3E hex and Bits [2:0] of Reg. 40
need to be concatenated. This value is a 2’s
complement signed integer. The value multiplied by
0.0003068 dec will give the value in ppm.
*This register can be programmed to read back the
internally averaged Holdover frequency rather than
the programmed value, see Bit 5 of Reg. 40
cnfg_holdover_modes.
Address (hex): 40
Register Name
Bit 7
cnfg_holdover_modes
Bit 6
auto_averaging fast_averaging
Bit No.
7
6
Description
Bit 5
read_average
(R/W) Register to control the
Holdover modes of the T0 DPLL.
Bit 4
Bit 3
mini_holdover_mode
Description
Bit Value
auto_averaging
Bit to enable the use of the averaged frequency
value during Holdover. This bit is overridden by the
manual Holdover control (Bit 4, man_holdover, in
Reg. 34).
0
fast_averaging
Bit to control the rate of averaging of the Holdover
frequency. Fast averaging gives a -3db response
point of approximately 8 minutes. Slow averaging
give a -3db response point of approximately 110
minutes.
0
1
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Default Value
Bit 2
Bit 1
1000 1000
Bit 0
holdover_frequency_value [18:16]
Value Description
Averaged frequency not used, Holdover frequency
either manual or instantaneously frozen.
Averaged frequency used, providing manual
Holdover mode is not engaged.
Slow Holdover frequency averaging enabled.
Fast Holdover frequency averaging enabled.
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Address (hex): 40 (cont...)
Register Name
Bit 7
cnfg_holdover_modes
Bit 6
auto_averaging fast_averaging
Bit No.
5
[4:3]
[2:0]
FINAL
Description
Bit 5
read_average
DATASHEET
(R/W) Register to control the
Holdover modes of the T0 DPLL.
Bit 4
Bit 3
mini_holdover_mode
Description
Bit Value
read_average
Bit to control whether the value read from the
holdover_frequency_value register is the value
written to that register, or the averaged Holdover
frequency. This allows software to use the internal
averager as part of the Holdover algorithm, but use
manual Holdover mode plus software to enhance
the performance.
0
mini_holdover_mode
Mini-holdover is a term used to describe the state of
the DPLL when it is in locked mode, but it has
temporarily lost its input. This may be a temporary
state, or last for many seconds whilst an input is
checked for inactivity. The DPLL behaves exactly as
in Holdover, and the frequency can be determined
in the same selection of ways (instantaneously, fast
averaged or slow averaged).
00
holdover_frequency_value [18:16]
Revision 3.02/October 2005 © Semtech Corp.
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Default Value
Bit 2
Bit 1
1000 1000
Bit 0
holdover_frequency_value [18:16]
Value Description
Value read from holdover_frequency_value is the
value written to it.
Value read from a holdover_frequency_value is
either the fast or slow averaged frequency as
determined by fast_averaging.
01
10
11
Mini-holdover frequency determined in the same
way as for full Holdover mode.
Mini-holdover frequency frozen instantaneously.
Mini-holdover frequency taken from fast averager.
Mini-holdover frequency taken from slow averager.
-
See Reg. 3F (cnfg_holdover_frequency) for details.
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Address (hex): 41
Register Name
cnfg_DPLL_freq_limit
[7:0]
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Bits [7:0] of the DPLL
frequency limit register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0111 0110
Bit 0
DPLL_freq_limit_value[7:0]
Bit No.
[7:0]
Description
Bit Value
DPLL_freq_limit_value[7:0]
This register defines the extent of frequency offset
to which either the T0 or the T4 DPLL will track a
source before limiting- i.e. it represents the pull-in
range of the DPLLs. The offset of the device is
determined by the frequency offset of the DPLL
when compared to the offset of the external crystal
oscillator clocking the device. If the oscillator is
calibrated using cnfg_nominal_frequency Reg. 3C
and 3D, then this calibration is automatically taken
into account. The DPLL frequency limit limits the
offset of the DPLL when compared to the calibrated
oscillator frequency.
-
Value Description
In order to calculate the frequency limit in ppm,
Bits [1:0] of Reg. 42 and Bits [7:0] of Reg. 41 need
to be concatenated. This value is a unsigned integer
and represents limit both positive and negative in
ppm. The value multiplied by 0.078 will give the
value in ppm.
Address (hex): 42
Register Name
Bit 7
cnfg_DPLL_freq_limit
[9:8]
Bit 6
Description
Bit 5
(R/W) Bits [9:8] of the DPLL
frequency limit register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
DPLL_freq_limit_value[9:8]
Bit No.
Description
Bit Value
Value Description
[7:2]
Not used.
-
-
[1:0]
DPLL_freq_limit_value[9:8]
-
See Reg. 41 (cnfg_DPLL_freq_limit) for details.
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Address (hex): 43
Register Name
cnfg_interrupt_mask
[7:0]
Bit 7
I8
Bit 6
I7
Bit No.
FINAL
Description
Bit 5
I6
(R/W) Bits [7:0] of the interrupt
mask register.
Bit 4
I5
DATASHEET
Bit 3
I4
Description
Bit 2
I3
Bit Value
Default Value
0000 0000
Bit 1
I2
Bit 0
I1
Value Description
7
I8
Mask bit for input I8 interrupt.
0
1
Input I8 cannot generate interrupts.
Input I8 can generate interrupts.
6
I7
Mask bit for input I7 interrupt.
0
1
Input I7 cannot generate interrupts.
Input I7 can generate interrupts.
5
I6
Mask bit for input I6 interrupt.
0
1
Input I6 cannot generate interrupts.
Input I6 can generate interrupts.
4
I5
Mask bit for input I5 interrupt.
0
1
Input I5 cannot generate interrupts.
Input I5 can generate interrupts.
3
I4
Mask bit for input I4 interrupt.
0
1
Input I4 cannot generate interrupts.
Input I4 can generate interrupts.
2
I3
Mask bit for input I3 interrupt.
0
1
Input I3 cannot generate interrupts.
Input I3 can generate interrupts.
1
I2
Mask bit for input I2 interrupt.
0
1
Input I2 cannot generate interrupts.
Input I2 can generate interrupts.
0
I1
Mask bit for input I1 interrupt.
0
1
Input I1 cannot generate interrupts.
Input I1 can generate interrupts.
Address (hex): 44
Register Name
Bit 7
operating_
mode
Bit No.
cnfg_interrupt_mask
[15:8]
Bit 6
Description
Bit 5
main_ref_failed I14
(R/W) Bits [15:8] of the interrupt
mask register.
Bit 4
I13
Bit 3
I12
Description
Bit 2
I11
Bit Value
Default Value
0000 0000
Bit 1
I10
Bit 0
I9
Value Description
7
operating_mode
Mask bit for operating_mode interrupt.
0
1
Operating mode cannot generate interrupts.
Operating mode can generate interrupts.
6
main_ref_failed
Mask bit for main_ref_failed interrupt.
0
1
Main reference failure cannot generate interrupts.
Main reference failure can generate interrupts.
5
I14
Mask bit for input I14 interrupt.
0
1
Input I14 cannot generate interrupts.
Input I14 can generate interrupts.
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Address (hex): 44 (cont...)
Register Name
cnfg_interrupt_mask
[15:8]
Bit 7
operating_
mode
Bit No.
Bit 6
FINAL
Description
Bit 5
main_ref_failed I14
(R/W) Bits [15:8] of the interrupt
mask register.
Bit 4
I13
DATASHEET
Bit 3
I12
Description
Bit 2
I11
Bit Value
Default Value
0000 0000
Bit 1
I10
Bit 0
I9
Value Description
4
I13
Mask bit for input I13 interrupt.
0
1
Input I13 cannot generate interrupts.
Input I13 can generate interrupts.
3
I12
Mask bit for input I12 interrupt.
0
1
Input I12 cannot generate interrupts.
Input I12 can generate interrupts.
2
I11
Mask bit for input I11 interrupt.
0
1
Input I11 cannot generate interrupts.
Input I11 can generate interrupts.
1
I10
Mask bit for input I10 interrupt.
0
1
Input I10 cannot generate interrupts.
Input I10 can generate interrupts.
0
I9
Mask bit for input I9 interrupt.
0
1
Input I9 cannot generate interrupts.
Input I9 can generate interrupts.
Address (hex): 45
Register Name
Bit 7
Sync_ip_alarm
Bit No.
cnfg_interrupt_mask
[23:16]
Bit 6
Description
Bit 5
T4_status
(R/W) Bits [23:16] of the interrupt Default Value
mask register.
0000 0000
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
T4_inputs_
failed
AMI2_Viol
AMI2_LOS
AMI1_Viol
AMI1_LOS
Description
Bit Value
Value Description
7
Sync_ip_alarm
Mask bit for Sync_ip_alarm interrupt.
0
1
The external Sync input cannot generate interrupts.
The external Sync input can generate interrupts.
6
T4_status
Mask bit for T4_status interrupt.
0
1
Change in T4 status cannot generate interrupts.
Change in T4 status can generate interrupts.
5
Not used.
-
-
4
T4_inputs_failed
Mask bit for T4_inputs_failed interrupt.
0
1
Failure of T4 inputs cannot generate interrupts.
Failure of T4 inputs can generate interrupts.
3
AMI2_Viol
Mask bit for AMI2_Viol interrupt.
0
1
Input I2 cannot generate AMI violation interrupts.
Input I2 can generate AMI violation interrupts.
2
AMI2_LOS
Mask bit for AMI2_LOS interrupt.
0
1
Input I2 cannot generate AMI LOS interrupts.
Input I2 can generate AMI LOS interrupts.
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Address (hex): 45 (cont...)
Register Name
cnfg_interrupt_mask
[23:16]
Bit 7
Sync_ip_alarm
Bit No.
Bit 6
FINAL
Description
Bit 5
T4_status
DATASHEET
(R/W) Bits [23:16] of the interrupt Default Value
mask register.
0000 0000
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
T4_inputs_
failed
AMI2_Viol
AMI2_LOS
AMI1_Viol
AMI1_LOS
Description
Bit Value
Value Description
1
AMI1_Viol
Mask bit for AMI1_Viol interrupt.
0
1
Input I1 cannot generate AMI violation interrupts.
Input I1 can generate AMI violation interrupts.
0
AMI1_LOS
Mask bit for AMI1_LOS interrupt.
0
1
Input I1 cannot generate AMI LOS interrupts.
Input I1 can generate AMI LOS interrupts.
Address (hex): 46
Register Name
cnfg_freq_divn
[7:0]
Bit 7
Bit 6
Description
Bit 5
(R/W) Bits [7:0] of the division
factor for inputs using the DivN
feature.
Bit 4
Bit 3
Default Value
Bit 2
1111 1111
Bit 1
Bit 0
divn_value[7:0]
Bit No.
[7:0]
Description
Bit Value
divn_value[7:0]
-
Value Description
See Reg. 47 (cnfg_freq_divn) for details.
Address (hex): 47
Register Name
cnfg_freq_divn
[13:8]
Bit 7
Bit 6
Description
Bit 5
(R/W) Bits [13:8] of the division
factor for inputs using the DivN
feature.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0011 1111
Bit 0
divn_value[13:8]
Bit No.
[7:6]
Description
Bit Value
Not used.
Revision 3.02/October 2005 © Semtech Corp.
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Page 95
Value Description
-
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Address (hex): 47 (cont...)
Register Name
cnfg_freq_divn
[13:8]
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Bits [13:8] of the division
factor for inputs using the DivN
feature.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0011 1111
Bit 0
divn_value[13:8]
Bit No.
[5:0]
Description
Bit Value
divn_value[13:8]
This register, in conjunction with Reg. 46
(cnfg_freq_divn) represents the integer value by
which to divide inputs that use the DivN pre-divider.
The divn feature supports input frequencies up to a
maximum of 100 MHz; therefore, the maximum
value that should be written to this register is 30D3
hex (12499 dec). Use of higher DivN values may
result in unreliable behavior.
-
Value Description
The input frequency will be divided by the value in
this register plus 1. i.e. to divide by 8, program a
value of 7.
Address (hex): 48
Register Name
Bit 7
freq_mon_clk
Bit No.
cnfg_monitors
Bit 6
los_flag_on_
TDO
Description
Bit 5
Bit 4
ultra_fast_
switch
ext_switch
(R/W) Configuration register
Default Value
controlling several input
monitoring and switching options.
Bit 3
PBO_freeze
Description
Bit Value
Bit 2
PBO_en
Bit 1
freq_monitor_
soft_enable
0000 0101*
Bit 0
freq_monitor_
hard_enable
Value Description
7
freq_mon_clk
Bit to select the source of the clock to the frequency
monitors to be either from the output clock or
directly from the crystal oscillator.
0
1
Frequency monitors clocked by output of TO DPLL.
Frequency monitors clocked by crystal oscillator
frequency.
6
los_flag_on_TDO
Bit to select whether the main_ref_fail interrupt
from the T0 DPLL is flagged on the TDO pin. If
enabled this will not strictly conform to the IEEE
1149.1 JTAG standard for the function of the TDO
pin. When enabled the TDO pin will simply mimic the
state of the main_ref_fail interrupt status bit.
0
1
Normal mode, TDO complies with IEEE 1149.1.
TDO pin used to indicate the state of the
main_ref_fail interrupt status. This allows a system
to have a hardware indication of a source failure
very rapidly.
5
ultra_fast_switch
Bit to enable ultra-fast switching mode. When in this
mode, the device will disqualify a locked-to source
as soon as it detects a few missing input cycles.
0
Currently selected source only disqualified by Leaky
Bucket or frequency monitors.
Currently selected source disqualified after less
than 3 missing input cycles.
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Address (hex): 48 (cont...)
Register Name
Bit 7
freq_mon_clk
Bit No.
cnfg_monitors
Bit 6
los_flag_on_
TDO
FINAL
Description
Bit 5
Bit 4
ultra_fast_
switch
ext_switch
DATASHEET
(R/W) Configuration register
Default Value
controlling several input
monitoring and switching options.
Bit 3
PBO_freeze
Description
Bit Value
Bit 2
PBO_en
0000 0101*
Bit 1
freq_monitor_
soft_enable
Bit 0
freq_monitor_
hard_enable
Value Description
4
ext_switch
Bit to enable external switching mode. When in
external switching mode, the device is only allowed
to lock to a pair of sources. If the programmed
priority of input I3 is non-zero, then the SRCSW pin
is High, the device will be forced to lock to input I3
regardless of the signal present on that input. If the
programmed priority of input I3 is zero, then it will
be forced to lock to input I5 instead. If the
programmed priority of input I4 is non-zero, then the
SRCSW pin is Low, the device will be forced to lock
to input I4 regardless of the signal present on that
input. If the programmed priority of input I4 is zero,
then it will be forced to lock to input I6 instead.
* The default value of this bit is dependent on the
value of the SRCSWIT pin at power-up.
0
1
Normal operation mode.
External source switching mode enabled. Operating
mode of the device is always forced to be “locked”
when in this mode.
3
PBO_freeze
Bit to control the freezing of Phase Build-out
operation. If Phase Build-out has been enabled and
there have been some source switches, then the
input-output phase relationship of the T0 DPLL is
unknown. If Phase Build-out is no longer required,
then it can be frozen. This will maintain the current
input-output phase relationship, but not allow
further Phase Build-out events to take place. Simply
disabling Phase Build-out could cause a phase shift
in the output, as the T0 DPLL re-locks the phase to
zero degrees.
0
1
Phase Build-out not frozen.
Phase Build-out frozen, no further Phase Build-out
events will occur.
2
PBO_en
Bit to enable Phase Build-out events on source
switching. When enabled a Phase Build-out event is
triggered every time the T0 DPLL selects a new
source- this includes exiting the Holdover or Freerun states.
0
1
Phase Build-out not enabled. T0 DPLL locks to zero
degrees phase.
Phase Build-out enabled on source switching.
1
freq_monitor_soft_enable
Control to enable frequency monitoring of input
reference sources using soft frequency alarms.
0
1
Soft frequency monitor alarms disabled.
Soft frequency monitor alarms enabled.
0
freq_monitor_hard_enable
Control to enable frequency monitoring of input
reference sources using hard frequency alarms.
0
1
Hard frequency monitor alarms disabled.
Hard frequency monitor alarms enabled.
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Address (hex): 49
Register Name
cnfg_freq_mon_threshold
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to set both the
hard and soft frequency alarm
limits for the monitors on the
input reference sources.
Bit 4
Bit 3
soft_frequency_alarm_threshold
Bit No.
Default Value
Bit 2
0010 0011
Bit 1
Bit 0
hard_frequency_alarm_threshold
Description
Bit Value
[7:4]
soft_frequency_alarm_threshold
Threshold to trigger the soft frequency alarms in the
sts_reference_sources registers.
This is only used for monitoring.
[3:0]
hard_frequency_alarm_threshold
Threshold to trigger the hard frequency alarms in
the sts_reference_sources registers, which can
cause a reference source rejection.
-
Value Description
To calculate the limit in ppm, add one to the 4-bit
value in the register, and multiply by 3.81 ppm. The
limit is symmetrical about zero. A value of 0010 bin
corresponds to an alarm limit of ±11.43 ppm.
To calculate the limit in ppm, add one to the 4-bit
value in the register, and multiply by 3.81 ppm. The
limit is symmetrical about zero. A value of 0011 bin
corresponds to an alarm limit of ±15.24 ppm.
Address (hex): 4A
Register Name
Bit 7
cnfg_current_freq_mon_
threshold
Bit 6
Description
Bit 5
(R/W) Register to set both the
hard and soft frequency alarm
limits for the monitors on the
currently selected reference
source.
Bit 4
Bit 3
current_soft_frequency_alarm_threshold
Bit No.
Bit 2
0010 0011
Bit 1
Bit 0
current_hard_frequency_alarm_threshold
Description
Bit Value
[7:4]
current_soft_frequency_alarm_threshold
Threshold to trigger the soft frequency alarm in the
sts_reference_sources register applying to the
currently selected source.The currently selected
source can be monitored for frequency using
different limits to all other sources.
[3:0]
current_hard_frequency_alarm_threshold
Threshold to trigger the hard frequency alarm in the
sts_reference_sources register applying to the
currently selected source.
Revision 3.02/October 2005 © Semtech Corp.
Default Value
Page 98
-
Value Description
To calculate the limit in ppm, add one to the 4-bit
value in the register, and multiply by 3.81 ppm. The
limit is symmetrical about zero. A value of 0010 bin
corresponds to an alarm limit of ±11.43 ppm.
To calculate the limit in ppm, add one to the 4-bit
value in the register, and multiply by 3.81 ppm. The
limit is symmetrical about zero. A value of 0011 bin
corresponds to an alarm limit of ±15.24 ppm.
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Address (hex): 4B
Register Name
Bit 7
cnfg_registers_source_select
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to select the
source of many of the registers.
Bit 4
Bit 3
T4_T0_select
Bit No.
[7:5]
4
[3:0]
Description
Default Value
Bit 2
Bit 1
Value Description
Not used.
-
-
T4_T0_select
Bit to select between the T0 and T4 path for:
Reg. 0A, 0B (sts_priority_table)
Reg. 0C, 0D and 07 (sts_current_DPLL_frequency)
Reg. 18 to 1E (cnfg_ref_selection_priority)
Reg. 77, 78 (sts_current_phase)
0
1
T0 path registers selected.
T4 path registers selected.
Revision 3.02/October 2005 © Semtech Corp.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Page 99
Bit 0
frequency_measurement_channel_select
Bit Value
frequency_measurement_channel_select
Register to select which input channel the
frequency measurement result in Reg. 4C
(sts_freq_measurement) is taken from.
0000 0000
Not used- refers to no input channel.
Frequency measurement taken from input I1.
Frequency measurement taken from input I2.
Frequency measurement taken from input I3.
Frequency measurement taken from input I4.
Frequency measurement taken from input I5.
Frequency measurement taken from input I6.
Frequency measurement taken from input I7.
Frequency measurement taken from input I8.
Frequency measurement taken from input I9.
Frequency measurement taken from input I10.
Frequency measurement taken from input I11.
Frequency measurement taken from input I12.
Frequency measurement taken from input I13.
Frequency measurement taken from input I14.
Not used- refers to no input channel.
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Address (hex): 4C
Register Name
sts_freq_measurement
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register from which the
frequency measurement result
can be read.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
freq_measurement_value
Bit No.
[7:0]
Description
Bit Value
freq_measurement_value
This represents the value of the frequency
measurement on the channel number selected in
Reg. 4B (cnfg_registers_source_select). This value
will represent the offset in frequency from the clock
to the frequency monitors. This can be either the
crystal oscillator to the device, or the output of the
T0 DPLL as selected in Bit 7 (freq_mon_clk) of
Reg. 48 cnfg_monitors.
-
Value Description
This is an 8-bit 2’s complement signed integer. To
calculate the offset in ppm of the selected input
channel, this value should be multiplied by
3.81 ppm.
Address (hex): 4D
Register Name
Bit 7
cnfg_DPLL_soft_limit
Bit 6
Description
Bit 5
freq_lim_ph_
loss
Bit No.
(R/W) Register to program the
Default Value
soft frequency limit of the two
DPLLs. Exceeding this limit will
have no effect beyond triggering a
flag.
Bit 4
Bit 3
Bit 2
Bit 1
1000 1110
Bit 0
DPLL_soft_limit_value
Description
Bit Value
Value Description
7
freq_lim_ph_loss
Bit to enable the phase lost indication when the
DPLL hits its hard frequency limit as programmed in
Reg. 41 and Reg. 42 (cnfg_DPLL_freq_limit). This
results in the DPLL entering the phase lost state any
time the DPLL tracks to the extent of its hard limit.
0
1
Phase lost/locked determined normally.
Phase lost forced when DPLL tracks to hard limit.
[6:0]
DPLL_soft_limit_value
Register to program to what extent either of the
DPLLs tracks a source before raising its soft
frequency alarm flag (Bits 5 and 4 of Reg. 09,
sts_operating). This offset is compared to the
crystal oscillator frequency taking into account any
programmed calibration.
-
To calculate the ppm offset multiply this 7-bit value
by 0.628 ppm. The limit is symmetrical about zero.
A value of 0001110 bin is equivalent to ±8.79 ppm.
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Address (hex): 50
Register Name
cnfg_upper_threshold_0
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to program the
activity alarm setting limit for
Leaky Bucket Configuration 0.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0110
Bit 0
upper_threshold_0_value
Bit No.
[7:0]
Description
Bit Value
upper_threshold_0_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 53 (cnfg_decay_rate_0), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will raise an
inactivity alarm.
When the accumulator count reaches the value
programmed as the upper_threshold_0_value, the
Leaky Bucket raises an input inactivity alarm.
Address (hex): 51
Register Name
Bit 7
cnfg_lower_threshold_0
Bit 6
Bit 5
Description
(R/W) Register to program the
activity alarm resetting limit for
Leaky Bucket Configuration 0.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0100
Bit 0
lower_threshold_0_value
Bit No.
[7:0]
Description
Bit Value
lower_threshold_0_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 53 (cnfg_decay_rate_0), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will reset an
inactivity alarm.
The lower_threshold_0_value is the value at which
the Leaky Bucket will reset an inactivity alarm.
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Address (hex): 52
Register Name
cnfg_bucket_size_0
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to program the
maximum size limit for Leaky
Bucket Configuration 0.
Bit 4
Bit 3
Default Value
Bit 2
0000 1000
Bit 1
Bit 0
bucket_size_0_value
Bit No.
[7:0]
Description
Bit Value
bucket_size_0_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 53 (cnfg_decay_rate_0), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will stop
incrementing, even with further inactive periods.
The number in the Bucket cannot exceed the value
programmed into this register.
Address (hex): 53
Register Name
Bit 7
cnfg_decay_rate_0
Bit 6
Description
Bit 5
(R/W) Register to program the
“decay” or “leak” rate for Leaky
Bucket Configuration 0.
Bit 4
Bit 3
Default Value
Bit 2
0000 0001
Bit 1
Bit 0
decay_rate_0_value
Bit No.
Description
Bit Value
[7:2]
Not used.
-
[1:0]
decay_rate_0_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in this register, in which this does not
occur, the accumulator is decremented by 1.
00
01
10
11
Value Description
Bucket decay rate of 1 every 128 ms.
Bucket decay rate of 1 every 256 ms.
Bucket decay rate of 1 every 512 ms.
Bucket decay rate of 1 every 1024 ms.
The Leaky Bucket can be programmed to “leak” or
“decay” at the same rate as the “fill” cycle, or
effectively at one half, one quarter, or one eighth of
the fill rate.
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Address (hex): 54
Register Name
cnfg_upper_threshold_1
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to program the
activity alarm setting limit for
Leaky Bucket Configuration 1.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0110
Bit 0
upper_threshold_1_value
Bit No.
[7:0]
Description
Bit Value
upper_threshold_1_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 57 (cnfg_decay_rate_1), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will raise an
inactivity alarm.
When the accumulator count reaches the value
programmed as the upper_threshold_1_value, the
Leaky Bucket raises an input inactivity alarm.
Address (hex): 55
Register Name
Bit 7
cnfg_lower_threshold_1
Bit 6
Bit 5
Description
(R/W) Register to program the
activity alarm resetting limit for
Leaky Bucket Configuration 1.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0100
Bit 0
lower_threshold_1_value
Bit No.
[7:0]
Description
Bit Value
lower_threshold_1_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 57 (cnfg_decay_rate_1), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will reset an
inactivity alarm.
The lower_threshold_1_value is the value at which
the Leaky Bucket will reset an inactivity alarm.
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Address (hex): 56
Register Name
cnfg_bucket_size_1
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to program the
maximum size limit for Leaky
Bucket Configuration 1.
Bit 4
Bit 3
Default Value
Bit 2
0000 1000
Bit 1
Bit 0
bucket_size_1_value
Bit No.
[7:0]
Description
Bit Value
bucket_size_1_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 57 (cnfg_decay_rate_1), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will stop
incrementing, even with further inactive periods.
The number in the Bucket cannot exceed the value
programmed into this register.
Address (hex): 57
Register Name
Bit 7
cnfg_decay_rate_1
Bit 6
Description
Bit 5
(R/W) Register to program the
“decay” or “leak” rate for Leaky
Bucket Configuration 1.
Bit 4
Bit 3
Default Value
Bit 2
0000 0001
Bit 1
Bit 0
decay_rate_1_value
Bit No.
Description
Bit Value
[7:2]
Not used.
-
[1:0]
decay_rate_1_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in this register, in which this does not
occur, the accumulator is decremented by 1.
00
01
10
11
Value Description
Bucket decay rate of 1 every 128 ms.
Bucket decay rate of 1 every 256 ms.
Bucket decay rate of 1 every 512 ms.
Bucket decay rate of 1 every 1024 ms.
The Leaky Bucket can be programmed to “leak” or
“decay” at the same rate as the “fill” cycle, or
effectively at one half, one quarter, or one eighth of
the fill rate.
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Address (hex): 58
Register Name
cnfg_upper_threshold_2
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to program the
activity alarm setting limit for
Leaky Bucket Configuration 2.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0110
Bit 0
upper_threshold_2_value
Bit No.
[7:0]
Description
Bit Value
upper_threshold_2_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 5B (cnfg_decay_rate_2), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will raise an
inactivity alarm.
When the accumulator count reaches the value
programmed as the upper_threshold_2_value, the
Leaky Bucket raises an input inactivity alarm.
Address (hex): 59
Register Name
Bit 7
cnfg_lower_threshold_2
Bit 6
Bit 5
Description
(R/W) Register to program the
activity alarm resetting limit for
Leaky Bucket Configuration 2.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0100
Bit 0
lower_threshold_2_value
Bit No.
[7:0]
Description
Bit Value
lower_threshold_2_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 5B (cnfg_decay_rate_2), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will reset an
inactivity alarm.
The lower_threshold_2_value is the value at which
the Leaky Bucket will reset an inactivity alarm.
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Address (hex): 5A
Register Name
cnfg_bucket_size_2
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to program the
maximum size limit for Leaky
Bucket Configuration 2.
Bit 4
Bit 3
Default Value
Bit 2
0000 1000
Bit 1
Bit 0
bucket_size_2_value
Bit No.
[7:0]
Description
Bit Value
bucket_size_2_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 5B (cnfg_decay_rate_2), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will stop
incrementing, even with further inactive periods.
The number in the Bucket cannot exceed the value
programmed into this register.
Address (hex): 5B
Register Name
Bit 7
cnfg_decay_rate_2
Bit 6
Description
Bit 5
(R/W) Register to program the
“decay” or “leak” rate for Leaky
Bucket Configuration 2.
Bit 4
Bit 3
Default Value
Bit 2
0000 0001
Bit 1
Bit 0
decay_rate_2_value
Bit No.
Description
Bit Value
[7:2]
Not used.
-
[1:0]
decay_rate_2_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in this register, in which this does not
occur, the accumulator is decremented by 1.
00
01
10
11
Value Description
Bucket decay rate of 1 every 128 ms.
Bucket decay rate of 1 every 256 ms.
Bucket decay rate of 1 every 512 ms.
Bucket decay rate of 1 every 1024 ms.
The Leaky Bucket can be programmed to “leak” or
“decay” at the same rate as the “fill” cycle, or
effectively at one half, one quarter, or one eighth of
the fill rate.
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Address (hex): 5C
Register Name
cnfg_upper_threshold_3
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to program the
activity alarm setting limit for
Leaky Bucket Configuration 3.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0110
Bit 0
upper_threshold_3_value
Bit No.
[7:0]
Description
Bit Value
upper_threshold_3_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 5F (cnfg_decay_rate_3), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will raise an
inactivity alarm.
When the accumulator count reaches the value
programmed as the upper_threshold_3_value, the
Leaky Bucket raises an input inactivity alarm.
Address (hex): 5D
Register Name
Bit 7
cnfg_lower_threshold_3
Bit 6
Bit 5
Description
(R/W) Register to program the
activity alarm resetting limit for
Leaky Bucket Configuration 3.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0100
Bit 0
lower_threshold_3_value
Bit No.
[7:0]
Description
Bit Value
lower_threshold_3_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 5F (cnfg_decay_rate_3), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will reset an
inactivity alarm.
The lower_threshold_3_value is the value at which
the Leaky Bucket will reset an inactivity alarm.
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Address (hex): 5E
Register Name
cnfg_bucket_size_3
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to program the
maximum size limit for Leaky
Bucket Configuration 3.
Bit 4
Bit 3
Default Value
Bit 2
0000 1000
Bit 1
Bit 0
bucket_size_3_value
Bit No.
[7:0]
Description
Bit Value
bucket_size_3_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in Reg. 5F (cnfg_decay_rate_3), in
which this does not occur, the accumulator is
decremented by 1.
-
Value Description
Value at which the Leaky Bucket will stop
incrementing, even with further inactive periods.
The number in the Bucket cannot exceed the value
programmed into this register.
Address (hex): 5F
Register Name
Bit 7
cnfg_decay_rate_3
Bit 6
Description
Bit 5
(R/W) Register to program the
“decay” or “leak” rate for Leaky
Bucket Configuration 3.
Bit 4
Bit 3
Default Value
Bit 2
0000 0001
Bit 1
Bit 0
decay_rate_3_value
Bit No.
Description
Bit Value
[7:2]
Not used.
-
[1:0]
decay_rate_3_value
The Leaky Bucket operates on a 128 ms cycle. If,
during a cycle, it detects that an input has either
failed or has been erratic, then for each cycle in
which this occurs, the accumulator is incremented
by 1, and for each period of 1, 2, 4, or 8 cycles, as
programmed in this register, in which this does not
occur, the accumulator is decremented by 1.
Value Description
-
00
01
10
11
Bucket decay rate of 1 every 128 ms.
Bucket decay rate of 1 every 256 ms.
Bucket decay rate of 1 every 512 ms.
Bucket decay rate of 1 every 1024 ms.
The Leaky Bucket can be programmed to “leak” or
“decay” at the same rate as the “fill” cycle, or
effectively at one half, one quarter, or one eighth of
the fill rate.
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Address (hex): 60
Register Name
Bit 7
cnfg_output_frequency
(TO1 & TO2)
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure and
enable the frequencies available
on outputs TO1 and TO2.
Bit 4
Bit 3
output_freq_2
Bit No.
Default Value
Bit 2
Bit 1
1000 0101
Bit 0
output_freq_1
Description
Bit Value
Value Description
[7:4]
output_freq_2
Configuration of the output frequency available at
output TO2. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
Digital2 (Reg. 39 cnfg_digital_frequencies).
Digital1 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency/48.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/64.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
[3:0]
output_freq_1
Configuration of the output frequency available at
output TO1. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
Digital2 (Reg. 39 cnfg_digital_frequencies).
Digital1 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency/48.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/64.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
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Address (hex): 61
Register Name
Bit 7
cnfg_output_frequency
(TO3 & TO4)
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure and
enable the frequencies available
on outputs TO3 and TO4.
Bit 4
Bit 3
output_freq_4
Bit No.
Default Value
Bit 2
Bit 1
1000 0110
Bit 0
output_freq_3
Description
Bit Value
Value Description
[7:4]
output_freq_4
Configuration of the output frequency available at
output TO4. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
Digital2 (Reg. 39 cnfg_digital_frequencies).
Digital1 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency/48.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/2.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
[3:0]
output_freq_3
Configuration of the output frequency available at
output TO3. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
Digital2 (Reg. 39 cnfg_digital_frequencies).
Digital1 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency/48.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/64.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
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Address (hex): 62
Register Name
Bit 7
cnfg_output_frequency
(TO5 & TO6)
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure and
enable the frequencies available
on outputs TO5 and TO6.
Bit 4
Bit 3
output_freq_6
Bit No.
Default Value
Bit 2
Bit 1
1000 1010
Bit 0
output_freq_5
Description
Bit Value
Value Description
[7:4]
output_freq_6
Configuration of the output frequency available at
output TO6. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
T0 APLL frequency/2.
Digital1 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/64.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
[3:0]
output_freq_5
Configuration of the output frequency available at
output TO5. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
Digital2 (Reg. 39 cnfg_digital_frequencies).
Digital1 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency/48.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/2.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
Revision 3.02/October 2005 © Semtech Corp.
Page 111
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Address (hex): 63
Register Name
Bit 7
MFrSync_en
Bit No.
cnfg_output_frequency
(TO7 to TO11)
Bit 6
FrSync_en
FINAL
Description
Bit 5
TO9_en
DATASHEET
(R/W) Register to configure and
enable the frequencies available
on outputs TO7 through to TO11.
Bit 4
Bit 3
TO8_en
Default Value
Bit 2
Description
Bit Value
Value Description
MFrSync_en
Register bit to enable the 2 kHz Sync output (TO11).
0
1
Output TO11 disabled.
Output TO11 enabled.
6
FrSync_en
Register bit to enable the 8 kHz Sync output (TO10).
0
1
Output TO10 disabled.
Output TO10 enabled.
5
TO9_en
Register bit to enable the BITS output from the TO9.
0
1
Output TO9 disabled.
Output TO9 enabled.
4
TO8_en
Register bit to enable the AMI composite clock
output from TO8.
0
1
Output TO8 disabled.
Output TO8 enabled.
output_freq_7
Configuration of the output frequency available at
output TO7. Many of the frequencies available are
dependent on the frequencies of the T0 APLL and
the T4 APLL. These are configured in Reg. 64 and
Reg. 65. For more detail see the detailed section on
configuring the output frequencies.
Revision 3.02/October 2005 © Semtech Corp.
Bit 0
output_freq_7
7
[3:0]
Bit 1
1111 0110
Page 112
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Output disabled.
2 kHz.
8 kHz.
Digital2 (Reg. 39 cnfg_digital_frequencies).
T0 APLL frequency/2.
T0 APLL frequency/48.
T0 APLL frequency/16.
T0 APLL frequency/12.
T0 APLL frequency/8.
T0 APLL frequency/6.
T0 APLL frequency/4.
T4 APLL frequency/64.
T4 APLL frequency/48.
T4 APLL frequency/16.
T4 APLL frequency/8.
T4 APLL frequency/4.
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Address (hex): 64
Register Name
Bit 7
cnfg_T4_DPLL_frequency
Bit 6
Auto_squelch_
T4
Bit No.
Bit 5
AMI_op_duty
FINAL
Description
DATASHEET
(R/W) Register to configure the T4 Default Value
DPLL and several other
parameters for the T4 path.
Bit 4
Bit 3
Bit 2
T4_op_
SONSDH
0000 0001
Bit 1
Bit 0
T4_DPLL_frequency
Description
Bit Value
Value Description
7
Not used.
-
-
6
Auto_squelch_T4
Register bit to automatically squelch the T4 outputs
on TO8 and TO9 when the T4 inputs have failed.
0
1
Outputs TO8 and TO9 enabled as in Reg. 63.
Outputs TO8 and TO9 disabled when T4 inputs fail.
5
AMI_op_duty
Register bit to configure whether the composite
clock output of TO8 is 50:50 or 5:8 duty cycle.
0
1
TO8 output 50:50 duty cycle.
TO8 output 5:8 duty cycle.
4
T4_op_SONSDH
Register bit to configure the BITS output on TO9 to
be either SONET or SDH frequency, only when
Reg. 35 Bit 4 = 0, otherwise this bit is ignored and
SONET/SDH selection for TO9 is controlled by
Reg. 34 Bit 2.
Default set by SONSDHB pin - same as Reg. 34 Bit
2.
0
1
TO9 output 2.048 MHz (SDH).
TO9 output 1.544 MHz (SONET).
3
Not used.
-
-
[2:0]
T4_DPLL_frequency
Register to configure the frequency of operation of
the DPLL in the T4 path. The frequency of the DPLL
will also affect the frequency of the T4 APLL which,
in turn, affects the frequencies available at outputs
TO1 - TO7 see Reg. 60 - Reg. 63. It is also possible
to not use the T4 DPLL at all, but use the T4 APLL to
run directly from the T0 DPLL output, see Reg. 65
(cnfg_TO_DPLL_frequency). If any frequencies are
required from the T4 APLL then the T4 DPLL should
not be squelched, as the T4 APLL input is squelched
and the T4 APLL will free run.
000
001
010
011
100
101
110
111
Revision 3.02/October 2005 © Semtech Corp.
Page 113
T4 DPLL mode = squelched (clock off).
T4 DPLL mode = 77.76 MHz (OC-N rates), giving
T4 APLL output frequency (before dividers) =
311.04 MHz.
T4 DPLL mode = 12E1, giving T4 APLL output
frequency (before dividers) = 98.304 MHz.
T4 DPLL mode = 16E1, giving T4 APLL output
frequency (before dividers) = 131.072 MHz.
T4 DPLL mode = 24DS1, giving T4 APLL output
frequency (before dividers) = 148.224 MHz.
T4 DPLL mode = 16DS1, giving T4 APLL output
frequency (before dividers) = 98.816 MHz.
T4 DPLL mode = E3, giving T4 APLL output
frequency (before dividers) = 274.944 MHz.
T4 DPLL mode = DS3, giving T4 APLL output
frequency (before dividers) = 178.944 MHz.
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Address (hex): 65
Register Name
Bit 7
T4_meas_T0_
ph
Bit No.
cnfg_T0_DPLL_frequency
Bit 6
T4_APLL_for_
T0
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure the T0 Default Value
DPLL and several other
parameters for the T0 path.
Bit 4
Bit 3
Bit 2
0000 0001
Bit 1
Bit 0
T0_DPLL_frequency
T0_freq_to_T4_APLL
Description
Bit Value
Value Description
7
T4_meas_T0_ph
Register bit to control the feature to use the T4 path
to measure phase offset from the T0 path. When
enabled the T4 path is disabled and the phase
detector is used to measure the phase between the
input to the T0 DPLL and the selected T4 input.
0
1
Normal- T4 Path normal operation.
T4 DPLL disabled, T4 phase detector used to
measure phase between selected T0 input and
selected T4 input.
6
T4_APLL_for_T0
Register bit to select whether the T4 APLL takes its
input from the T4 DPLL or the T0 DPLL. If the T0
DPLL is selected then the frequency is controlled by
Bits [5:4], T0_freq_to_T4_APLL.
0
1
T4 APLL takes its input from the T4 DPLL.
T4 APLL takes its input from the T0 DPLL.
[5:4]
T0_freq_to_T4_APLL
Register to select the T0 frequency driven to the T4
APLL (T0 DPLL mode*) when selected by Bit 6,
T4_APLL_for_T0; and consequently the APLL output
frequency in the T4 path.
*Note that this is not the operating frequency of the
T0 DPLL itself - which is fixed at outputting
77.76 MHz - but is the multiplied output from the LF
Output DFS block. See “PLL Block Diagram” on
page 33.
00
T0 DPLL mode = 12E1, giving T4 APLL output
frequency (before dividers) = 98.304 MHz.
T0 DPLL mode = 16E1, giving T4 APLL output
frequency (before dividers) = 131.072 MHz.
T0 DPLL mode = 24DS1, giving T4 APLL output
frequency (before dividers) = 148.224 MHz.
T0 DPLL mode = 16DS1, giving T4 APLL output
frequency (before dividers) = 98.816 MHz.
3
[2:0]
Not used.
01
10
11
-
T0_DPLL_frequency
Register to configure the frequency driven to the T0
APLL (T0 DPLL mode*) and consequently the APLL
output frequency in the T0 path. This register
affects the frequencies available at TO1 - TO7 see
Reg. 60 - Reg. 63.
*Note that this is not the operating frequency of the
T0 DPLL itself - which is fixed at outputting
77.76 MHz - but is the multiplied output from the LF
Output DFS block. See “PLL Block Diagram” on
page 33.
000
001
010
011
100
101
110
111
Revision 3.02/October 2005 © Semtech Corp.
Page 114
T0 DPLL mode = 77.76 MHz, digital feedback,
T0 APLL output frequency (before dividers) =
311.04 MHz.
T0 DPLL mode = 77.76 MHz, analog feedback,
T0 APLL output frequency (before dividers) =
311.04 MHz.
T0 DPLL mode = 12E1, giving T0 APLL output
frequency (before dividers) = 98.304 MHz.
T0 DPLL mode = 16E1, giving T0 APLL output
frequency (before dividers) = 131.072 MHz.
T0 DPLL mode = 24DS1, giving T0 APLL output
frequency (before dividers) = 148.224 MHz.
T0 DPLL mode = 16DS1, giving T0 APLL output
frequency (before dividers) = 98.816 MHz.
Not used.
Not used.
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Address (hex): 66
Register Name
cnfg_T4_DPLL_bw
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure the
bandwidth of the T4 DPLL.
Bit 4
Bit 3
Default Value
Bit 2
0000 0000
Bit 1
Bit 0
T4_DPLL_bandwidth
Bit No.
Description
Bit Value
[7:2]
Not used.
-
[1:0]
T4_DPLL_bandwidth
Register to configure the bandwidth of the T4 DPLL.
00
01
10
11
Value Description
T4 DPLL 18 Hz bandwidth.
T4 DPLL 35 Hz bandwidth.
T4 DPLL 70 Hz bandwidth.
Not used.
Address (hex): 67
Register Name
Bit 7
cnfg_T0_DPLL_locked_bw
Bit 6
Bit 5
Description
(R/W) Register to configure the
bandwidth of the T0 DPLL, when
phase locked to an input.
Bit 4
Bit 3
Default Value
Bit 2
0000 1011
Bit 1
Bit 0
T0_DPLL_locked_bandwidth
Bit No.
Description
Bit Value
[7:4]
Not used.
[3:0]
T0_DPLL_locked_bandwidth
Register to configure the bandwidth of the T0 DPLL
when locked to an input reference. Reg. 3B Bit 7 is
used to control whether this bandwidth is used all of
the time or automatically switched to when phase
locked.
Revision 3.02/October 2005 © Semtech Corp.
1000
1001
1010
1011
1100
1101
1110
1111
0000
0001
All other values
Page 115
Value Description
T0 DPLL 0.1 Hz locked bandwidth.
T0 DPLL 0.3 Hz locked bandwidth.
T0 DPLL 0.6 Hz locked bandwidth.
T0 DPLL 1.2 Hz locked bandwidth.
T0 DPLL 2.5 Hz locked bandwidth.
T0 DPLL 4 Hz locked bandwidth.
T0 DPLL 8 Hz locked bandwidth.
T0 DPLL 18 Hz locked bandwidth.
T0 DPLL 35 Hz locked bandwidth.
T0 DPLL 70 Hz locked bandwidth.
Not used.
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Address (hex): 69
Register Name
cnfg_T0_DPLL_acq_bw
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure the
bandwidth of the T0 DPLL, when
not phase locked to an input.
Bit 4
Bit 3
Default Value
Bit 2
0000 1111
Bit 1
Bit 0
T0_DPLL_acquisition_bandwidth
Bit No.
Description
Bit Value
[7:4]
Not used.
-
[3:0]
T0_DPLL_acquisition_bandwidth
Register to configure the bandwidth of the T0 DPLL
when acquiring phase lock on an input reference.
Reg. 3B Bit 7 is used to control whether this
bandwidth is not used or automatically switched to
when not phase locked.
1000
1001
1010
1011
1100
1101
1110
1111
0000
0001
All other values
Value Description
T0 DPLL 0.1 Hz acquisition bandwidth.
T0 DPLL 0.3 Hz acquisition bandwidth.
T0 DPLL 0.6 Hz acquisition bandwidth.
T0 DPLL 1.2 Hz acquisition bandwidth.
T0 DPLL 2.5 Hz acquisition bandwidth.
T0 DPLL 4 Hz acquisition bandwidth.
T0 DPLL 8 Hz acquisition bandwidth.
T0 DPLL 18 Hz acquisition bandwidth.
T0 DPLL 35 Hz acquisition bandwidth.
T0 DPLL 70 Hz acquisition bandwidth.
Not used.
Address (hex): 6A
Register Name
Bit 7
cnfg_T4_DPLL_damping
Bit 6
Description
Bit 5
(R/W) Register to configure the
damping factor of the T4 DPLL,
along with the gain of Phase
Detector 2 in some modes.
Bit 4
Bit 3
Default Value
Bit 2
T4_PD2_gain_alog_8k
Bit No.
7
[6:4]
3
Bit 1
0001 0011
Bit 0
T4_damping
Description
Bit Value
Value Description
Not used.
-
-
T4_PD2_gain_alog_8k
Register to control the gain of the Phase Detector 2
when locking to a reference of 8 kHz or less in
analog feedback mode. This setting is only used if
automatic gain selection is enabled in Reg. 6C Bit 7,
cnfg_T4_DPLL_PD2_gain.
-
Gain value of the Phase Detector 2 when locking to
an 8 kHz reference in analog feedback mode.
Not used.
-
-
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Address (hex): 6A (cont...)
Register Name
cnfg_T4_DPLL_damping
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure the
damping factor of the T4 DPLL,
along with the gain of Phase
Detector 2 in some modes.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
T4_PD2_gain_alog_8k
Bit No.
[2:0]
Bit Value
T4_damping
Register to configure the damping factor of the T4
DPLL. The bit values corresponds to different
damping factors, depending on the bandwidth
selected. Damping factor of 5 being the default
(011).
The Gain Peak for the Damping Factors given in the
Value Description (right) are tabulated below.
Gain Peak
1.2
2.5
5
10
20
Bit 0
T4_damping
Description
Damping Factor
0001 0011
0.4 dB
0.2 dB
0.1 dB
0.06 dB
0.03 dB
Value Description
001
010
011
100
101
T4 DPLL damping factor at the following bandwidths
frequency selections:
18 Hz
35 Hz
70 Hz
1.2
1.2
1.2
2.5
2.5
2.5
5
5
5
5
10
10
5
10
20
000
110
111
Not used.
Not used.
Not used.
Address (hex): 6B
Register Name
Bit 7
cnfg_T0_DPLL_damping
Bit 6
Description
Bit 5
(R/W) Register to configure the
damping factor of the T0 DPLL,
along with the gain of the Phase
Detector 2 in some modes.
Bit 4
Bit 3
Default Value
Bit 2
T0_PD2_gain_alog_8k
Bit No.
7
[6:4]
3
Bit 1
0001 0011
Bit 0
T0_damping
Description
Bit Value
Value Description
Not used.
-
-
T0_PD2_gain_alog_8k
Register to control the gain of the Phase Detector 2
when locking to a reference of 8 kHz or less in
analog feedback mode. This setting is only used if
automatic gain selection is enabled in Reg. 6D Bit 7,
cnfg_T0_DPLL_PD2_gain.
-
Gain value of the Phase Detector 2 when locking to
an 8 kHz reference in analog feedback mode.
Not used.
-
-
Revision 3.02/October 2005 © Semtech Corp.
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Address (hex): 6B (cont...)
Register Name
cnfg_T0_DPLL_damping
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure the
damping factor of the T0 DPLL,
along with the gain of the Phase
Detector 2 in some modes.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
T0_PD2_gain_alog_8k
Bit No.
[2:0]
Bit Value
T0_damping
Register to configure the damping factor of the T0
DPLL. The bit values corresponds to different
damping factors, depending on the bandwidth
selected. Damping factor of 5 being the default
(011).
The Gain Peak for the Damping Factors given in the
Value Description (right) are tabulated below.
Gain Peak
1.2
2.5
5
10
20
Bit 0
T0_damping
Description
Damping Factor
0001 0011
0.4 dB
0.2 dB
0.1 dB
0.06 dB
0.03 dB
Value Description
001
010
011
100
101
T0 DPLL damping factor at the following bandwidths
frequency selections:
8 Hz
18 Hz
35 Hz
70 Hz
<4 Hz
5
2.5
1.2
1.2
1.2
5
5
2.5
2.5
2.5
5
5
5
5
5
5
5
5
10
10
5
5
5
10
20
000
110
111
Not used.
Not used.
Not used.
Address (hex): 6C
Register Name
Bit 7
cnfg_T4_DPLL_PD2_gain
Bit 6
T4_PD2_gain_
enable
Bit No.
7
Bit 5
Description
(R/W) Register to configure the
Default Value
gain of Phase Detector 2 in some
modes for the T4 DPLL.
Bit 4
Bit 3
Bit Value
T4_PD2_gain_enable
Revision 3.02/October 2005 © Semtech Corp.
Bit 1
Bit 0
T4_PD2_gain_digital
T4_PD2_gain_alog
Description
Bit 2
1100 0010
0
1
Page 118
Value Description
T4 DPLL Phase Detector 2 not used.
T4 DPLL Phase Detector 2 gain enabled and choice
of gain determined according to the locking mode:
- digital feedback mode
- analog feedback mode
- analog feedback at 8 kHz.
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Address (hex): 6C (cont...)
Register Name
cnfg_T4_DPLL_PD2_gain
Bit 7
Bit 6
T4_PD2_gain_
enable
Bit No.
[6:4]
3
[2:0]
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure the
Default Value
gain of Phase Detector 2 in some
modes for the T4 DPLL.
Bit 4
Bit 3
Bit 2
1100 0010
Bit 1
Bit 0
T4_PD2_gain_digital
T4_PD2_gain_alog
Description
Bit Value
Value Description
T4_PD2_gain_alog
Register to control the gain of Phase Detector 2
when locking to a reference, higher than 8 kHz, in
analog feedback mode. This setting is not used if
automatic gain selection is disabled in Bit 7,
T4_PD2_gain_enable.
-
Gain value of Phase Detector 2 when locking to a
high frequency reference in analog feedback mode.
Not used.
-
-
T4_PD2_gain_digital
Register to control the gain of Phase Detector 2
when locking to a reference in digital feedback
mode. This setting is always used if automatic gain
selection is disabled in Bit 7, T4_PD2_gain_enable.
-
Gain value of Phase Detector 2 when locking to any
reference in digital feedback mode.
Address (hex): 6D
Register Name
Bit 7
cnfg_T0_DPLL_PD2_gain
Bit 6
T0_PD2_gain_
enable
Bit No.
7
[6:4]
3
Bit 5
Description
(R/W) Register to configure the
Default Value
gain of Phase Detector 2 in some
modes for the T0 DPLL.
Bit 4
Bit 3
Bit 2
T0_PD2_gain_alog
1100 0010
Bit 1
Bit 0
T0_PD2_gain_digital
Description
Bit Value
Value Description
T0_PD2_gain_enable
0
1
T0 DPLL Phase Detector 2 not used.
T0 DPLL Phase Detector 2 gain enabled and choice
of gain determined according to the locking mode:
- digital feedback mode
- analog feedback mode
- analog feedback at 8 kHz.
T0_PD2_gain_alog
Register to control the gain of Phase Detector 2
when locking to a reference, higher than 8 kHz, in
analog feedback mode. This setting is not used if
automatic gain selection is disabled in Bit 7,
T0_PD2_gain_enable.
-
Gain value of Phase Detector 2 when locking to a
high frequency reference in analog feedback mode.
Not used.
-
-
Revision 3.02/October 2005 © Semtech Corp.
Page 119
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Address (hex): 6D (cont...)
Register Name
cnfg_T0_DPLL_PD2_gain
Bit 7
Bit 6
T0_PD2_gain_
enable
Bit No.
[2:0]
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure the
Default Value
gain of Phase Detector 2 in some
modes for the T0 DPLL.
Bit 4
Bit 3
Bit 2
1100 0010
Bit 1
Bit 0
T0_PD2_gain_digital
T0_PD2_gain_alog
Description
Bit Value
T0_PD2_gain_digital
Register to control the gain of Phase Detector 2
when locking to a reference in digital feedback
mode. This setting is always used if automatic gain
selection is disabled in Bit 7, T0_PD2_gain_enable.
-
Value Description
Gain value of Phase Detector 2 when locking to any
reference in digital feedback mode.
Address (hex): 70
Register Name
Bit 7
cnfg_phase_offset
[7:0]
Bit 6
Description
Bit 5
(R/W) Bits [7:0] of the phase
offset control register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
phase_offset_value[7:0]
Bit No.
[7:0]
Description
Bit Value
phase_offset_value[7:0]
Register forming part of the phase offset control.
Revision 3.02/October 2005 © Semtech Corp.
Page 120
-
Value Description
See Reg. 71, cnfg_phase_offset[15:8] for more
details.
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Address (hex): 71
Register Name
Bit 7
cnfg_phase_offset
[15:8]
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Bits [15:8] of the phase
offset control register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
phase_offset_value[15:8]
Bit No.
[7:0]
Description
Bit Value
phase_offset_value[15:8]
Register forming part of the phase offset control. If
the phase offset register is written to when the DPLL
is locked to an input, then it is possible that some
internal signals become out of synchronization. In
order to avoid this, the phase offset is automatically
“ramped” to the new value. If the phase offset is
only ever adjusted when the device is in Holdover,
then this is not necessary, and this automatic
“ramping” can be disabled, see Reg. 7C,
cnfg_sync_monitor.
This register is ignored and has no affect when
Phase Build-out is enabled in either Reg. 48 or
Reg. 76.
-
Value Description
The value in this register is to be concatenated with
the contents of Reg. 70 cnfg_phase_offset[7:0].
This value is a 16-bit 2’s complement signed
number. The value multiplied by 6.279 represents
the extent of the applied phase offset in
picoseconds.
The phase offset register is not a control to a
“traditional” delay line. This number 6.279 actually
represents a fractional portion of the period of an
internal 77.76 MHz cycle and can, therefore, be
represented more accurately as follows. Each bit
value of the register represents the period of the
internal 77.76 MHz clock divided by 211.
If, for example, the DPLL is locked to a reference
that is +1 ppm in frequency with respect to a perfect
oscillator, then the period, and hence the phase
offset, will be decreased by 1 ppm. Programming a
value of 1024 into the phase offset register will
produce a complete inversion of the 77.76 MHz
output clock.
Note...The exact period of the internal 77.76 MHz
clock is determined by the current state of the DPLL
i.e. in Locked mode its accuracy depends on that of
the locked to input, in Holdover or Free-run it
depends on the accuracy of the external oscillator.
Revision 3.02/October 2005 © Semtech Corp.
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Address (hex): 72
Register Name
cnfg_PBO_phase_offset
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to offset the mean Default Value
time error of Phase Build-out
events.
Bit 4
Bit 3
Bit 2
0000 0000
Bit 1
Bit 0
PBO_phase_offset
Bit No.
Description
Bit Value
Value Description
[7:6]
Not used.
-
-
[5:0]
PBO_phase_offset
Each time a Phase Build-out event is triggered,
there is an uncertainty of up to 5 ns introduced
which translates to a phase hit on the output. The
mean error over a large number of events is
designed to be zero. This register can be used to
introduce a fixed offset into each PBO event. This
will have the effect of moving the mean error
positive or negative in time.
-
The value in this register is a 6-bit 2’s complement
number. The value multiplied by 0.101 gives the
programmed offset in nanoseconds. Values greater
than +1.4 ns or less than -1.4 ns should NOT be
used as they may cause internal mathematical
errors.
Address (hex): 73
Register Name
Bit 7
fine_limit_en
Bit No.
cnfg_phase_loss_fine_limit
Bit 6
noact_ph_loss
Bit 5
Description
(R/W) Register to configure some Default Value
of the parameters of the T0 DPLL
phase detector.
Bit 4
Bit 3
Bit 2
1010 0010
Bit 1
Bit 0
phase_loss_fine_limit
narrow_en
Description
Bit Value
Value Description
7
fine_limit_en
Register bit to enable the phase_loss_fine_limit
Bits [2:0]. When disabled, phase lock/loss is
determined by the other means within the device.
This must be disabled when multi-UI jitter tolerance
is required, see Reg. 74,
cnfg_phase_loss_course_limit.
0
1
Phase loss indication only triggered by other means.
Phase loss triggered when phase error exceeds the
limit programmed in phase_loss_fine_limit,
Bits [2:0].
6
noact_ph_loss
The DPLL detects that an input has failed very
rapidly. Normally, when the DPLL detects this
condition, it does not consider phase lock to be lost
and will phase lock to the nearest edge (±180º)
when a source becomes available again, hence
giving tolerance to missing cycles. If phase loss is
indicated, then frequency and phase locking is
instigated (±360º locking). This bit can be used to
force the DPLL to indicate phase loss immediately
when no activity is detected.
0
No activity on reference does not trigger phase lost
indication.
No activity triggers phase lost indication.
Revision 3.02/October 2005 © Semtech Corp.
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Address (hex): 73 (cont...)
Register Name
cnfg_phase_loss_fine_limit
Bit 7
fine_limit_en
Bit No.
5
Bit 6
noact_ph_loss
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure some Default Value
of the parameters of the T0 DPLL
phase detector.
Bit 4
Bit 3
Bit 2
1010 0010
Bit 1
Bit 0
phase_loss_fine_limit
narrow_en
Description
Bit Value
Value Description
narrow_en (test control bit)
Set to 1 (default value)
0
1
Set to 1
[4:3]
Not used.
-
-
[2:0]
phase_loss_fine_limit
When enabled by Bit 7, this register coarsely sets
the phase limit at which the device indicates phase
lost or locked. The default value of 2 (010) gives a
window size of around ±(90º to 180º). The phase
position of the inputs to the DPLL has to be within
the window limit for 1 to 2 seconds before the
device indicates phase lock. If it is outside the
window for any time then phase loss is immediately
indicated. For most cases the default value of 2
(010) is satisfactory. The window size changes in
proportion to the value, so a value of 1 (001) will
give a narrow phase acceptance or lock window of
approximately ±(45º to 90º).
000
001
010
011
100
101
110
111
Do not use. Indicates phase loss continuously.
Small phase window for phase lock indication.
Recommended value.
)
)
) Larger phase window for phase lock indication.
)
)
Address (hex): 74
Register Name
Bit 7
coarse_limphaseloss_en
Bit No.
7
cnfg_phase_loss_coarse_limit
Bit 6
wide_range_en
Bit 5
Description
(R/W) Register to configure some Default Value
of the parameters of the T0 DPLL
phase detector.
Bit 4
Bit 3
multi_ph_resp
Bit 1
Bit 0
phase_loss_coarse_limit
Description
Bit Value
coarse_lim_phaseloss_en
Register bit to enable the coarse phase detector,
whose range is determined by
phase_loss_coarse_limit Bits [3:0]. This register
sets the limit in the number of input clock cycles (UI)
that the input phase can move by before the DPLL
indicates phase lost.
Revision 3.02/October 2005 © Semtech Corp.
Bit 2
1000 0101
Page 123
0
1
Value Description
Phase loss not triggered by the coarse phase lock
detector.
Phase loss triggered when phase error exceeds the
limit programmed in phase_loss_coarse_limit,
Bits [3:0].
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Address (hex): 74 (cont...)
Register Name
Bit 7
coarse_limphaseloss_en
Bit No.
cnfg_phase_loss_coarse_limit
Bit 6
wide_range_en
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure some Default Value
of the parameters of the T0 DPLL
phase detector.
Bit 4
Bit 3
Bit 2
Bit 1
1000 0101
Bit 0
phase_loss_coarse_limit
multi_ph_resp
Description
Bit Value
Value Description
6
wide_range_en
To enable the device to be tolerant to large amounts
of applied jitter and still do direct phase locking at
the input frequency rate (up to 77.76 MHz), a wide
range phase detector and phase lock detector is
employed. This bit enables the wide range phase
detector. This allows the device to be tolerant to,
and therefore keep track of, drifts in input phase of
many cycles (UI). The range of the phase detector
is set by the same register used for the phase loss
coarse limit (Bits [3:0]).
0
1
Wide range phase detector off.
Wide range phase detector on.
5
multi_ph_resp
Enables the phase result from the coarse phase
detector to be used in the DPLL algorithm. Bit 6
should also be set when this is activated. The
coarse phase detector can measure and keep track
over many thousands of input cycles, thus allowing
excellent jitter and wander tolerance. This bit
enables that phase result to be used in the DPLL
algorithm, so that a large phase measurement gives
a faster pull-in of the DPLL. If this bit is not set then
the phase measurement is limited to ±360º which
can give a slower pull-in rate at higher input
frequencies, but could also be used to give less
overshoot.
Setting this bit in direct locking mode, for example
with a 19.44 MHz input, would give the same
dynamic response as a 19.44 MHz input used with
8 k locking mode, where the input is divided down
internally to 8 kHz first.
0
DPLL phase detector limited to ±360º (±1 UI).
However it will still remember its original phase
position over many thousands of UI if Bit 6 is set.
1
DPLL phase detector also uses the full coarse
phase detector result. It can now measure up to:
±360º X 8191 UI = ±2,948,760º.
Not used.
-
-
4
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Address (hex): 74 (cont...)
Register Name
cnfg_phase_loss_coarse_limit
Bit 7
coarse_limphaseloss_en
Bit No.
[3:0]
Bit 6
wide_range_en
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure some Default Value
of the parameters of the T0 DPLL
phase detector.
Bit 4
Bit 3
Bit 2
1000 0101
Bit 1
Bit 0
phase_loss_coarse_limit
multi_ph_resp
Description
Bit Value
phase_loss_coarse_limit
Sets the range of the coarse phase loss detector
and the coarse phase detector.
When locking to a high frequency signal, and jitter
tolerance greater than 0.5 UI is required, then the
DPLL can be configured to track phase errors over
many input clock periods. This is particularly useful
with very low bandwidths. This register configures
how many UI over which the input phase can be
tracked. It also sets the range of the coarse phase
loss detector, which can be used with or without the
multi-UI phase capture range capability.
This register value is used by Bits 6 and 7.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100-1111
Value Description
Input phase error tracked over ±1 UI.
Input phase error tracked over ±3 UI.
Input phase error tracked over ±7 UI.
Input phase error tracked over ±15 UI.
Input phase error tracked over ±31 UI.
Input phase error tracked over ±63 UI.
Input phase error tracked over ±127 UI.
Input phase error tracked over ±255 UI.
Input phase error tracked over ±511 UI.
Input phase error tracked over ±1023 UI.
Input phase error tracked over ±2047 UI.
Input phase error tracked over ±4095 UI.
Input phase error tracked over ±8191 UI.
Address (hex): 76
Register Name
cnfg_phasemon
Bit 7
Bit 6
Description
Bit 5
(R/W) Register to configure the
noise rejection function for low
frequency inputs.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0110
Bit 0
ip_noise_
window
Bit No.
7
[6:0]
Description
Bit Value
Value Description
ip_noise_window
Register bit to enable a window of 5% tolerance
around low-frequency inputs (2, 4 and 8 kHz). This
feature ensures that any edge caused by noise
outside the 5% window where the edge is expected
will not be considered within the DPLL. This reduces
any possible phase hit when a low-frequency
connection is removed and contact bounce is
possible.
0
1
DPLL considers all edges for phase locking.
DPLL ignores input edges outside a 95% to 105%
window.
Not used.
-
-
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ACS8520 SETS
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Address (hex): 77
Register Name
sts_current_phase
[7:0]
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(RO) Bits [7:0] of the current
phase register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
current_phase[7:0]
Bit No.
[7:0]
Description
Bit Value
current_phase
Bits [7:0] of the current phase register. See Reg. 78
sts_current_phase [15:8] for details.
-
Value Description
See Reg. 78 sts_current_phase [15:8] for details.
Address (hex): 78
Register Name
sts_current_phase
[15:8]
Bit 7
Bit 6
Description
Bit 5
(RO) Bits [15:8] of the current
phase register.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
current_phase[15:8]
Bit No.
[7:0]
Description
Bit Value
current_phase
Bits [15:8] of the current phase register. This
register is used to read either from the phase
detector of either the T0 DPLL or the T4 DPLL,
according to Reg. 4B Bit 4 T4_T0_select. The value
is averaged in the phase averager before being
made available.
-
Value Description
The value in this register should be concatenated
with the value in Reg. 77 sts_current_phase [7:0].
This 16-bit value is a 2’s complement signed
integer. The value multiplied by 0.707 is the
averaged value of the current phase error, in
degrees, as measured at the DPLL’s phase
detector.
Address (hex): 79
Register Name
Bit 7
cnfg_phase_alarm_timeout
Bit 6
Bit 5
Description
(R/W) Register to configure how
long before a phase alarm is
raised on an input
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0011 0010
Bit 0
timeout_value
Bit No.
[7:6]
Description
Bit Value
Not used.
Revision 3.02/October 2005 © Semtech Corp.
-
Page 126
Value Description
-
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Address (hex): 79 (cont...)
Register Name
cnfg_phase_alarm_timeout
Bit 7
Bit 6
Bit 5
FINAL
Description
DATASHEET
(R/W) Register to configure how
long before a phase alarm is
raised on an input
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0011 0010
Bit 0
timeout_value
Bit No.
[5:0]
Description
Bit Value
timeout_value
Phase alarms can only be raised on an input when
the T0 DPLL is attempting to lock to it. Once an
input has been rejected due to a phase alarm, there
is no way to measure whether it is good again,
because it is no longer selected by the DPLL. The
phase alarms can either remain until reset by
software, or time-out after 128 second, as selected
in Reg. 34 Bit 6, phalarm_timeout
-
Value Description
This 6-bit unsigned integer represents the length of
time before a phase alarm will be raised on an
input. The value multiplied by 2 gives the time in
seconds. This time value is the time that the
controlling state machine will spend in Pre-locked,
Pre-locked2 or Phase-lost modes before setting the
phase alarm on the selected input.
Address (hex): 7A
Register Name
Bit 7
cnfg_sync_pulses
Bit 6
Description
Bit 5
(R/W) Register to configure the
Default Value
Sync outputs available from TO10
and TO11 and select the source
for the 2 kHz and 8 kHz outputs
from T01 - TO7.
Bit 4
Bit 3
8k_invert
2k_8k_from_T4
Bit No.
7
Description
Bit Value
Bit 2
8k_pulse
Bit 1
2k_invert
0
Not used.
-
-
3
8k_invert
Register bit to invert the 8 kHz output from TO10.
0
1
8 kHz TO10 output not inverted.
8 kHz TO10 output inverted.
2
8k_pulse
Register bit to enable the 8 kHz output from TO10
to be either pulsed or 50:50 duty cycle. Output TO3
must be enabled to use “pulsed output” mode on
output TO10, and then the pulse width on TO10 will
be defined by the period of the output programmed
on TO3.
0
1
8 kHz TO10 output not pulsed.
8 kHz TO10 output pulsed.
1
2k_invert
Register bit to invert the 2 kHz output from TO11.
0
1
2 kHz TO11 output not inverted.
2 kHz TO11 output inverted.
Revision 3.02/October 2005 © Semtech Corp.
Page 127
Bit 0
2k_pulse
Value Description
2k_8k_from_T4
Register to select the source (T0 or T4) for the 2 kHz
and 8 kHz outputs available from TO1 to TO7.
[6:4]
0000 0000
2/8 kHz on TO1-TO7 generated from the T0 DPLL.
2/8 kHz on TO1-TO7 generated from the T4 DPLL.
1
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Address (hex): 7A (cont...)
Register Name
cnfg_sync_pulses
Bit 7
Bit 6
FINAL
Description
Bit 5
(R/W) Register to configure the
Default Value
Sync outputs available from TO10
and TO11 and select the source
for the 2 kHz and 8 kHz outputs
from T01 - TO7.
Bit 4
Bit 3
8k_invert
2k_8k_from_T4
Bit No.
0
DATASHEET
Description
Bit Value
2k_pulse
Register bit to enable the 2 kHz output from TO11
to be either pulsed or 50:50 duty cycle. Output TO3
must be enabled to use “pulsed output” mode on
output TO10, and then the pulse width on TO11 will
be defined by the period of the output programmed
on TO3.
0
1
Bit 2
8k_pulse
Bit 1
2k_invert
0000 0000
Bit 0
2k_pulse
Value Description
2 kHz TO11 output not pulsed.
2 kHz TO11 output pulsed.
Address (hex): 7B
Register Name
cnfg_sync_phase
Bit 7
Bit 6
indep_FrSync/
MFrSync
Sync_OC-N_
rates
Bit No.
7
6
[5:2]
Description
Bit 5
(R/W) Register to configure the
behavior of the synchronization
for the external frame reference.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
Sync_phase
Description
Bit Value
indep_FrSync/MFrSync
This allows the option of either maintaining
alignment of FrSync and other clock outputs during
synchronization from the SYNC2K input, or whether
to not maintain alignment to all clocks and so not
disturb any of the output clocks
0
Sync_OC-N_rates
This allows the SYNC2K input to synchronize the
OC-3 derived clocks in order to maintain alignment
between the FrSync output and output clocks and
allow a finer sampling precision of the SYNC2K
input of either 19.44 MHz or 38.88 MHz.
0
1
1
Value Description
MFrSync & FrSync outputs are always aligned with
other output clocks.
MFrSync & FrSync outputs are independent of other
output clocks.
The OC-N rate clocks are not affected by the
SYNC2K input. The SYNC2K input is sampled with a
6.48 MHz precision. 6.48MHz should be provided
as the input reference clock.
Allows the SYNC2K to operate with a 19.44 MHz or
38.88 MHz input clock reference. Input sampling
and output alignment to 19.44 MHz is used when
the current clock input is 19.44 MHz, otherwise
38.88 MHz sampling precision is used.
Not used.
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Address (hex): 7B (cont...)
Register Name
cnfg_sync_phase
Bit 7
Bit 6
indep_FrSync/
MFrSync
Sync_OC-N_
rates
Bit No.
[1:0]
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure the
behavior of the synchronization
for the external frame reference.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000
Bit 0
Sync_phase
Description
Bit Value
Sync_phase
Register to control the sampling of the external Sync
input. Nominally the falling edge of the input is
aligned with the falling edge of the reference clock.
The margin is ±0.5 U.I. (Unit Interval).
00
01
10
11
Value Description
On target.
0.5 U.I. early
1 U.I. late
0.5 U.I. late.
Address (hex): 7C
Register Name
Bit 7
cnfg_sync_monitor
Bit 6
ph_offset_ramp
Bit No.
7
[6:4]
Description
Bit 5
(R/W) Register to configure the
Default Value
external Sync input monitor. It
also has a bit to control the phase
offset automatic ramping feature.
Bit 4
Bit 3
Sync_monitor_limit
Bit 1
Bit 0
Sync_reference_source
Description
Bit Value
ph_offset_ramp
Register bit to force an internal phase offset
calibration, see Reg. 71, Cnfg_Phase_Offset.
The calibration routine is transparent to the outside
and puts the device in holdover while it internally
ramps the phase offset to zero, resets all internal
output and feedback dividers and then ramps the
phase offset to the current programmed value from
Reg. 70 or 71., holdover is then turned off. All this is
transparent to the outside with no change in output
phase offset visible.
0
Sync_monitor_limit
An alternative to allowing the external Sync input to
synchronize the outputs, is to use the Sync monitor
block to alarm when the external Sync input does
not align with the output within a certain number of
input clock cycles. This register defines the limit in
UI of the selected reference source. If the alignment
does not occur within this limit, then Sync alarm will
be raised, see Reg. 09 Bit 7.
000
001
010
011
100
101
110
111
Revision 3.02/October 2005 © Semtech Corp.
Bit 2
0010 1011
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1
Value Description
Phase offset automatically ramped from the old
value to the new value when there is a change in
Reg. 70 or 71.
Start phase offset internal calibration routine. This
bit is reset to 0 when this is complete.
Sync alarm raised beyond ±1 UI.
Sync alarm raised beyond ±2 UI.
Sync alarm raised beyond ±3 UI.
Sync alarm raised beyond ±4 UI.
Sync alarm raised beyond ±5 UI.
Sync alarm raised beyond ±6 UI.
Sync alarm raised beyond ±7 UI.
Sync alarm raised beyond ±8 UI.
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Address (hex): 7C (cont...)
Register Name
cnfg_sync_monitor
Bit 7
Bit 6
ph_offset_ramp
Bit No.
[3:0]
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure the
Default Value
external Sync input monitor. It
also has a bit to control the phase
offset automatic ramping feature.
Bit 4
Bit 3
Bit 2
Sync_monitor_limit
0010 1011
Bit 1
Bit 0
Sync_reference_source
Description
Bit Value
Sync_reference_source
The external Sync reference can only be associated
with a particular input reference. When automatic
external Sync enabling is selected in Reg. 34 Bit 7,
the external Sync input will only be enabled when
locked to the selected source. This can be used to
associate the Frame Sync reference with a
reference clock for Master/Slave operation.
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Value Description
Not used.
External Sync associated with input I1.
External Sync associated with input I2.
External Sync associated with input I3.
External Sync associated with input I4.
External Sync associated with input I5.
External Sync associated with input I6.
External Sync associated with input I7.
External Sync associated with input I8.
External Sync associated with input I9.
External Sync associated with input I10.
External Sync associated with input I11.
External Sync associated with input I12.
External Sync associated with input I13.
External Sync associated with input I14.
Not used.
Address (hex): 7D
Register Name
Bit 7
cnfg_interrupt
Bit 6
Description
Bit 5
(R/W) Register to configure
interrupt output.
Bit 4
Bit 3
Bit 2
GPO_en
Bit No.
[7:3]
Description
Bit Value
Default Value
0000 0010
Bit 1
Bit 0
tristate_en
int_polarity
Value Description
Not used.
-
-
2
GPO_en
(Interrupt General Purpose Output). If the interrupt
output pin is not required, then setting this bit will
allow the pin to be used as a general purpose
output. The pin will be driven to the state of the
polarity control bit, int_polarity.
0
1
Interrupt output pin used for interrupts.
Interrupt output pin used for GPO purpose.
1
tristate_en
The interrupt can be configured to be either
connected directly to a processor, or wired together
with other sources.
0
1
Interrupt pin always driven when inactive.
Interrupt pin only driven when active, Highimpedance when inactive.
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ACS8520 SETS
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Address (hex): 7D (cont...)
Register Name
cnfg_interrupt
Bit 7
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W) Register to configure
interrupt output.
Bit 4
Bit 3
Bit 2
GPO_en
Bit No.
0
Description
Bit Value
int_polarity
The interrupt pin can be configured to be active
High or Low.
0
1
Default Value
0000 0010
Bit 1
Bit 0
tristate_en
int_polarity
Value Description
Active Low - pin driven Low to indicate active
interrupt.
Active High - pin driven High to indicate active
interrupt.
Address (hex): 7E
Register Name
cnfg_protection
Bit 7
Bit 6
Description
Bit 5
(R/W) Protection register to
protect against erroneous
software writes.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
1000 0101
Bit 0
protection_value
Bit No.
[7:0]
Description
Bit Value
protection_value
This register can be used to ensure that the
software writes a specific value to this register,
before being able to modify any other register in the
device. Three modes of protection are offered,
(i) protected
(ii) fully unprotected
(iii) single unprotected.
When protected, no other register in the device can
be written to. When fully unprotected, any writeable
register in the device can be written to. When single
unprotected, only one register can be written before
the device automatically re-protects itself.
Revision 3.02/October 2005 © Semtech Corp.
Value Description
0000 0000 –
1000 0100
Protected mode.
1000 0101
Fully unprotected.
1000 0110
Single unprotected.
1000 0111 –
1111 1111
Protected mode.
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Address (hex): 7F
Register Name
Bit 7
cnfg_uPsel
Bit 6
FINAL
Description
Bit 5
DATASHEET
(R/W)* Register reflecting the
value on the UPSEL device pins
following reset, and writeable in
EPROM mode.
Bit 4
Bit 3
Default Value
Bit 2
Bit 1
0000 0000**
Bit 0
upsel_value
Bit No.
Description
Bit Value
[7:3]
Not used.
-
[2:0]
upsel_value
This register defaults to reflecting the value present
on the UPSEL pins of the device at reset. At reset
this is used to set the mode of the microprocessor
interface. Following power-up, these pins have no
further effect on the microprocessor interface.
*In order that the device can be “booted” from an
EPROM and subsequently communicate with a
processor, this register is programmable in EPROM
mode. The value programmed in location 7F of the
EPROM will be the value loaded into this register.
000
001
010
011
100
101
110
111
(value at reset)
Value Description
Not used.
Interface in EPROM boot mode.
Interface in Multiplexed mode.
Interface in Intel mode.
Interface in Motorola mode.
Interface in Serial mode.
Not used.
Not used.
**The default of this register is entirely dependent
on the value of the pins at reset.
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ACS8520 SETS
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Electrical Specifications
FINAL
JTAG
The JTAG connections on the ACS8520 allow a full
boundary scan to be made. The JTAG implementation is
fully compliant to IEEE 1149.1[5], with the following minor
exceptions, and the user should refer to the standard for
further information.
1. The output boundary scan cells do not capture data
from the core, and so do not support INTEST. However
this does not affect board testing.
2. In common with some other manufacturers, pin TRST
is internally pulled Low to disable JTAG by default. The
standard is to pull High. The polarity of TRST is as the
standard: TRST High to enable JTAG boundary scan
mode, TRST Low for normal operation.
The JTAG timing diagram is shown in Figure 22.
DATASHEET
recommendation K.41[16]. Semtech protection devices
are recommended for this purpose (see separate
Semtech data book).
ESD Protection
Suitable precautions should be taken to protect against
electrostatic damage during handling and assembly. This
device incorporates ESD protection structures that
protect the device against ESD damage at ESD input
levels up to at least ±2 kV using the Human Body Model
(HBD) MIL-STD-883D Method 3015.7, for all pins except
pins 24, 25, 26 and 27 (AMI I/Os) which are protected up
to at least ±1 kV.
Latchup Protection
Over-voltage Protection
The ACS8520 may require Over-Voltage Protection on
input reference clock ports according to ITU
This device is protected against latchup for input current
pulses of magnitude up to at least ±100 mA to JEDEC
Standard No. 78 August 1997.
Figure 22 JTAG Timing
tCYC
TCK
tSUR
tHT
TMS
TDI
tDOD
TDO
F8110D_022JTAGTiming_01
Table 31 JTAG Timing (for use with Figure 22)
Parameter
Symbol
Minimum
Typical
Maximum
Units
Cycle Time
tCYC
50
-
-
ns
TMS/TDI to TCK rising edge time
tSUR
3
-
-
ns
TCK rising to TMS/TDI hold time
tHT
23
-
-
ns
tDOD
-
-
5
ns
TCK falling to TDO valid
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Maximum Ratings
FINAL
DATASHEET
Important Note: The Absolute Maximum Ratings, Table 32, are stress ratings only, and functional operation of the
device at conditions other than those indicated in the Operating Conditions sections of this specification are not
implied. Exposure to the absolute maximum ratings for an extended period may reduce the reliability or useful lifetime
of the product.
Table 32 Absolute Maximum Ratings
Parameter
Symbol
Minimum
Maximum
Units
Supply Voltage VDDa, VDDb, VDDc, VDDd,
VD1+, VD2+, VD3+, VA1+, VA2+, VA3+,
VAMI+, VDD_DIFFa, VDD_DIFFb
VDD
-0.5
3.6
V
Power Supply (DC voltage) VDD5
VDD5
-
5.5
V
VIN
-
5.5
V
VOUT
-
5.5
V
Input Voltage (non-supply pins)
Output Voltage (non-supply pins)
TA
-40
+85
oC
TSTOR
-50
+150
oC
Ambient Operating Temperature Range
Storage Temperature
Operating Conditions
Table 33 Operating Conditions
Parameter
Symbol
Minimum
Typical
Maximum
Units
Power Supply (dc voltage)
VDDa, VDDb, VDDc, VDDd, VD1+, VD2+,
VD3+, VA1+, VA2+, VA3+, VAMI+,
VDD_DIFFa, VDD_DIFFb
VDD
3.0
3.3
3.6
V
Power Supply (DC voltage) VDD5
VDD5
3.0
3.3/5.0
5.5
V
Ambient Temperature Range
TA
-40
-
+85
oC
Supply Current
(Typical - one 19 MHz output)
IDD
-
130
222
mA
Total Power Dissipation
PTOT
-
430
800
mW
DC Characteristics
Table 34 DC Characteristics: TTL Input Port
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
VIN High
VIH
2
-
-
V
VIN Low
VIL
-
-
0.8
V
Input Current
IIN
-
-
10
µA
Revision 3.02/October 2005 © Semtech Corp.
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DATASHEET
Table 35 DC Characteristics: TTL Input Port with Internal Pull-up
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
VIN High
VIH
2
-
-
V
VIN Low
VIL
-
-
0.8
V
Pull-up Resistor
PU
25
-
90
kΩ
Input Current
IIN
-
-
120
µΑ
Table 36 DC Characteristics: TTL Input Port with Internal Pull-down
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
VIN High
VIH
2
-
-
V
VIN Low
VIL
-
-
0.8
V
Pull-down Resistor
PD
25
-
90
kΩ
Input Current
IIN
-
-
120
µA
Symbol
Minimum
Typical
Maximum
Units
VOUT Low (lOL = 4mA)
VOL
0
-
0.4
V
VOUT High (lOH = 4mA)
VOH
2.4
-
-
V
ID
-
-
4
mA
Table 37 DC Characteristics: TTL Output Port
Across all operating conditions, unless otherwise stated
Parameter
Drive Current
Table 38 DC Characteristics: PECL Input/Output Port
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
PECL Input Low Voltage
Differential Inputs (Note ii)
VILPECL
VDD-2.5
-
VDD-0.5
V
PECL Input High Voltage
Differential Inputs (Note ii)
VIHPECL
VDD-2.4
-
VDD-0.4
V
Input Differential Voltage
VIDPECL
0.1
-
1.4
V
VILPECL_S
VDD-2.4
-
VDD-1.5
V
PECL Input Low Voltage
Single-ended Input (Note iii)
Revision 3.02/October 2005 © Semtech Corp.
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DATASHEET
Table 38 DC Characteristics: PECL Input/Output Port (cont...)
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
VILPECL_S
VDD-1.3
-
VDD-0.5
V
Input High Current
Input Differential Voltage VID = 1.4V
IIHPECL
-10
-
+10
µA
Input Low Current
Input Differential Voltage VID = 1.4V
IILPECL
-10
-
+10
µA
PECL Output Low Voltage (Note iv)
VOLPECL
VDD-2.10
-
VDD-1.62
V
PECL Output High Voltage (Note iv)
VOHPECL
VDD-1.25
-
VDD-0.88
V
PECL Output Differential Voltage (Note iv)
VODPECL
580
-
900
mV
PECL Input High Voltage
Single-ended Input (Note iii)
Notes: (i) Unused differential input ports should be left floating and set in LVDS mode, or the positive and negative inputs tied to VDD and GND
respectively.
(ii) Assuming a differential input voltage of at least 100 mV.
(iii) Unused differential input terminated to VDD -1.4 V.
(iv) With 50 Ω load on each pin to VDD -2 V, i.e. 82 Ω to GND and 130 Ω to VDD.
Figure 23 Recommended Line Termination for PECL Input/Output Ports
VDD
130 Ω
n x 8 kHz,
1.544/2.048 MHz, ZO = 50Ω
6.48 MHz,
19.44 MHz,
82 Ω
38.88 MHz,
ZO = 50Ω
51.84 MHz,
77.76 MHz or
155.52 MHz
VDD
I5POS
TO6POS
130 Ω
I5NEG
TO6NEG
ZO = 50Ω
ZO = 50Ω
130 Ω
82 Ω
82 Ω
GND
VDD
VDD
I6POS
TO7POS
130 Ω
I6NEG
TO7NEG
ZO = 50Ω
ZO = 50Ω
130 Ω
82 Ω
82 Ω
GND
Revision 3.02/October 2005 © Semtech Corp.
Fully
Programmable
Output Frequencies
82 Ω
GND
130 Ω
n x 8 kHz,
1.544/2.048 MHz, ZO = 50Ω
6.48 MHz,
19.44 MHz,
38.88 MHz,
82 Ω
ZO = 50Ω
51.84 MHz,
77.76 MHz or
155.52 MHz
130 Ω
130 Ω
Fully
Programmable
Output Frequencies
82 Ω
ZO = Transmission line Impedance
VDD = +3.3 V
n = Integer 1 to 12,500
Page 136
GND
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DATASHEET
Table 39 DC Characteristics: LVDS Input/Output Port
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
VVRLVDS
0
-
2.40
V
VDITH
-100
-
+100
mV
VIDLVTSDS
0.1
-
1.4
V
RTERM
95
100
105
Ω
LVDS Output High Voltage
(Note (i))
VOHLVDS
-
-
1.585
V
LVDS Output Low Voltage
(Note (i))
VOLLVDS
0.885
-
-
V
LVDS Differential Output Voltage
VODLVDS
250
-
450
mV
LVDS Change in Magnitude of Differential
Output Voltage for complementary States
(Note (i))
VDOSLVDS
-
-
25
mV
LVDS Output Offset Voltage
Temperature = 25oC (Note (i))
VOSLVDS
1.125
-
1.275
V
LVDS Input Voltage Range
Differential Input Voltage = 100 mV
LVDS Differential Input Threshold
LVDS Input Differential Voltage
LVDS Input Termination Resistance
Must be placed externally across the LVDS
± input pins of ACS8520. Resistor should
be 100 Ω with 5% tolerance
Note:
(i) With 100 Ω load between the differential outputs.
Figure 24 Recommended Line Termination for LVDS Input/Output Ports
n x 8 kHz,
1.544/2.048 MHz,
6.48 MHz,
19.44 MHz,
38.88 MHz,
51.84 MHz,
77.76 MHz or
155.52 MHz
n x 8 kHz,
1.544/2.048 MHz,
6.48 MHz,
19.44 MHz,
38.88 MHz,
51.84 MHz,
77.76 MHz or
155.52 MHz
ZO = 50Ω
ZO = 50Ω
I5POS
100 Ω
ZO = 50Ω
ZO = 50Ω
TO6POS
I5NEG
TO6NEG
I6POS
TO7POS
100 Ω
I6NEG
TO7NEG
ZO = 50Ω
ZO = 50Ω
100 Ω
Fully
Programmable
Output Frequencies
100 Ω
Fully
Programmable
Output Frequencies
ZO = 50Ω
ZO = 50Ω
ZO = Transmission line Impedance
VDD = +3.3 V
n = integer 1 to 12,500
Revision 3.02/October 2005 © Semtech Corp.
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DC Characteristics: AMI Input/Output Port
(Across all operating Conditions, unless otherwise stated.)
The Alternate Mark Inversion (AMI) signal is DC balanced
and consists of positive and negative pulses with a peakto-peak voltage of 2.0 ±0.2 V.
The electrical specifications are taken from option a) of
Table 2/G.703 - Digital 64 kbit/s centralized clock
interface, from ITU G.703[6].
The electrical characteristics of the 64 kbit/s interface
are as follows:
Nominal bit rate: 64 kbit/s. The tolerance is determined
by the network clock stability.
DATASHEET
There should be a symmetrical pair carrying the
composite timing signal (64 kHz and 8 kHz). The use of
transformers is recommended.
Over-voltage protection requirement: refer to
Recommendation K.41[16]
Code conversion rules:
The data signals are coded in AMI code with 100% duty
cycle. The composite clock timing signals convey the
64 kHz bit-timing information using AMI coding with a
50% to 70% duty ratio and the 8 kHz octet phase
information by introducing violations in the code rule. The
structure of the signals and voltage level are shown in
Figure 25, Figure 26 and Figure 27.
Table 40 DC Characteristics: AMI Input/Output Port
Across all operating conditions, unless otherwise stated
Parameter
Symbol
Minimum
Typical
Maximum
Units
Input Pulse Width
tPW
1.56
7.8
14.04
µs
Input Pulse Rise/Fall Time
tR/F
-
-
5
µs
AMI Input Voltage High
VIH AMI
2.5
-
VDD + 0.3
V
AMI Input Voltage Middle
VVIM AMI
1.5
1.65
1.8
V
AMI Input Voltage Low
VVIL AMI
0
-
1.4
V
AMI Output Current Drive
IAMIOUT
-
-
20
mA
AMI Output High Voltage
Output Current = 20mA
VOH AMI
VDD - 0.16
-
-
V
AMI Output Low Voltage
Output Current = 20mA
VOL AMI
-
-
0.16
V
Nominal Test Load Impedance
RTEST
-
110
-
Ω
“Mark” Amplitude After Transformer
VMARK
0.9
1.0
1.1
V
“Space” Amplitude After Transformer
VSPACE
- 0.1
0
0.1
V
Revision 3.02/October 2005 © Semtech Corp.
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DATASHEET
Figure 25 Signal Structure of 64 kHz/8 kHz Central Clock Interface)
6
Bit Number
7
8
1
2
3
4
5
6
7
8
1
2
Timing
Violation
Violation
Octet Start
Octet Start
15.6 us
7.8 us
+1.0 VIH
1V
2 V p-p
0 VIM
1V
-1.0 VIL
F8530D_019SigStrucCCI_01
Note...after suitable input/output transformer (also see G.703[6]).
Figure 26 AMI Input and Output Signal Levels
15.6 us
Signal structure of 64 kHz/8 kHz central
clock interface after suitable transformer.
7.8 us
+VDD
15.6 us
7.8 us
0V
+1.0 VIH
I1
C1
1V
2 V p-p
T08POS
0 VIM
C2
15.6 us
1V
-1.0 VIL
I2
T08NEG
7.8 us
+VDD
C1
0V
F8530D_020AMIIPandOPSigLevels_02
Revision 3.02/October 2005 © Semtech Corp.
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FINAL
DATASHEET
Figure 27 Recommended Line Termination for AMI Output/Output Ports
Turns
ratio
3:1
AMI input
signal
I1
C1
C2
AMI input
signal
I2
AMI output signal
to external devices
TO8POS
Rload
C3
GND
TO8NEG
C1
F8530D_023AMI_lineterm_04
Note...The AMI inputs I1 and I2 should be connected to the external AMI clock source by 470 nF coupling capacitor C1.
The AMI differential output T08POS/T08NEG should be coupled to a line transformer with a turns ratio of 3:1.
Components C2 = 470 pF and C3 = 2 nF. If a transformer with a turns ratio of 1:1 is used, a 3:1 ratio potential
divider Rload must be used to achieve the required 1 V p-p voltage level for the positive and negative pulses.
Jitter Performance
Output jitter generation measured over 60 second interval, UI p-p max measured using C-MAC E2747 12.800 MHz
TCXO on ICT Flexacom tester.
Table 41 Output Jitter Generation
Test Definition
Specification
G813[11] for 155 MHz o/p option 1
Conditions
Filter
Bandwidth
65 kHz - 1.3 MHz
4 Hz
I/P Freq
19 MHz
Lock Mode
Direct lock
Jitter Spec
ACS8520 Jitter
UI
UI (TYP)
0.1 p-p
8k lock
G813[11] & G812[10] for 2.048 MHz option 1
G813
[11]
for 155 MHz o/p option 2
G812[10] for 1.544 MHz o/p
Revision 3.02/October 2005 © Semtech Corp.
0.067 p-p
0.065 p-p
20 Hz - 100 kHz
4 Hz
2.048 MHz 8k lock
12 kHz - 1.3 MHz
18 Hz
19 MHz
Direct lock/ 0.1 p-p
8k lock
0.072 p-p
12 kHz - 1.3 MHz
8 Hz
19 MHz
Direct lock/ 0.1 p-p
8k lock
0.072 p-p
12 kHz - 1.3 MHz
4 Hz
19 MHz
Direct lock/ 0.1 p-p
8k lock
0.078 p-p
12 kHz - 1.3 MHz
2.5 Hz
19 MHz
Direct lock/ 0.1 p-p
8k lock
0.078 p-p
12 kHz - 1.3 MHz
1.2 Hz
19 MHz
Direct lock/ 0.1 p-p
8k lock
0.078 p-p
12 kHz - 1.3 MHz
0.6 Hz
19 MHz
Direct lock/ 0.1 p-p
8k lock
0.076 p-p
10 Hz - 40 kHz
4 Hz
1.544 MHz 8k lock
Page 140
0.05 p-p
0.05 p-p
0.012 p-p
0.006 p-p
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DATASHEET
Table 41 Output Jitter Generation
Test Definition
Specification
Conditions
Filter
Bandwidth
I/P Freq
Lock Mode
Jitter Spec
ACS8520 Jitter
UI
UI (TYP)
G812[10] for 155 MHz electrical
500 Hz - 1.3 MHz
4 Hz
19 MHz
8k lock
0.5 p-p
0.118 p-p
G812[10] for 155 MHz electrical
65 kHz - 1.3 MHz
4 Hz
19 MHz
8k lock
0.075 p-p
0.065 p-p
ETS-300-462-3[3] for 2.048 MHz SEC o/p
20 Hz - 100 kHz
4 Hz
2.048 MHz 8k lock
0.5 p-p
0.012 p-p
ETS-300-462-3[3] for 2.048 MHz SEC o/p
49 Hz - 100 kHz
4 Hz
2.048 MHz 8k lock
0.2 p-p
0.012 p-p
20 Hz - 100 kHz
4 Hz
2.048 MHz 8k lock
0.05 p-p
0.012 p-p
ETS-300-462-5[4] for 155 MHz o/p
500 Hz - 1.3 MHz
4 Hz
19 MHz
8k lock
0.5 p-p
0.118 p-p
ETS-300-462-5[4] for 155 MHz o/p
65 kHz - 1.3 MHz
4 Hz
19 MHz
8k lock
0.1 p-p
0.067 p-p
GR-253-CORE[17] net i/f, 51.84 MHz o/p
100 Hz - 0.4 MHz
4 Hz
19 MHz
8k lock
1.5 p-p
0.027 p-p
20 kHz to 0.4 MHz 4 Hz
19 MHz
8k lock
0.15 p-p
0.017 p-p
GR-253-CORE[17] net i/f, 155 MHz o/p
500 Hz - 1.3 MHz
4 Hz
19 MHz
8k lock
1.5 p-p
0.118 p-p
GR-253-CORE[17] net i/f, 155 MHz o/p
65 kHz - 1.3 MHz
4 Hz
19 MHz
8k lock
0.15 p-p
0.067 p-p
GR-253-CORE[17]cat II elect i/f, 155 MHz
12 kHz - 1.3 MHz
4 Hz
19 MHz
8k lock
0.1 p-p
0.076 p-p
0.01 rms
0.006 rms
0.1 p-p
0.018 p-p
0.01 rms
0.003 rms
0.1 p-p
0.001 p-p
0.01 rms
<0.001 rms
[3]
ETS-300-462-3
[17]
GR-253-CORE
for 2.048 MHz SSU o/p
net i/f, 51.84 MHz o/p
GR-253-CORE[17] cat II elect i/f, 51.84 MHz
GR-253-CORE[17] DS1 i/f, 1.544 MHz
12 kHz - 400 kHz
10 Hz - 40 kHz
4 Hz
4 Hz
19 MHz
8k lock
1.544 MHz 8k lock
AT&T 62411[2] for 1.544 MHz
10 Hz - 8 kHz
4 Hz
1.544 MHz 8k lock
0.02 rms
<0.001 rms
AT&T 62411[2] for 1.544 MHz
8 Hz - 40 kHz
4 Hz
1.544 MHz 8k lock
0.025 rms
<0.001 rms
AT&T 62411[2] for 1.544 MHz
10 Hz - 40 kHz
4 Hz
1.544 MHz 8k lock
0.025 rms
<0.001 rms
Broadband
4 Hz
1.544 MHz 8k lock
0.05 rms
<0.001 rms
G-742[8] for 2.048 MHz
DC - 100 kHz
4 Hz
2.048 MHz 8k lock
0.25 rms
0.012 rms
G-742[8] for 2.048MHz
18 kHz - 100 kHz
4 Hz
2.048 MHz 8k lock
0.05 p-p
0.012 p-p
G-736[7] for 2.048MHz
20 Hz - 100 kHz
4 Hz
2.048 MHz 8k lock
0.05 p-p
0.012 p-p
GR-499-CORE[18] & G824[14] for 1.544 MHz
10 Hz - 40kHz
4 Hz
1.544 MHz 8k lock
5.0 p-p
0.006 p-p
GR-499-CORE[18] & G824[14] for 1.544 MHz
8 kHz - 40kHz
4 Hz
1.544 MHz 8k lock
0.1 p-p
0.006 p-p
GR-1244-CORE[19] for 1.544 MHz
> 10 Hz
4 Hz
1.544 MHz 8k lock
0.05 p-p
0.006 p-p
AT&T 62411
[2]
for 1.544 MHz
Note...This table is only for comparing the ACS8520 output jitter performance against values and quoted in various specifications for given
conditions. It should not be used to infer compliance to any other aspects of these specifications.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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Input/Output Timing
FINAL
DATASHEET
Figure 28 Input/Output Timing with Phase Build-out Off
Input/Output
Delay
8 kHz input
Output
Min/Max Phase Alignment
(FrSync Alignment switched on)
MFrSync (2 kHz)
+8.2 ± 1.5 ns
8 kHz output
FrSync (8 kHz)
-1.2 ± 0.5 ns
6.48 MHz input
+4.7 ± 1.5 ns
6.48 MHz output
19.44 MHz input
8 kHz
-0.4 ± 0.5 ns
2 kHz
-0.0 ± 0.5 ns
DS1 (1.544 MHz)
-1.2 ± 1.25 ns
E1 (2.048 MHz)
-1.2 ± 1.25 ns
DS3 (44.736 MHz)
-3.75 ± 1.25 ns
E3 (34.368 MHz)
-3.75 ± 1.25 ns
6.48 MHz
-3.75 ± 1.25 ns
19.44 MHz
-3.75 ± 1.25 ns
25.92 MHz
-3.75 ± 1.25 ns
38.88 MHz
-3.75 ± 1.25 ns
51.84 MHz
-3.75 ± 1.25 ns
77.76 MHz
-3.75 ± 1.25 ns
155.52 MHz
-3.75 ± 1.25 ns
311.04 MHz
-3.75 ± 1.25 ns
+4.3 ± 1.5 ns
19.44 MHz output
25.92 MHz input
+4.7 ± 1.5 ns
25.92 MHz output
38.88 MHz input
+4.6 ± 1.5 ns
38.88 MHz output
51.84 MHz input
+3.0 ± 1.5 ns
51.84 MHz output
77.76 MHz input
+5.3 ± 1.5 ns
77.76 MHz output
155.52 MHz input
+5.3 ± 1.5 ns
155.52 MHz output
F8525D_021IP_OPTiming_02
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
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Package Information
FINAL
DATASHEET
Figure 29 LQFP Package
D
2
D1 1
3
AN2
AN3
1
Section A-A
R1
S
E
1
2
R2
B
AN1
E1
A
A
B
3
AN4
L
4
L1
5
1 2 3
b
Section B-B
7
e
A
A2
c
c1
7
7
Seating plane
A1 6
b1 7
b
8
Notes
1
The top package body may be smaller than the bottom package body by as much as 0.15 mm.
2
To be determined at seating plane.
3
Dimensions D1 and E1 do not include mold protrusion. Allowable protrusion is 0.25 mm per side.
D1 and E1 are maximum plastic body size dimensions including mold mismatch.
4
Details of pin 1 identifier are optional but will be located within the zone indicated.
5
Exact shape of corners can vary.
6
A1 is defined as the distance from the seating plane to the lowest point of the package body.
7
These dimensions apply to the flat section of the lead between 0.10 mm and 0.25 mm from the lead tip.
8
Shows plating.
Table 42 100 Pin LQFP Package Dimension Data (for use with Figure 29)
100 LQFP
Package
Dimensions
in mm
D/E
D1/
E1
Min.
-
-
Nom.
Max.
e
AN1 AN2 AN3 AN4
-
11o
11o
0o
0o
16.00 14.00 1.50 0.10 1.40 0.50 12o
12o
-
3.5o
-
13o
13o
-
7o
-
-
-
A
A1
A2
1.40 0.05 1.35
1.60 0.15 1.45
Revision 3.02/October 2005 © Semtech Corp.
-
Page 143
R1
R2
L
0.08 0.08 0.45
-
L1
-
0.60 1.00
(ref)
0.20 0.75
-
S
b
b1
c
c1
0.20 0.17 0.17 0.09 0.09
-
0.22 0.20
-
-
-
0.27 0.23 0.20 0.16
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Thermal Conditions
FINAL
DATASHEET
The device is rated for full temperature range when this package is used with a 4 layer or more PCB. Copper coverage
must exceed 50%. All pins must be soldered to the PCB. Maximum operating temperature must be reduced when the
device is used with a PCB with less than these requirements.
Figure 30 Typical 100 Pin LQFP Footprint
1.85 mm
Not Drawn to Scale
Pitch 0.5 mm
18.3 mm
17.0 mm (i)
14.6 mm
Width 0.3 mm
F8530D_030QFNFootprt100_02
Notes: (i) Solderable to this limit.
(ii) Square package - dimensions apply in both X and Y directions.
(iii) Typical example. The user is responsible for ensuring compatibility with PCB manufacturing process, etc.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Application Information
FINAL
DATASHEET
Figure 31 Simplified Application Schematic
VDD
IC2
VDD5v
P1
VDD2
EZ1086CT-3.3
3
5v
VDD3
2
VIN
VOUT
1
0v
VDDA
GND
(+)
(+)
term_connect
100uF
C2
Power supply and ground
connections to 'star'
connect back to these
decoupling capacitors at
the regulator and only
connect together at this
point
C7
100nF
C4
100nF
10uF_TANT
C3
AGND
DGND3
ZD1
BZV90C-5.6v
Optional EPROM interface
selection
Optional Processor/EPROM
interface type selection
DGND2
DGND
Decoupling capacitor, C21 should be placed close to the xtal
pins that are being decoupled
RDY RDB CSB
ALE WRB
Int
CC parts are easily cut links that can also take SM
capacitors or Ohm resistor links.
SrSwit
All tcxo options to be placed as close as possible to IC1,
with short output track.
O1
O2
VDD
O3
O4
C29
C9
VDDA
O5
100nF
100nF
O9
DGND
AGND
C10
100nF
AGND
R1
X1
10R
2 vdd
output
1
VDD3
gnd2
5
C11
100nF
C21
4
optn
VDDA
R6
DGND3
10R
C12
100nF
3 gnd1
Vectron
AGND
DGND
VDD2
C6
100nF
C5
AGND
TRST
IC1
IC2
AGND1
VA1+
TMS
INTREQ
TCK
REFCLK
DGND1
VD1+
VD3+
DGND3
DGND2
VD2+
IC3
SRCSW
VA2+
AGND2
TDO
IC4
TDI
I1
I2
RDY
PORB
ALE
RDB
WRB
CSB
A0
A1
A2
A3
A4
A5
A6
DGNDd
VDDd
UPSEL0
UPSEL1
UPSEL2
I14
I13
I12
I11
I10
I9
I8
IC1
ACS8520
VAMI+
TO8NEG
TO8POS
GND_AMI
FrSync
MFrSync
GND_DIFFa
VDD_DIFFa
TO6POS
TO6NEG
TO7POS
TO7NEG
GND_DIFFb
VDD_DIFFb
I5POS
I5NEG
I6POS
I6NEG
VDD5
SYNC2K
I3
I4
I7
DGNDa
VDDa
VDDA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
C8
1nF
DGND
VDD
100nF
C13
DGND
Optional
UPSEL0 Processor
UPSEL1 interface type
UPSEL2 selection
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
txco
12.8MHz
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
DGNDc
VDDc
VDDb
DGNDb
TO1
TO2
TO3
VA3+
AGND3
TO4
TO5
TO9
IC5
IC6
IC7
MSTSLVB
SONSDHB
VDD
100nF
All decoupling capacitors, C29,
C9, C13, C14, C15, C6, C5,
C12, C11, C10,C32 should be
placed close to the IC1 pins that
are being decoupled
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
DGND
(+)
10uF_TANT
VDD
DGND2
C14
100nF
DGND
VDD2
VDD2
C15
C32
100nF
100nF
DGND2
DGND2
C23
100n
9
7
T1
4
6
Pe-68865
R41
optn
C16
C17
R38
470nF
470nF
I1
I2
optn
optn
C22
O8P
DGND2
I4
I3
DGND
I10
I8
I7
I9
I12
I11
I14
I13
DGND
F8520D_031EvalBdSchem_01
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Abbreviations
AMI
APLL
BITS
DFS
DPLL
DS1
DTO
E1
I/O
LOF
LOS
LQFP
LVDS
MTIE
NE
OCXO
PBO
PDH
PECL
PFD
PLL
POR
ppb
ppm
p-p
R/W
rms
RO
RoHS
SDH
SEC
SETS
SONET
SSU
STM
TDEV
TCXO
UI
WEEE
FINAL
References
Alternate Mark Inversion
Analogue Phase Locked Loop
Building Integrated Timing Supply
Digital Frequency Synthesis
Digital Phase Locked Loop
1544 kbit/s interface rate
Discrete Time Oscillator
2048 kbit/s interface rate
Input - Output
Loss of Frame Alignment
Loss Of Signal
Low profile Quad Flat Pack
Low Voltage Differential Signal
Maximum Time Interval Error
Network Element
Oven Controlled Crystal Oscillator
Phase Build-out
Plesiochronous Digital Hierarchy
Positive Emitter Coupled Logic
Phase and Frequency Detector
Phase Locked Loop
Power-On Reset
parts per billion
parts per million
peak-to-peak
Read/Write
root-mean-square
Read Only
Restrictive Use of Certain Hazardous
Substances (directive)
Synchronous Digital Hierarchy
SDH/SONET Equipment Clock
Synchronous Equipment Timing source
Synchronous Optical Network
Synchronization Supply Unit
Synchronous Transport Module
Time Deviation
Temperature Compensated Crystal
Oscillator
Unit Interval
Waste Electrical and Electronic
Equipment (directive)
Revision 3.02/October 2005 © Semtech Corp.
DATASHEET
[1] ANSI T1.101-1999 (1999)
Synchronization Interface Standard
[2] AT & T 62411 (12/1990)
ACCUNET® T1.5 Service description and Interface
Specification
[3] ETSI ETS 300 462-3, (01/1997)
Transmission and Multiplexing (TM); Generic
requirements for synchronization networks; Part 3: The
control of jitter and wander within synchronization
networks
[4] ETSI ETS 300 462-5 (09/1996)
Transmission and Multiplexing (TM); Generic
requirements for synchronization networks; Part 5: Timing
characteristics of slave clocks suitable for operation in
Synchronous Digital Hierarchy (SDH) equipment
[5] IEEE 1149.1 (1990)
Standard Test Access Port and Boundary-Scan
Architecture
[6] ITU-T G.703 (10/1998)
Physical/electrical characteristics of hierarchical digital
interfaces
[7] ITU-T G.736 (03/1993)
Characteristics of a synchronous digital multiplex
equipment operating at 2048 kbit/s
[8] ITU-T G.742 (1988)
Second order digital multiplex equipment operating at
8448 kbit/s, and using positive justification
[9] ITU-T G.783 (10/2000)
Characteristics of synchronous digital hierarchy (SDH)
equipment functional blocks
[10] ITU-T G.812 (06/1998)
Timing requirements of slave clocks suitable for use as
node clocks in synchronization networks
[11] ITU-T G.813 (08/1996)
Timing characteristics of SDH equipment slave clocks
(SEC)
[12] ITU-T G.822 (11/1988)
Controlled slip rate objectives on an international digital
connection
[13] ITU-T G.823 (03/2000)
The control of jitter and wander within digital networks
which are based on the 2048 kbit/s hierarchy
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ACS8520 SETS
ADVANCED COMMUNICATIONS
FINAL
DATASHEET
Trademark Acknowledgements
[14] ITU-T G.824 (03/2000)
The control of jitter and wander within digital networks
which are based on the 1544 kbit/s hierarchy
[15] ITU-T G.825 (03/2000)
The control of jitter and wander within digital networks
which are based on the Synchronous Digital Hierarchy
(SDH)
[16] ITU-T K.41 (05/1998)
Resistibility of internal interfaces of telecommunication
centres to surge overvoltages
[17] Telcordia GR-253-CORE, Issue 3 (09/ 2000)
Synchronous Optical Network (SONET) Transport
Systems: Common Generic Criteria
Semtech and the Semtech S logo are registered
trademarks of Semtech Corporation.
ACCUNET® is a registered trademark of AT & T.
AMD is a registered trademark of Advanced Micro
Devices, Inc.
C-MAC is a registered trademark of
C-MAC MicroTechnology - a division of Solectron
Corporation.
ICT Flexacom is a registered trademark of ICT Electronics.
Motorola is a registered trademark of Motorola, Inc.
[18] Telcordia GR-499-CORE, Issue 2 (12/1998)
Transport Systems Generic Requirements (TSGR)
Common requirements
Telcordia is a registered trademark of Telcordia
Technologies.
[19] Telcordia GR-1244-CORE, Issue 2 (12/2000)
Clocks for the Synchronized Network: Common Generic
Criteria
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Revision Status/History
FINAL
The Revision Status of the datasheet, as shown in the
center of the datasheet header bar, may be DRAFT,
PRELIMINARY, or FINAL, and refers to the status of the
Device (not the datasheet) within the design cycle. DRAFT
status is used when the design is being realized but is not
yet physically available, and the datasheet content
reflects the intention of the design. The datasheet is
raised to PRELIMINARY status when initial prototype
devices are physically available, and the datasheet
content more accurately represents the realization of the
design. The datasheet is only raised to FINAL status after
DATASHEET
the device has been fully characterized, and the
datasheet content updated with measured, rather than
simulated parameter values.
This is a FINAL release (Revision 3.02) of the ACS8520
datasheet. Changes made for this document revision are
given in Table 43, together with a brief summary of
previous revisions. For specific changes between earlier
revisions, refer (where available) to those earlier
revisions. Always use the current version of the datasheet.
Table 43 Revision History
Revision
1.00/February 2002
Reference
See particular revision
1.01/February 2002
Description of changes
Initial datasheet and minor releases at Preliminary status. Refer to
particular release for the changes made for that release.
1.02/April 2002
1.03/April 2002
1.04/May 2002
1.05/September 2002
1.06/September 2002
2.00/January 2003
Major revision. First release at FINAL status and completely revised.
3.00/September 2003
Major revision.
3.01/October 2003
Minor revision
3.02/October 2005
Regs: 1D, 3C, 3D, 63, 64, 65 and 79
Register description updated.
Figures 23 and 24
Figures updated.
Page 21
“patent -pending” reference updated to “patented”.
Figure 5
Title change and note added to Figure.
Figure 30
Redrawn Figure.
Table 32
New row added for VDD5.
Figure 19 and pin 68 (Table 2)
References added such that A(1) = CLKE in serial mode.
Back page
Former US mailing address removed. (Mail now delivered to main
address).
Trademark Acknowledgements and
Revision Status/History
Sections updated.
Front page bullets, back page Ordering
Information and Abbreviations sections
References to availability of a lead (Pb)-free packaged version
(ACS8520T) added.
Revision 3.02/October 2005 © Semtech Corp.
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Notes
Revision 3.02/October 2005 © Semtech Corp.
FINAL
DATASHEET
Page 149
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ACS8520 SETS
ADVANCED COMMUNICATIONS
Ordering Information
FINAL
DATASHEET
Table 44 Parts List
Part Number
Description
ACS8520
SETS Synchronous Equipment Timing Source for Stratum 3/4E/4 and SMC Systems
ACS8520T
Lead (Pb)-free packaged version of ACS8520; RoHS and WEEE compliant.
Disclaimers
Life support- This product is not designed or intended for use in life support equipment, devices or systems, or other critical
applications. This product is not authorized or warranted by Semtech for such use.
Right to change- Semtech Corporation reserves the right to make changes, without notice, to this product. Customers are advised
to obtain the latest version of the relevant information before placing orders.
Compliance to relevant standards- Operation of this device is subject to the User’s implementation and design practices. It is the
responsibility of the User to ensure equipment using this device is compliant to any relevant standards.
Contacts
For Additional Information, contact the following:
Semtech Corporation Advanced Communications Products
E-mail:
[email protected]
[email protected]
Internet:
http://www.semtech.com
USA:
200 Flynn Road, Camarillo, CA 93012-8790
Tel: +1 805 498 2111,
Fax: +1 805 498 3804
FAR EAST: 11F, No. 46, Lane 11, Kuang Fu North Road, Taipei, R.O.C.
Tel: +886 2 2748 3380
Fax: +886 2 2748 3390
EUROPE:
Semtech Ltd., Units 2 and 3, Park Court, Premier Way,
Abbey Park Industrial Estate, Romsey, Hampshire, SO51 9DN
Tel: +44 (0)1794 527 600
Fax: +44 (0)1794 527 601
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CERTIFIED
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