Si5374 Data Sheet

Si5374
4-PLL A NY - F REQUENCY P RECISION C LOCK
M ULTIPLIER /J I T T E R A TTENUA TOR
Features






Highly-integrated, 4 PLL clock

multiplier/jitter attenuator
Four independent DSPLLs support
any-frequency synthesis and jitter
attenuation

8 inputs/8 outputs

Each DSPLL can generate any
frequency from 2 kHz to 808 MHz
from a 2 kHz to 710 MHz input

Ultra-low jitter clock outputs:
350 fs rms (12 kHz–20 MHz) and 
410 fs rms (50 kHz–80 MHz) typical
Meets ITU-T G.8251 and Telcordia
GR-253-CORE OC-192 jitter

specifications

Supports all ITU G.709 and any
custom FEC ratios (239/237,
255/238, 255/237, 255/236,
253/226)
Integrated loop filter with
programmable bandwidth
Simultaneous free-run and
synchronous operation
Automatic/manual hitless input clock
switching
Selectable output clock signal
format (LVPECL, LVDS, CML,
CMOS)
LOL and interrupt alarm outputs
Ordering Information:
See page 63.
I2C programmable
 Single 1.8 V ±5% or 2.5 V ±10%
operation with high PSRR on-chip
voltage regulator
 10x10 mm PBGA
Applications
High-density, any-port, any-protocol, 
any-frequency line cards

 ITU-T G.709 OTN custom FEC

 10/40/100G
 OC-48/192, STM-16/64


1/2/4/8/10G Fibre Channel
GbE/10 GbE Synchronous Ethernet
Carrier Ethernet, multi-service
switches and routers
MSPP, ROADM, P-OTS,
muxponders
Description
The Si5374 is a highly-integrated, 4-PLL, jitter-attenuating precision clock
multiplier for applications requiring sub-1 ps jitter performance. Each of the
DSPLL® clock multiplier engines accepts two input clocks ranging from 2 kHz to
710 MHz and generates two independent synchronous output clocks ranging
from 2 kHz to 808 MHz. The device provides virtually any frequency translation
combination across this operating range. For asynchronous, free-running clock
generation applications, the Si5374’s reference oscillator can be used as a clock
source for any of the four DSPLLs. The Si5374 input clock frequency and clock
multiplication ratio are programmable through an I2C interface. The Si5374 is
based on Silicon Laboratories’ third-generation DSPLL® technology, which
provides any-frequency synthesis and jitter attenuation in a highly-integrated
PLL solution that eliminates the need for external VCXO and loop filter
components. Each DSPLL loop bandwidth is digitally-programmable, providing
jitter performance optimization at the application level. The device operates from
a single 1.8 or 2.5 V supply with on-chip voltage regulators with excellent PSRR.
The Si5374 is ideal for providing clock multiplication and jitter attenuation in
high-port-count optical line cards requiring independent timing domains.
Rev. 1.1 1/14
Copyright © 2014 by Silicon Laboratories
Si5374
Si5374
Functional Block Diagram
PLL Bypass
Input Stage
Synthesis Stage
Output Stage
CKIN1P_A
÷ N31
CKIN1N_A
Input
Monitor
f3
CKIN2P_A
Hitless
Switch
CKIN2N_A
DSPLL®
fOSC
A
PLL Bypass
CKOUT1P_A
÷ NC1
CKOUT1N_A
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
÷ N2
CKOUT2P_A
PLL Bypass
CKOUT2N_A
PLL Bypass
CKOUT3P_B
÷ NC1
CKOUT3N_B
PLL Bypass
CKIN3P_B
÷ N31
CKIN3N_B
Input
Monitor
f3
CKIN4P_B
Hitless
Switch
CKIN4N_B
DSPLL®
fOSC
B
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
÷ N2
CKOUT4P_B
PLL Bypass
CKOUT4N_B
PLL Bypass
CKOUT5P_C
÷ NC1
CKOUT5N_C
PLL Bypass
CKIN5P_C
÷ N31
CKIN5N_C
Input
Monitor
f3
CKIN6P_C
Hitless
Switch
CKIN6N_C
DSPLL®
fOSC
C
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
÷ N2
CKOUT6P_C
PLL Bypass
CKOUT6N_C
PLL Bypass
CKOUT7P_D
÷ NC1
CKOUT7N_D
PLL Bypass
CKIN7P_D
÷ N31
CKIN7N_D
Input
Monitor
f3
CKIN8P_D
Hitless
Switch
CKIN8N_D
DSPLL®
D
÷ N2
RSTL_q
OSC_P/N
2
SDA LOL_q IRQ_q
PLL Bypass
High PSRR
Voltage Regulator
Status / Control
SCL
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
CS_CA_q
fOSC
Low Jitter
XO or Clock
Rev. 1.1
CKOUT8P_D
CKOUT8N_D
VDD_q
GND
Si5374
TABLE O F C ONTENTS
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3. Typical Phase Noise Plot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5. Si5374 Application Examples and Suggestions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
5.1. Schematic and PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.2. Thermal Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.3. SCL Leakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.4. RSTL_x Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.5. Reference Oscillator Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.6. Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.7. OSC_P and OSC_N Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6. Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7. Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
7.1. ICAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
8. Pin Descriptions: Si5374 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
9. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
10. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
11. Recommended PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
12. Top Markings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
12.1. Si5374 Top Marking (PBGA, Lead-Free) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
12.2. Top Marking Explanation (PBGA, Lead-Free) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
12.3. Si5374 Top Marking (PBGA, Lead-Finish) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
12.4. Top Marking Explanation (PBGA, Lead-Finish) . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
Rev. 1.1
3
Si5374
1. Electrical Specifications
Table 1. Recommended Operating Conditions
Parameter
Symbol
Ambient Temperature
TA
Supply Voltage during
Normal Operation
VDD
Test Condition
Min
Typ
Max
Unit
–40
25
85
°C
2.5 V Nominal
2.25
2.5
2.75
V
1.8 V Nominal
1.71
1.8
1.89
V
Note: All minimum and maximum specifications are guaranteed and apply across the recommended operating conditions.
Typical values apply at nominal supply voltages and an operating temperature of 25 ºC unless otherwise stated.
SIGNAL +
Differential I/Os VICM , VOCM
V
VISE , VOSE
SIGNAL –
(SIGNAL +) – (SIGNAL –)
Differential Peak-to-Peak Voltage
VID,VOD
VICM, VOCM
Single-Ended
Peak-to-Peak Voltage
t
SIGNAL +
VID = (SIGNAL+) – (SIGNAL–)
SIGNAL –
Figure 1. Differential Voltage Characteristics
80%
CKIN, CKOUT
20%
tF
tR
Figure 2. Rise/Fall Time Characteristics
4
Rev. 1.1
Si5374
Table 2. DC Characteristics
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
IDD
LVPECL Format
622.08 MHz Out
All CKOUTs Enabled
—
1000
1100
mA
LVPECL Format
622.08 MHz Out
4 CKOUTs Enabled
—
870
970
mA
CMOS Format
19.44 MHz Out
All CKOUTs Enabled
—
820
940
mA
CMOS Format
19.44 MHz Out
4 CKOUTs Enabled
—
780
880
mA
Disable Mode
—
660
—
mA
1.8 V ± 5%
0.9
—
1.4
V
2.5 V ± 10%
1
—
1.7
V
CKNRIN
Single-ended
20
40
60
k
Single-Ended Input
Voltage Swing
(See Absolute Specs)
VISE
fCKIN < 212.5 MHz
See Figure 1.
0.2
—
—
VPP
fCKIN > 212.5 MHz
See Figure 1.
0.25
—
—
VPP
Differential Input
Voltage Swing
(See Absolute Specs)
VID
fCKIN < 212.5 MHz
See Figure 1.
0.2
—
—
VPP
fCKIN > 212.5 MHz
See Figure 1.
0.25
—
—
VPP
CKOVCM
LVPECL 100  load
line-to-line
VDD –
1.42
—
VDD –1.25
V
CKOVD
LVPECL 100  load
line-to-line
1.1
—
1.9
VPP
Supply Current1
CKINn Input Pins2
Input Common Mode
Voltage (Input Threshold Voltage)
Input Resistance
VICM
Output Clocks (CKOUTn)3,4
Common Mode
Differential Output
Swing
Notes:
1. Current draw is independent of supply voltage.
2. No under- or overshoot is allowed.
3. LVPECL outputs require nominal VDD = 2.5 V.
4. LVPECL, CML, LVDS and low-swing LVDS measured with Fo = 622.08 MHz.
Rev. 1.1
5
Si5374
Table 2. DC Characteristics (Continued)
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Single Ended Output
Swing
CKOVSE
LVPECL 100  load
line-to-line
0.5
—
0.93
VPP
Differential Output
Voltage
CKOVD
CML 100  load
line-to-line
350
425
500
mVPP
CKOVCM
CML 100  load
line-to-line
—
VDD–0.36
—
V
CKOVD
LVDS
100  load line-to-line
500
700
900
mVPP
Low Swing LVDS
100  load line-to-line
350
425
500
mVPP
CKOVCM
LVDS 100 load
line-to-line
1.125
1.2
1.275
V
CKORD
CML, LVPECL, LVDS
—
200
—

Output Voltage Low
CKOVOLLH
CMOS
—
—
0.4
V
Output Voltage High
CKOVOHLH
VDD = 1.71 V
CMOS
0.8 x
VDD
—
—
V
CKOIO
ICMOS[1:0] = 11
VDD = 1.8 V
—
7.5
—
mA
ICMOS[1:0] = 10
VDD = 1.8 V
—
5.5
—
mA
ICMOS[1:0] = 01
VDD = 1.8 V
—
3.5
—
mA
ICMOS[1:0] = 00
VDD = 1.8 V
—
1.75
—
mA
ICMOS[1:0] = 11
VDD = 2.5 V
—
20
—
mA
ICMOS[1:0] = 10
VDD = 2.5 V
—
15
—
mA
ICMOS[1:0] = 01
VDD = 2.5 V
—
10
—
mA
ICMOS[1:0] = 00
VDD = 2.5 V
—
5
—
mA
Common Mode Output
Voltage
Differential Output
Voltage
Common Mode Output
Voltage
Differential Output
Resistance
Output Drive Current
(CMOS driving into
CKOVOL for output low
or CKOVOH for output
high. CKOUT+ and
CKOUT– shorted
externally)
Notes:
1. Current draw is independent of supply voltage.
2. No under- or overshoot is allowed.
3. LVPECL outputs require nominal VDD = 2.5 V.
4. LVPECL, CML, LVDS and low-swing LVDS measured with Fo = 622.08 MHz.
6
Rev. 1.1
Si5374
Table 2. DC Characteristics (Continued)
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
VDD = 1.71 V
—
—
0.5
V
VDD = 2.25 V
—
—
0.7
V
VDD = 1.89 V
1.4
—
—
V
VDD = 2.25 V
1.8
—
—
V
IO = 2 mA
VDD = 1.71 V
—
—
0.4
V
IO = 2 mA
VDD = 2.25 V
—
—
0.4
V
IO = –2 mA
VDD = 1.71 V
VDD –
0.4
—
—
V
IO = –2 mA
VDD = 2.25 V
VDD –
0.4
—
—
V
2-Level LVCMOS Input Pins
Input Voltage Low
Input Voltage High
VIL
VIH
LVCMOS Output Pins
Output Voltage Low
VOL
Output Voltage Low
Output Voltage High
Output Voltage High
VOH
Notes:
1. Current draw is independent of supply voltage.
2. No under- or overshoot is allowed.
3. LVPECL outputs require nominal VDD = 2.5 V.
4. LVPECL, CML, LVDS and low-swing LVDS measured with Fo = 622.08 MHz.
Rev. 1.1
7
Si5374
Table 3. AC Characteristics
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Single-Ended Reference Clock Input Pin OSC_P (OSC_N with cap to GND)1
OSC_P to OSC_N
Resistance
OSCRIN
RATE_REG = 0101 or
0110, ac coupled
—
100
—

Input Voltage Swing
OSCVPP
RATE_REG = 0101 or
0110, ac coupled
0.5
—
1.2
VPP
0.5
—
2.4
VPP
0.002
—
710
MHz
40
—
60
%
2
—
—
ns
—
—
11
ns
Differential Reference Clock Input Pins (OSC_P/OSC_N)1
Input Voltage Swing
OSCVPP
RATE_REG = 0101 or
0110, ac coupled
CKINn Input Pins
Input Frequency
CKNF
Input Duty Cycle
(Minimum Pulse
Width)
CKNDC
Input Rise/Fall Time
CKNTRF
Whichever is smaller
(i.e., the 40% / 60%
limitation applies only
to high-frequency
clocks)
20–80%
See Figure 2
CKOUTn Output Pins
Output Frequency
(Output not configured for CMOS or
Disabled)
CKOF
0.002
—
808
MHz
Maximum Output
Frequency in CMOS
Format
CKOF
—
—
212.5
MHz
Output Rise/Fall
(20–80 %) @
622.08 MHz output
CKOTRF
Output not configured for
CMOS or Disabled
See Figure 2
—
230
350
ps
Output Rise/Fall
(20–80%) @
212.5 MHz output
CKOTRF
CMOS Output
VDD = 1.71
CLOAD = 5 pF
—
—
8
ns
Output Rise/Fall
(20–80%) @
212.5 MHz output
CKOTRF
CMOS Output
VDD = 2.25
CLOAD = 5 pF
—
—
2
ns
Notes:
1. A crystal may not be used in place of an oscillator.
2. Input to output skew after an ICAL is not controlled and can be any value.
8
Rev. 1.1
Si5374
Table 3. AC Characteristics (Continued)
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Output Duty Cycle
Uncertainty @
622.08 MHz
Symbol
Test Condition
Min
Typ
Max
Unit
CKODC
100  Load
Line-to-Line
Measured at 50% Point
(differential)
—
—
±40
ps
LVCMOS Input Pins
Minimum Reset Pulse
Width
tRSTMN
1
—
—
µs
Reset to Microprocessor Access Ready
tREADY
—
—
10
ms
LVCMOS Output Pins
Rise/Fall Times
tRF
CLOAD = 20pf
See Figure 2
—
25
—
ns
LOSn Trigger Window
LOSTRIG
From last CKINn to 
Internal detection of LOSn
N3 ≠ 1
—
—
4.5 x N3
TCKIN
Time to Clear LOL
after LOS Cleared
tCLRLOL
LOS to LOL
Fold = Fnew
Stable OSC_P, OSC_N
reference
—
10
—
ms
Notes:
1. A crystal may not be used in place of an oscillator.
2. Input to output skew after an ICAL is not controlled and can be any value.
Rev. 1.1
9
Si5374
Table 3. AC Characteristics (Continued)
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Output Clock Skew
tSKEW
of CKOUTn to  of
CKOUT_m, CKOUTn
and CKOUT_m at same
frequency and signal
format
PHASEOFFSET = 0
CKOUT_ALWAYS_ON = 1
SQ_ICAL = 1
—
—
100
ps
Phase Change due to
Temperature Variation
tTEMP
Max phase changes from
–40 to +85 °C
—
300
500
ps
Device Skew2
Notes:
1. A crystal may not be used in place of an oscillator.
2. Input to output skew after an ICAL is not controlled and can be any value.
Table 4. Microprocessor Control
(VDD = 1.8 ± 5%, 2.5 ±10%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
I2C Bus Lines (SDA, SCL)
Input Voltage Low
VILI2C
—
—
0.25 x VDD
V
Input Voltage High
VIHI2C
0.7 x VDD
—
VDD
V
VDD = 1.8 V
0.1 x VDD
—
—
V
VDD = 2.5
0.05 x VDD
—
—
V
VDD = 1.8 V
IO = 3 mA
—
—
0.2 x VDD
V
VDD = 2.5
IO = 3 mA
—
—
0.4
V
Hysteresis of Schmitt
Trigger Inputs
Output Voltage Low
10
VHYSI2C
VOLI2C
Rev. 1.1
Si5374
Table 5. Performance Specifications
VDD = 1.8 V ±5% or 2.5 V ±10%, TA = –40 to 85 °C
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
tLOCKMP
Start of ICAL to of LOL,
FASTLOCK enabled
—
1
1.5
s
—
0.8
1.0
—
1.2
1.5
—
4.2
5.0
—
200
—
ps
—
0.05
0.1
dB
PLL Performance1
Lock Time2 Si5374B-A-xL3
Si5374C-A-xL
Settle Time2 Si5374B-A-xL
tSETTLE
Start of ICAL to FOUT within
5 ppm of final value
Si5374C-A-xL
Output Clock Phase Change
tP_STEP
After clock switch
f3  128 kHz
s
Closed Loop Jitter Peaking
JPK
Jitter Tolerance
JTOL
Jitter Frequency Loop
Bandwidth
5000/BW
—
—
ns
pk-pk
CKOPN
1 kHz Offset
—
–106
—
dBc/Hz
10 kHz Offset
—
–114
—
dBc/Hz
100 kHz Offset
—
–116
—
dBc/Hz
1 MHz Offset
—
–132
—
dBc/Hz
SPSPUR
Max spur @ n x F3
(n  1, n x F3 < 100 MHz)
—
–70
—
dBc
JGEN
fIN = fOUT = 622.08 MHz,
BW = 120 Hz
LVPECL output
12 kHz–20 MHz
—
350
410
fs rms
50 kHz–80 MHz
—
410
—
fs rms
Phase Noise
fout = 622.08 MHz
Spurious Noise
Jitter Generation
Notes:
1. fin = fout = 622.08 MHz; BW = 7 Hz; LVDS, OSC = .121.109 MHz.
2. Lock and settle time performance is dependent on the frequency plan and the OSC_P/OSC_N reference frequency
and LOCKT setting (see application note, "AN803: Lock and Settling Time Considerations for the Si5324/27/69/74
Any-Frequency Jitter Attenuating Clock ICs". Visit the Silicon Labs Technical Support web page at:
https://www.silabs.com/support/pages/contacttechnicalsupport.aspx to submit a technical support request regarding
the lock time of your frequency plan.
3. LOCKT = 3.3 ms.
Rev. 1.1
11
Si5374
Table 6. Thermal Characteristics1,2
Parameter
Symbol
Test Condition
Maximum Junction
Temperature
Min
Typ
Max
Unit
—
125
—
°C
Thermal Resistance
Junction to Ambient
JA
Still Air
Air Flow 1 m/s
Air Flow 2 m/s
Air Flow 3 m/s
—
—
—
—
16
14
13
12
—
—
—
—
°C/W
Thermal Resistance
Junction to Case
JC
Still Air
—
3.4
—
°C/W
Notes:
1. In most circumstances the Si5374 does not require special thermal management. A system level thermal analysis is
strongly recommend. Contact Silicon Labs applications for further details if required.
2. Thermal characteristic for the 80-pin Si5374 on an 8-layer PCB.
Table 7. Absolute Maximum Ratings
Parameter
Symbol
Value
Unit
DC Supply Voltage
VDD
–0.5 to 2.8
V
LVCMOS Input Voltage
VDIG
–0.3 to (VDD + 0.3)
V
CLKINnP/N_q
CKNVIN
0 to VDD
V
OSC_P, OSC_N Voltage Limits
OSCVIN
0 to 1.2
V
Operating Junction Temperature
TJCT
–55 to 150
°C
Storage Temperature Range
TSTG
–55 to 150
°C
2
kV
ESD MM Tolerance; All pins except
CKINnP/N_q
200
V
ESD HBM Tolerance (100 pF, 1.5 k);
CKINnP/N_q
700
V
ESD MM Tolerance; CKINnP/N_q
125
V
ESD HBM Tolerance (100 pF, 1.5 k); All pins
except CKINnP/N-q
Latch-Up Tolerance
JESD78 Compliant
Note: Permanent device damage may occur if the absolute maximum ratings are exceeded. Functional operation should be
restricted to the conditions as specified in the operation sections of this data sheet. Exposure to absolute maximum
rating conditions for extended periods of time may affect device reliability.
12
Rev. 1.1
Si5374
2. Typical Application Schematic
4-Port 10G Line Card
with SyncE and IEEE1588
Independent Port Timing
FPGA
10G
10G
PHY
10G
IEEE PHY
PHY
1588
Slave
1588
Recovered
Clocks
Ethernet
Datapath
4
10G
10G
10G PHY
PHY
10G
PHY
PHY
4
Rx
SyncE
Recovered
Clocks
Tx
Tx
Tx
4
Tx
Si5374
SyncE_1
1588_1
DSPLL
SyncE_2
1588_2
Port
Independent
Timing
(SyncE or 1588)
DSPLL
SyncE_3
1588_3
DSPLL
SyncE_4
1588_4
DSPLL
Rev. 1.1
13
Si5374
3. Typical Phase Noise Plot
19.44 MHz input
 698.8123 MHz OTU4 output
 334 fs RMS jitter (12 kHz to 20 MHz)

Figure 3. Typical Phase Noise Plot
14
Rev. 1.1
Si5374
4. Functional Description
PLL Bypass
Input Stage
Synthesis Stage
Output Stage
CKIN1P_A
÷ N31
CKIN1N_A
Input
Monitor
f3
CKIN2P_A
Hitless
Switch
CKIN2N_A
DSPLL®
fOSC
A
PLL Bypass
CKOUT1P_A
÷ NC1
CKOUT1N_A
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
PLL Bypass
÷ N2
CKOUT2P_A
CKOUT2N_A
PLL Bypass
CKIN3P_B
÷ N31
CKIN3N_B
Input
Monitor
f3
CKIN4P_B
Hitless
Switch
CKIN4N_B
DSPLL®
fOSC
B
PLL Bypass
CKOUT3P_B
÷ NC1
CKOUT3N_B
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
÷ N2
CKOUT4P_B
PLL Bypass
CKOUT4N_B
PLL Bypass
CKOUT5P_C
÷ NC1
CKOUT5N_C
PLL Bypass
CKIN5P_C
÷ N31
CKIN5N_C
Input
Monitor
f3
CKIN6P_C
Hitless
Switch
CKIN6N_C
DSPLL®
fOSC
C
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
÷ N2
CKOUT6P_C
PLL Bypass
CKOUT6N_C
PLL Bypass
CKOUT7P_D
÷ NC1
CKOUT7N_D
PLL Bypass
CKIN7P_D
÷ N31
CKIN7N_D
Input
Monitor
f3
CKIN8P_D
Hitless
Switch
CKIN8N_D
DSPLL®
D
fOSC
÷ NC1_HS
÷ NC2
÷ N32
Internal
Osc
÷ N2
RSTL_q
High PSRR
Voltage Regulator
Status / Control
CS_CA_q
PLL Bypass
CKOUT8P_D
CKOUT8N_D
VDD_q
GND
OSC_P/N
SCL
SDA LOL_q IRQ_q
Low Jitter
XO or Clock
Figure 4. Functional Block Diagram
Rev. 1.1
15
Si5374
The Si5374 is a highly integrated jitter-attenuating clock
multiplier that integrates four fully independent DSPLLs
and provides ultra-low jitter generation with less than
410 fs RMS. Configuration and control of the Si5374 is
mainly handled through the I2C interface. The device
accepts clock inputs ranging from 2 kHz to 710 MHz
and generates independent, synchronous clock outputs
ranging from 2 kHz to 808 MHz for each DSPLL.
Virtually any frequency translation (M/N) combination
across its operating range is supported. The Si5374
supports a digitally programmable loop bandwidth that
can range from 4 to 525 Hz requiring no external loop
filter components. An external single-ended or
differential reference clock or XO is required for the
device to enable ultra-low jitter generation and jitter
attenuation.
The device monitors each input clock for loss-of-signal
(LOS) and provides a LOS alarm when missing pulses
on any of the input clocks are detected. The device
monitors the lock status of each DSPLL and provides a
Loss-of-Lock (LOL) alarm when the DSPLL is unlocked.
The lock detect algorithm continuously monitors the
phase of the selected input clock in relation to the phase
of the feedback clock. See application note, "AN803:
Lock and Settling Time Considerations for the
Si5324/27/69/74 Any-Frequency Jitter Attenuating
Clock ICs."
16
The Si5374 provides a holdover capability that allows
the device to continue generation of a stable output
clock when the input reference is lost. The reference
oscillator can be internally routed into CKIN2_q, so freerunning clock generation is supported for each DSPLL
offering simultaneous synchronous and asynchronous
operation.
The output drivers are configurable to support common
signal formats, such as LVPECL, LVDS, CML, and
CMOS loads. If the CMOS signal format is selected,
each differential output buffer generates two in-phase
CMOS clocks at the same frequency. For system-level
debugging, a DSPLL bypass mode drives the clock
output directly from the selected input clock, bypassing
the internal DSPLL.
Silicon Laboratories offers a PC-based software utility,
Si537xDSPLLsim that can be used to determine valid
frequency plans and loop bandwidth settings to simplify
device setup. Si537xDSPLLsim provides the optimum
input, output, and feedback divider values for a given
input frequency and clock multiplication ratio that
minimizes phase noise. This utility can be downloaded
from
http://www.silabs.com/timing.
For
further
assistance, refer to the Si53xx Any-Frequency Precision
Clocks Family Reference Manual.
Rev. 1.1
Si5374
5. Si5374 Application Examples and
Suggestions
5.1. Schematic and PCB Layout
For a typical application schematic and PCB layout, see
the Si537x-EVB Evaluation Board User's Guide, which
can be downloaded from www.silabs.com/timing.
In order to preserve the ultra low jitter of the Si5374 in
applications where the four different DSPLL's are each
operating at different frequency, special care and
attention must be paid to the PCB layout. The following
is a list of rules that should be observed:
1. The four Vdd supplies should be isolated from one
another with four ferrite beads. They should be
separately bypassed with capacitors that are located
very close to the Si5374 device.
2. Use a solid and undisturbed ground plane for the
Si5374 and all of the clock input and output return
paths.
3. For applications that wish to logically connect the
four RESET signals, do not tie them together
underneath the BGA package. Instead connect them
outside of the BGA footprint.
4. As much as is possible, do not route clock input and
output signals underneath the BGA package. The
clock output signals should go directly outwards from
the BGA footprint.
5. Avoid placing the OSC_P and OSC_N signals on the
same layer as the clock outputs. Add grounded
guard traces surrounding the OSC_P and OSC_N
signals.
6. Where possible, place the CKOUT and CKIN signals
on separate PCB layers with a ground layer between
them. The use of ground guard traces between all
clock inputs and outputs is recommended.
For more information, see the Si537x-EVB Evaluation
Board User's Guide and Appendix I of the Si53xx
Reference Manual, Rev 0.5 or higher.
5.2. Thermal Considerations
The Si5374 dissipates a significant amount of heat and
it is important to take this into consideration when
designing the Si5374 operating environment. Among
other issues, high die temperatures can result in
increased jitter and decreased long term reliability. It is
therefore recommended that one or more of the
following occur:
1. Use a heat sink - A heat sink example is Aavid part
number 375324B00035G.
2. Use a Vdd voltage of 1.8 V.
3. Limit the ambient temperature to significantly less
that 85 °C.
4. Implement very good air flow.
5.3. SCL Leakage
When selecting pull up resistors for the two I2C signals,
note that there is an internal pull down resistor of 18 k
from the SCL pin to ground. This comment does not
apply to the SDA pin.
5.4. RSTL_x Pins
It is recommended that the four RSTL_x pins (RSTL_A,
RSTL_B, RSTL_C and RSTL_D) be logically connected
together such that all four DSPLLs are either in or out of
reset mode. When a DSPLL is in reset mode, its VCO
will not be locked to any signal and may drift across its
operating range. If a drifting VCO has a frequency
similar to that of an operating VCO, there could be
some crosstalk between the two VCOs. To avoid this
from occurring during device initialization, DSPLLsim
loads each DSPLL with default Free Run frequency
plans with VCO values apart from one another. If the
four RSTL_x pins are directly connected to one another,
the connections should not be made directly underneath
the BGA package. Instead, the connections should be
made outside the package footprint.
5.5. Reference Oscillator Selection
Care should be taken during the selection of the
external oscillator that is connected to the OSC_P and
OSC_N pins. There is no jitter attenuation from the OSC
reference inputs to the output; so, to achieve low output
jitter, a low-jitter reference OSC must be used. Also, the
output drift during holdover will be the same as the drift
of the OSC reference. For example, a Stratum 3
application will require an OSC reference source that
has Stratum 3 stability (though Stratum 3 accuracy is
not required).
The OSC frequency can be any value from 109 to
125.5 MHz. See the RATE_REG (reg 2) description.
Alternately, for applications with less demanding jitter
requirements, the OSC frequency can be in the range
from 37 to 41 MHz. For applications that use Free Run
mode, the freedom to use any OSC frequency within
these bands can be used to select an OSC frequency
that has an integer relationship to the desired output
frequency, which will make it easier to find a highperformance frequency plan.
If Free Run is not being used, an OSC frequency that is
not integer-related to the output frequency is preferred.
A recommended choice for an external oscillator is the
Silicon Labs 530EB121M109DG, which is a 2.5 V,
LVPECL device with a temperature stability of 20 ppm.
It was used to take the typical phase noise plot on
page 14. For more details and a more complete
discussion of these topics, see the Si53xx Reference
Manual.
The very low loop BW of the Si5374 means that it can
be susceptible to OSC_P/OSC_N reference sources
Rev. 1.1
17
Si5374
that have high wander. Experience has shown that in
spite of having low jitter, some MEMs oscillators have
high wander, and these devices should be avoided.
Silicon Labs does not recommend using MEMS based
oscillators as the Si5374 frequency reference. Contact
Silicon Labs for details.
LOSx_INT
in
Sticky
out
5.6. Alarms
To assist in the programming of the IRQ_n pins, refer to
the below diagram of the Si5374 alarm structure.
LOSX_FLG
LOSX_MSK
Write 0
to clear
INT_POL
LOS1_INT
in
Sticky
out
LOS1_MSK
Write 0
to clear
LOS2_INT
in
Sticky
out
in
Sticky
E
out
in
Sticky
out
in
Sticky
Write 0
to clear
FOS2_FLG
FOS2_MSK
Write 0
to clear
LOL_INT
FOS1_FLG
FOS1_MSK
Write 0
to clear
FOS2_INT
IRQ_PIN
LOS2_FLG
LOS2_MSK
Write 0
to clear
FOS1_INT
LOS1_FLG
out
LOL_FLG
LOL_MSK
Figure 5. Si5374 Alarm Structure
18
Rev. 1.1
IRQ_n
Si5374
5.7. OSC_P and OSC_N Connection
Figures 6, 7, and 8 show examples of connecting
various OSC reference sources to the OSC_P and
OSC_N pins. A crystal may not be used in place of an
external oscillator.
Si5374
0.01 F
LVDS, LVPECL, CML, etc.
0.01 F
OSC-P
OSC-N
1.2 V
100 
2.5 k
0.6 V
Figure 6. Differential OSC Reference Input Example for Si5374
Si5374
0.01 F
LVDS, LVPECL, CML, etc.
0.01 F
OSC-P
OSC-N
1.2 V
100 
2.5 k
0.6 V
Figure 7. Single-Ended OSC Reference Input Example for Si5374
2.5 V
2.5 V
CMOS
XO
150 
82 
Si5374
10 nF
OSC-P
1.2 V
E5
150 
10 nF
E6
OSC-N
0.6 V
Figure 8. Single-Ended, 2.5 V, CMOS XO Connection
Rev. 1.1
19
Si5374
6. Register Map
The Si5374 has four identical register maps for each DSPLL. Each DSPLL has a unique I2C address enabling
independent control and device configuration. The I2C address is 11010 [A1] [A0] for the entire device. Each
corresponding DSPLL [A1] [A0] address is fixed as below.
[A1] [A0]
DSPLLA:
0
0
DSPLLB:
0
1
DSPLLC:
1
0
DSPLLD:
1
1
Note: The Si5374 register map is similar, but not identical, to the Si5324 device.
All register bits that are not defined in this map should always be written with the specific reset values. Writing to
these bits with values other than the specified reset values may result in undefined device behavior. Registers not
listed, such as Register 64, should never be written to.
Table 8. Si5374 Registers
Reg.
D7
0
D6
D5
D4
D3
D2
D1
FREE_RU
CKOUT_
N
ALWAYS_ON
BYPASS_REG
1
CK_PRIOR2[1:0]
2
BWSEL_REG[3:0]
3
CKSEL_REG[1:0]
4
AUTOSEL_REG[1:0]
5
ICMOS[1:0]
CK_PRIOR1[1:0]
RATE_REG [3:0]
DHOLD
SQ_ICAL
HIST_DEL[4:0]
6
SFOUT2_REG[2:0}
SFOUT1_REG[2:0]
7
8
FOSREFSEL[2:0]
HLOG_2[1:0]
HLOG_1[1:0]
9
HIST_AVG[4:0]
10
DSBL2_ REG
DSBL1_ REG
11
19
PD_CK2
FOS_EN
FOS_THR[1:0]
20
21
D0
VALTIME[1:0]
Write 0
Write 0
LOCKT[2:0]
Write 0
Write 0
22
PD_CK1
CK_ACTV_
POL
LOL_PIN
IRQ_PIN
CK1_ACTV_PIN
CKSEL_PIN
LOL_POL
INT_POL
23
LOS2_MSK
LOS1_MSK
LOSX_MSK
24
FOS2_MSK
FOS1_MSK
LOL_MSK
25
N1_HS[2:0]
31
32
20
NC1_LS[19:16]
NC1_LS[15:8]
Rev. 1.1
Si5374
Table 8. Si5374 Registers (Continued)
Reg.
D7
D6
D5
33
D4
D3
D2
D1
NC1_LS[7:0]
34
NC2_LS[19:16]
35
NC2_LS[15:8]
36
NC2_LS[7:0]
40
N2_HS[2:0]
N2_LS[19:16]
41
N2_LS[15:8]
42
N2_LS[7:0]
43
N31[18:16]
44
N31[15:8]
45
N31[7:0]
46
N32[18:16]
47
N32[15:8]
48
N32[7:0]
55
CLKIN2RATE[2:0]
CLKIN1RATE[2:0]
128
129
130
DIGHOLD
VALID
131
132
FOS2_FLG
134
CK2_ACTV_REG
CK1_ACTV_REG
LOS2_INT
LOS1_INT
LOSX_INT
FOS2_INT
FOS1_INT
LOL_INT
LOS2_FLG
LOS1_FLG
LOSX_FLG
FOS1_FLG
LOL_FLG
PARTNUM_RO[11:4]
135
136
PARTNUM_RO[3:0]
RST_REG
REVID_RO[3:0]
ICAL
137
FASTLOCK
138
139
D0
LOS2_EN[0: LOS1_EN[0:
0]
0]
142
INDEPENDENTSKEW1[7:0]
143
INDEPENDENTSKEW2[7:0]
Rev. 1.1
LOS2_EN [1:1]
LOS1_EN [1:1]
FOS2_EN
FOS1_EN
21
Si5374
7. Register Descriptions
Register 0.
Bit
D7
D5
D4
D3
D2
FREE_RUN CKOUT_ALWAYS_ON
Name
Type
D6
R
R/W
R/W
D1
D0
BYPASS_REG
R
R
R
R/W
R
Reset value = 0001 0100
Bit
Name
Function
7
Reserved
Reserved.
6
FREE_RUN
Free Run.
Internal to the device, route XA/XB to CKIN2. This allows the DSPLL to lock to
its XA-XB reference to support free-running clock generation.
0: Disable
1: Enable
5
CKOUT_ALWAYS_ON
CKOUT Always On.
This will bypass the SQ_ICAL function. Output will be available even if SQ_ICAL is on and ICAL is not complete or successful. See Table 9 on page 56.
0: Squelch output until device is calibrated (ICAL).
1: Provide an output.
Notes:
1. The frequency may be significantly off until the device is calibrated.
2. Must be set to 1 to control output to output skew.
4:2
Reserved
1
BYPASS_REG
Reserved.
Bypass Register.
This bit enables or disables PLL bypass mode. Use only when the device is in
digital hold or before the first ICAL. Bypass mode does not support CMOS
clock outputs.
0: Normal operation
1: Bypass mode. Selected input clock is connected to CKOUT buffers, bypassing PLL.
0
22
Reserved
Reserved.
Rev. 1.1
Si5374
Register 1.
Bit
D7
D6
D5
D4
Name
R
Type
D3
D2
D1
D0
CK_PRIOR2 [1:0]
CK_PRIOR1 [1:0]
R/W
R/W
Reset value = 1110 0100
Bit
Name
7:4
Reserved
3:2
Function
CK_PRIOR2 [1:0] 2nd Priority Input Clock.
Selects which of the input clocks will be 2nd priority in the autoselection state
machine.
00: CKIN1 is 2nd priority.
01: CKIN2 is 2nd priority.
10: Reserved
11: Reserved
1:0
CK_PRIOR1 [1:0] 1st Priority Input Clock.
Selects which of the input clocks will be 1st priority in the autoselection state
machine.
00: CKIN1 is 1st priority.
01: CKIN2 is 1st priority.
10: Reserved
11: Reserved
Rev. 1.1
23
Si5374
Register 2.
Bit
D7
D6
D5
D4
D3
D2
D1
Name
BWSEL_REG [3:0]
RATE_REG[3:0]
Type
R/W
R/W
D0
Reset value = 0100 0010
Bit
7:4
Name
Function
BWSEL_REG [3:0] BWSEL_REG.
Selects nominal f3dB bandwidth for PLL. See Si53xDSPLLsim for settings. After
BWSEL_REG is written with a new value, an ICAL is required for the change to
take effect.
3:0
RATE_REG [3:0]
RATE Setting for Oscillator.
An external oscillator or other clock source must be used. It is not possible to
use just a crystal.
Setting
0101
0110
Others: Reserved
24
Minimum
37
109
Rev. 1.1
Recommended
40
121.109
Maximum
41
125.5
Units
MHz
MHz
Si5374
Register 3.
Bit
D7
D6
D5
D4
Name
CKSEL_REG[1:0]
DHOLD
SQ_ICAL
Type
R/W
R/W
R/W
D3
D2
D1
D0
R
R
R
R
Reset value = 0000 0101
Bit
7:6
Name
Function
CKSEL_REG [1:0] CKSEL_REG.
If the device is operating in register-based manual clock selection mode
(AUTOSEL_REG = 00), and CKSEL_PIN = 0, then these bits select which input
clock will be the active input clock. If CKSEL_PIN = 1 and AUTOSEL_REG = 00, the
CS_CA input pin continues to control clock selection and CKSEL_REG is of no consequence.
00: CKIN_1 selected.
01: CKIN_2 selected.
10: Reserved
11: Reserved
5
DHOLD
DHOLD.
Forces the device into digital hold. This bit overrides all other manual and automatic
clock selection controls.
0: Normal operation.
1: Force digital hold mode. Overrides all other settings and ignores the quality of the
input clocks.
4
SQ_ICAL
SQ_ICAL.
This bit determines if the output clocks will remain enabled or be squelched (disabled) during an internal calibration. See Table 9 on page 56.
0: Output clocks enabled during ICAL.
1: Output clocks disabled during ICAL.
3:0
Reserved
Rev. 1.1
25
Si5374
Register 4.
Bit
D7
D6
Name
AUTOSEL_REG [1:0]
Type
R/W
D5
D4
D3
D2
D1
D0
HIST_DEL [4:0]
R
R/W
Reset value = 0001 0010
Bit
Name
Function
7:6
AUTOSEL_REG [1:0]
AUTOSEL_REG [1:0].
Selects input clock selection control method.
00: Manual (either register or pin controlled, see CKSEL_PIN)
01: Automatic non-revertive
10: Automatic revertive
11: Reserved
5
Reserved
4:0
HIST_DEL [4:0]
HIST_DEL [4:0].
Selects amount of delay to be used in generating the history information used
for Digital Hold.
Register 5.
Bit
D7
D6
Name
ICMOS [1:0]
Type
R/W
D5
D4
D3
D2
D1
D0
R
R
R
R
R
R
Reset value = 1110 1101
Bit
Name
7:6
ICMOS [1:0]
Function
ICMOS [1:0].
When the output buffer is set to CMOS mode, these bits determine the output buffer drive
strength. The first number below refers to 2.5 V operation; the second to 1.8 V operation.
These values assume CKOUT+ is tied to CKOUT-.
00: 5 mA/1.75 mA
01: 10 mA/3.5 mA
10: 15 mA/5.5 mA
11: 20 mA/7.5 mA
5:0
26
Reserved
Rev. 1.1
Si5374
Register 6.
Bit
D7
D6
Name
Type
R
D5
D4
D3
D2
D1
SFOUT2_REG [2:0]
SFOUT1_REG [2:0]
R/W
R/W
R
D0
Reset value = 0010 1101
Bit
Name
7:6
Reserved
5:3
SFOUT2_
REG [2:0]
SFOUT2_REG [2:0].
SFOUT1_
REG [2:0]
SFOUT1_REG [2:0].
2:0
Function
Controls output signal format and disable for CKOUT2 output buffer.
000: Reserved
001: Disable CKOUT2
010: CMOS (Bypass mode not supported)
011: Low swing LVDS
100: Reserved
101: LVPECL (not available when VDD = 1.8 V)
110: CML
111: LVDS
Controls output signal format and disable for CKOUT1 output buffer.
000: Reserved
001: Disable CKOUT1
010: CMOS (Bypass mode not supported)
011: Low swing LVDS
100: Reserved
101: LVPECL (not available when VDD = 1.8 V)
110: CML
111: LVDS
Rev. 1.1
27
Si5374
Register 7.
Bit
D7
D6
D5
D4
D3
D1
D0
FOSREFSEL [2:0]
Name
Type
D2
R
R
R
R
R
R/W
Reset value = 0010 1010
Bit
Name
7:3
Reserved
2:0
28
Function
FOSREFSEL FOSREFSEL [2:0].
[2:0]
Selects which input clock is used as the reference frequency for Frequency offset (FOS)
monitoring.
000: OSC (External reference)
001: CKIN1
010: CKIN2
011: Reserved
100: Reserved
101: Reserved
110: Reserved
111: Reserved
Rev. 1.1
Si5374
Register 8.
Bit
D7
D6
D5
D4
Name
HLOG_2[1:0]
HLOG_1[1:0]
Type
R/W
R/W
D3
D2
D1
D0
R
R
R
R
Reset value = 0000 0000
Bit
7:6
Name
Function
HLOG_2 [1:0] HLOG_2 [1:0].
00: Normal operation
01: Holds CKOUT2 output at static logic 0.
Entrance and exit from this state will occur without glitches or runt pulses.
10:Holds CKOUT2 output at static logic 1.
Entrance and exit from this state will occur without glitches or runt pulses.
11: Reserved
5:4
HLOG_1 [1:0] HLOG_1 [1:0].
00: Normal operation
01: Holds CKOUT1 output at static logic 0.
Entrance and exit from this state will occur without glitches or runt pulses.
10: Holds CKOUT1 output at static logic 1.
Entrance and exit from this state will occur without glitches or runt pulses.
11: Reserved
3:0
Reserved
Register 9.
Bit
D7
D6
D5
Name
HIST_AVG [4:0]
Type
R/W
D4
D3
D2
D1
D0
R
R
R
Reset value = 1100 0000
Bit
7:3
Name
Function
HIST_AVG [4:0] HIST_AVG [4:0].
Selects amount of averaging time to be used in generating frequency history information for Digital Hold.
2:0
Reserved
Rev. 1.1
29
Si5374
Register 10.
Bit
D7
D6
D5
D4
Name
Type
R
R
R
D3
D2
DSBL2_REG
DSBL1_REG
R/W
R/W
R
D1
D0
R
R
Reset value = 0000 0000
Bit
Name
7:4
Reserved
3
Function
DSBL2_REG DSBL2_REG.
This bit controls the powerdown of the CKOUT2 output buffer. If disable mode is
selected, the NC2 output divider is also powered down.
0: CKOUT2 enabled
1: CKOUT2 disabled
2
DSBL1_REG DSBL1_REG.
This bit controls the powerdown of the CKOUT1 output buffer. If disable mode is
selected, the NC1 output divider is also powered down.
0: CKOUT1 enabled
1: CKOUT1 disabled
1:0
Reserved
Register 11.
Bit
D7
D6
D5
D4
D3
D2
Name
Type
R
R
R
R
R
R
Reset value = 0100 0000
Bit
Name
7:2
Reserved
1
PD_CK2
Function
PD_CK2.
This bit controls the powerdown of the CKIN2 input buffer.
0: CKIN2 enabled
1: CKIN2 disabled
0
PD_CK1
PD_CK1.
This bit controls the powerdown of the CKIN1 input buffer.
0: CKIN1 enabled
1: CKIN1 disabled
30
Rev. 1.1
D1
D0
PD_CK2
PD_CK1
R/W
R/W
Si5374
Register 19.
Bit
D7
D6
D5
D4
D3
D2
D1
Name
FOS_EN
FOS_THR [1:0]
VALTIME [1:0]
LOCKT [2:0]
Type
R/W
R/W
R/W
R/W
D0
Reset value = 0010 1100
Bit
Name
7:5
FOS_EN
Function
FOS_EN.
Frequency Offset Enable globally disables FOS. See the individual FOS enables (FOSX_EN, register 139).
0: FOS disable
1: FOS enabled by FOSx_EN
6:5
FOS_THR [1:0] FOS_THR [1:0].
Frequency Offset at which FOS is declared:
00: ± 11 to 12 ppm (Stratum 3/3E compliant, with a Stratum 3/3E used for REFCLK.
01: ± 48 to 49 ppm SONET Minimum Clock (SMC) with SMC used for REFCLK.
10: ± 30 ppm (SONET Minimum Clock (SMC), with a Stratum 3/3E used for REFCLK.
11: ± 200 ppm
4:3
VALTIME [1:0] VALTIME [1:0].
Sets amount of time for input clock to be valid before the associated alarm is removed.
00: 2 ms
01: 100 ms
10: 200 ms
11: 13 seconds
2:0
LOCKT [2:0]
LOCKT [2:0].
Sets retrigger interval for one shot monitoring phase detector output. One shot is triggered by phase slip in DSPLL. To minimize lock time during an ICAL, a LOCKT value of
001 is recommended. Refer to the Family Reference Manual and application note,
"AN803: Lock and Settling Time Considerations for the Si5324/27/69/74 Any-Frequency
Jitter Attenuating Clock ICs", for more details.
000: 106 ms
001: 53 ms
010: 26.5 ms
011: 13.3 ms
100: 6.6 ms
101: 3.3 ms
110: 1.66 ms
111: 0.833 ms
Rev. 1.1
31
Si5374
Register 20.
Bit
D7
D6
D5
D4
Name
Type
R
R
R
R
D3
D2
D1
D0
Write 0
Write 0
LOL_PIN
IRQ_PIN
W
W
R/W
R/W
Reset value = 0011 1110
Bit
Name
7:4
Reserved
3:2
Write 0
1
LOL_PIN
Function
Write to zero.
LOL_PIN.
The LOL_INT status bit can be reflected on the LOL output pin.
0: LOL output pin tristated
1: LOL_INT status reflected to output pin
0
IRQ_PIN
IRQ_PIN.
Reflects interrupt status on the IRQ output pin.
0: Output is disabled.
1: Output is enabled.
32
Rev. 1.1
Si5374
Register 21.
Bit
D7
D6
Name
Write 0
Write 0
Type
W
W
D5
R
D4
R
D3
R
D2
R
D1
D0
CK1_ACTV_PIN
CKSEL_ PIN
R/W
R/W
Reset value = 1111 1111
Bit
Name
7:6
Write 0
5:2
Reserved
1
Function
Write zero.
CK1_ACTV_PIN CK1_ACTV_PIN.
The CK1_ACTV_REG status bit can be reflected to the CS_CA output pin using the
CK1_ACTV_PIN enable function. CK1_ACTV_PIN is of consequence only when pin
controlled clock selection is being used.
0: CS_CA output pin tristated.
1: Clock Active status reflected to output pin.
0
CKSEL_PIN
CKSEL_PIN.
If manual clock selection is used, clock selection can be controlled via the
CKSEL_REG[1:0] register bits or the CS_CA input pin. This bit is only active when
AUTOSEL_REG = Manual.
0: CS_CA pin ignored. CKSEL_REG[1:0] register bits control clock selection.
1: CS_CA input pin controls clock selection.
Rev. 1.1
33
Si5374
Register 22.
Bit
D7
D6
D5
D4
D2
CK_ACTV_POL
Name
Type
D3
R
R
R
R
R/W
R
D1
D0
LOL_POL
INT_POL
R/W
R/W
Reset value = 1101 1111
Bit
Name
7:4
Reserved
3
CK_ACTV_ POL
Function
CK_ACTV_POL.
Sets the active polarity for the CS_CA signals when reflected on an output pin.
0: Active low
1: Active high
2
Reserved
1
LOL_POL
LOL_POL.
Sets the active polarity for the LOL status when reflected on an output pin.
0: Active low
1: Active high
0
INT_POL
INT_POL.
Sets the active polarity for the interrupt status when reflected on the INT_C1B output pin.
0: Active low
1: Active high
34
Rev. 1.1
Si5374
Register 23.
Bit
D7
D6
D5
D4
D3
Name
Type
R
R
R
R
R
D2
D1
D0
LOS2_ MSK
LOS1_ MSK
LOSX_ MSK
R/W
R/W
R/W
Reset value = 0001 1111
Bit
Name
7:3
Reserved
2
LOS2_MSK
Function
LOS2_MSK.
Determines if a LOS on CKIN2 (LOS2_FLG) is used in the generation of an interrupt.
Writes to this register do not change the value held in the LOS2_FLG register.
0: LOS2 alarm triggers active interrupt on IRQ output (if IRQ=1).
1: LOS2_FLG ignored in generating interrupt output.
1
LOS1_MSK
LOS1_MSK.
Determines if a LOS on CKIN1 (LOS1_FLG) is used in the generation of an interrupt.
Writes to this register do not change the value held in the LOS1_FLG register.
0: LOS1 alarm triggers active interrupt on IRQ output (if IRQ=1).
1: LOS1_FLG ignored in generating interrupt output.
0
LOSX_MSK
LOSX_MSK.
Determines if a LOS on OSC (LOSX_FLG) is used in the generation of an interrupt.
Writes to this register do not change the value held in the LOSX_FLG register.
0: LOSX alarm triggers active interrupt on IRQ output (if IRQ=1).
1: LOSX_FLG ignored in generating interrupt output.
Rev. 1.1
35
Si5374
Register 24.
Bit
D7
D6
D5
D4
D3
Name
Type
R
R
R
R
R
D2
D1
D0
FOS2_MSK
FOS1_MSK
LOL_MSK
R/W
R/W
R/W
Reset value = 0011 1111
Bit
Name
7:3
Reserved
2
FOS2_MSK
Function
FOS2_MSK.
Determines if the FOS2_FLG is used in the generation of an interrupt. Writes to this register do not change the value held in the FOS2_FLG register.
0: FOS2 alarm triggers active interrupt on IRQ output (if IRQ_PIN=1).
1: FOS2_FLG ignored in generating interrupt output.
1
FOS1_MSK
FOS1_MSK.
Determines if the FOS1_FLG is used in the generation of an interrupt. Writes to this register do not change the value held in the FOS1_FLG register.
0: FOS1 alarm triggers active interrupt on IRQ output (if IRQ_PIN=1).
1: FOS1_FLG ignored in generating interrupt output.
0
LOL_MSK
LOL_MSK.
Determines if the LOL_FLG is used in the generation of an interrupt. Writes to this register do not change the value held in the LOL_FLG register.
0: LOL alarm triggers active interrupt on IRQ output (if IRQ_PIN=1).
1: LOL_FLG ignored in generating interrupt output.
36
Rev. 1.1
Si5374
Register 25.
Bit
D7
D6
Name
N1_HS [2:0]
Type
R/W
D5
D4
D3
D2
D1
D0
R
R
R
R
R
Reset value = 0010 0000
Bit
Name
7:5
N1_HS [2:0]
Function
N1_HS [2:0].
Sets value for N1 high speed divider which drives NCn_LS (n = 1 to 2) low-speed divider.
000: N1 = 4
001: N1 = 5
010: N1 = 6
011: N1 = 7
100: N1 = 8
101: N1 = 9
110: N1 = 10
111: N1 = 11
4:0
Reserved
Register 31.
Bit
D7
D6
D5
D4
D3
D1
D0
NC1_LS [19:16]
Name
Type
D2
R
R
R
R
R/W
Reset value = 0000 0000
Bit
Name
7:4
Reserved
3:0
NC1_LS
[19:16]
Function
NC1_LS [19:16].
Sets value for NC1 low-speed divider, which drives CKOUT1 output. Must be 0 or odd.
00000000000000000000 = 1
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111=220
Valid divider values=[1, 2, 4, 6, ..., 220]
Rev. 1.1
37
Si5374
Register 32.
Bit
D7
D6
D5
D4
D3
Name
NC1_LS [15:8]
Type
R/W
D2
D1
D0
Reset value = 0000 0000
Bit
Name
7:0
NC1_LS
[15:8]
Function
NC1_LS [15:8].
Sets value for NC1 low-speed divider, which drives CKOUT1 output. Must be 0 or odd.
00000000000000000000 = 1
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111=220
Valid divider values=[1, 2, 4, 6, ..., 220]
Register 33.
Bit
D7
D6
D5
D4
D3
Name
NC1_LS [7:0]
Type
R/W
D2
D1
D0
Reset value = 0011 0001
38
Bit
Name
7:0
NC1_LS
[19:0]
Function
NC1_LS [7:0].
Sets value for NC1 low-speed divider, which drives CKOUT1 output. Must be 0 or odd.
00000000000000000000 = 1
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111=220
Valid divider values=[1, 2, 4, 6, ..., 220]
Rev. 1.1
Si5374
Register 34.
Bit
D7
D6
D5
D4
D3
D2
D1
D0
NC2_LS [19:16]
Name
R
Type
R
R
R
R/W
Reset value = 0000 0000
Bit
Name
7:4
Reserved
3:0
NC2_LS
[19:16]
Function
NC2_LS [19:16].
Sets value for NC2 low-speed divider, which drives CKOUT2 output. Must be 0 or odd.
00000000000000000000=1
00000000000000000001=2
00000000000000000011=4
00000000000000000101=6
...
11111111111111111111=220
Valid divider values=[1, 2, 4, 6, ..., 220]
Register 35.
Bit
D7
D6
D5
D4
D3
Name
NC2_LS [15:8]
Type
R/W
D2
D1
D0
Reset value = 0000 0000
Bit
7:0
Name
Function
NC2_LS [15:8] NC2_LS [15:8].
Sets value for NC2 low-speed divider, which drives CKOUT2 output. Must be 0 or odd.
00000000000000000000 = 1
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111=220
Valid divider values=[1, 2, 4, 6, ..., 220]
Rev. 1.1
39
Si5374
Register 36.
Bit
D7
D6
D5
D4
D3
Name
NC2_LS [7:0]
Type
R/W
D2
D1
D0
Reset value = 0011 0001
Bit
7:0
Name
Function
NC2_LS [7:0] NC2_LS [7:0].
Sets value for NC2 low-speed divider, which drives CKOUT2 output. Must be 0 or odd.
00000000000000000000 = 1
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111 = 220
Valid divider values = [1, 2, 4, 6, ..., 220]
40
Rev. 1.1
Si5374
Register 40.
Bit
D7
D6
Name
N2_HS [2:0]
Type
R/W
D5
D4
D3
D2
D1
D0
N2_LS [19:16]
R
R/W
Reset value = 1100 0000
Bit
Name
7:5
N2_HS [2:0]
Function
N2_HS [2:0].
Sets value for N2 high speed divider which drives N2LS low-speed divider.
000: 4
001: 5
010: 6
011: 7
100: 8
101: 9
110: 10
111: 11
4
Reserved
3:0
N2_LS [19:16]
N2_LS [19:16].
Sets value for N2 low-speed divider, which drives phase detector.
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111 = 220
Valid divider values = [2, 4, 6, ..., 220]
Rev. 1.1
41
Si5374
Register 41.
Bit
D7
D6
D5
D4
D3
Name
N2_LS [15:8]
Type
R/W
D2
D1
D0
D1
D0
Reset value = 0000 0000
Bit
7:0
Name
Function
N2_LS [15:8] N2_LS [15:8].
Sets value for N2 low-speed divider, which drives phase detector.
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111 = 220
Valid divider values = [2, 4, 6, ..., 220]
Register 42.
Bit
D7
D6
D5
D4
D3
Name
N2_LS [7:0]
Type
R/W
D2
Reset value = 1111 1001
Bit
Name
7:0
N2_LS [7:0]
Function
N2_LS [7:0].
Sets value for N2 low-speed divider, which drives phase detector.
00000000000000000001 = 2
00000000000000000011 = 4
00000000000000000101 = 6
...
11111111111111111111 = 220
Valid divider values = [2, 4, 6, ..., 220]
42
Rev. 1.1
Si5374
Register 43.
Bit
D7
D6
D5
D4
D3
D2
D1
D0
N31 [18:16]
Name
R
Type
R
R
R
R
R/W
Reset value = 0000 0000
Bit
Name
7:3
Reserved
2:0
N31 [18:16]
Function
N31 [18:16].
Sets value for input divider for CKIN1.
0000000000000000000 = 1
0000000000000000001 = 2
0000000000000000010 = 3
...
1111111111111111111 = 219
Valid divider values = [1, 2, 3, ..., 219]
Register 44.
Bit
D7
D6
D5
D4
D3
Name
N31_[15:8]
Type
R/W
D2
D1
D0
Reset value = 0000 0000
Bit
Name
7:0
N31_[15:8]
Function
N31_[15:8].
Sets value for input divider for CKIN1.
0000000000000000000 = 1
0000000000000000001 = 2
0000000000000000010 = 3
...
1111111111111111111 = 219
Valid divider values = [1, 2, 3, ..., 219]
Rev. 1.1
43
Si5374
Register 45.
Bit
D7
D6
D5
D4
D3
Name
N31_[7:0]
Type
R/W
D2
D1
D0
D2
D1
D0
Reset value = 0000 1001
Bit
Name
7:0
N31_[7:0
Function
N31_[7:0].
Sets value for input divider for CKIN1.
0000000000000000000 = 1
0000000000000000001 = 2
0000000000000000010 = 3
...
1111111111111111111 = 219
Valid divider values = [1, 2, 3, ..., 219]
Register 46.
Bit
D7
D6
D5
D4
D3
N32_[18:16]
Name
Type
R
R
R
R
R
Reset value = 0000 0000
Bit
Name
7:3
Reserved
2:0
N32_[18:16]
Function
N32_[18:16].
Sets value for input divider for CKIN1.
0000000000000000000 = 1
0000000000000000001 = 2
0000000000000000010 = 3
...
1111111111111111111 = 219
Valid divider values = [1, 2, 3, ..., 219]
44
Rev. 1.1
R/W
Si5374
Register 47.
Bit
D7
D6
D5
D4
D3
Name
N32_[15:8]
Type
R/W
D2
D1
D0
D2
D1
D0
Reset value = 0000 0000
Bit
Name
7:0
N32_[15:8]
Function
N32_[15:8].
Sets value for input divider for CKIN2.
0000000000000000000 = 1
0000000000000000001 = 2
0000000000000000010 = 3
...
1111111111111111111 = 219
Valid divider values = [1, 2, 3, ..., 219]
Register 48.
Bit
D7
D6
D5
D4
D3
Name
N32_[7:0]
Type
R/W
Reset value = 0000 1001
Bit
Name
7:0
N32_[7:0]
Function
N32_[7:0].
Sets value for input divider for CKIN2.
0000000000000000000 = 1
0000000000000000001 = 2
0000000000000000010 = 3
...
1111111111111111111 = 219
Valid divider values = [1, 2, 3, ..., 219]
Rev. 1.1
45
Si5374
Register 55.
Bit
D7
D6
Name
Type
R
D5
D4
D3
D2
CLKIN2RATE[2:0]
CLKIN1RATE[2:0]
R/W
R/W
R
Reset value = 0000 0000
Bit
Name
7:6
Reserved
5:3
CLKIN2RATE[2:0]
Function
CLKIN2RATE_[2:0].
CKINn frequency selection for FOS alarm monitoring.
000: 10–27 MHz
001: 25–54 MHz
002: 50–105 MHz
003: 95–215 MHz
004: 190–435 MHz
005: 375–710 MHz
006: Reserved
007: Reserved
2:0
CLKIN1RATE [2:0] CLKIN1RATE[2:0].
CKINn frequency selection for FOS alarm monitoring.
000: 10–27 MHz
001: 25–54 MHz
002: 50–105 MHz
003: 95–215 MHz
004: 190–435 MHz
005: 375–710 MHz
006: Reserved
007: Reserved
46
D1
Rev. 1.1
D0
Si5374
Register 128.
Bit
D7
D6
D5
D4
D3
D2
D1
CK2_ACTV_REG CK1_ACTV_REG
Name
Type
D0
R
R
R
R
R
R
R
R
Reset value = 0010 0000
Bit
Name
Function
7:2
Reserved
1
CK2_ACTV_REG
CK2_ACTV_REG.
Indicates if CKIN2 is currently the active clock for the DSPLL input.
0: CKIN2 is not the active input clock. Either it is not selected or LOS2_INT is 1.
1: CKIN2 is the active input clock.
0
CK1_ACTV_REG
CK1_ACTV_REG.
Indicates if CKIN1 is currently the active clock for the DSPLL input.
0: CKIN1 is not the active input clock. Either it is not selected or LOS1_INT is 1.
1: CKIN1 is the active input clock.
Register 129.
Bit
D7
D6
D5
D4
D3
Name
Type
R
R
R
R
D2
D1
D0
LOS2_INT
LOS1_INT
LOSX_INT
R
R
R
R
Reset value = 0000 0110
Bit
Name
7:3
Reserved
2
LOS2_INT
Function
LOS2_INT.
Indicates the LOS status on CKIN2.
0: Normal operation.
1: Internal loss-of-signal alarm on CKIN2 input.
1
LOS1_INT
LOS1_INT.
Indicates the LOS status on CKIN1.
0: Normal operation.
1: Internal loss-of-signal alarm on CKIN1 input.
0
LOSX_INT
LOSX_INT.
Indicates the LOS status of the external reference on the OSC pins.
0: Normal operation.
1: Internal loss-of-signal alarm on OSC reference clock input.
Rev. 1.1
47
Si5374
Register 130.
Bit
D7
D5
D4
D3
DIGHOLDVALID
Name
Type
D6
R
R
D2
D1
FOS2_INT FOS1_INT
R
R
R
R
R
D0
LOL_INT
R
Reset value = 0000 0001
Bit
Name
7
Reserved
6
DIGHOLDVALID
Function
Digital Hold Valid.
Indicates if the digital hold circuit has enough samples of a valid clock to meet digital hold specifications.
0: Indicates digital hold history registers have not been filled. The digital hold output frequency may not meet specifications.
1: Indicates digital hold history registers have been filled. The digital hold output
frequency is valid.
5:3
Reserved
2
FOS2_INT
CKIN2 Frequency Offset Status.
0: Normal operation.
1: Internal frequency offset alarm on CKIN2 input.
1
FOS1_INT
CKIN1 Frequency Offset Status.
0: Normal operation.
1: Internal frequency offset alarm on CKIN1 input.
0
LOL_INT
PLL Loss of Lock Status.
0: PLL locked.
1: PLL unlocked.
48
Rev. 1.1
Si5374
Register 131.
Bit
D7
D6
D5
D4
D3
D1
D0
LOS2_FLG LOS1_FLG LOSX_FLG
Name
Type
D2
R
R
R
R
R
R/W
R/W
R/W
Reset value = 0001 1111
Bit
Name
7:3
Reserved
2
LOS2_FLG
Function
CKIN2 Loss-of-Signal Flag.
0: Normal operation.
1: Held version of LOS2_INT. Generates active output interrupt if output interrupt pin is
enabled (IRQ_PIN = 1) and if not masked by LOS2_MSK bit. Flag cleared by writing 0 to
this bit.
1
LOS1_FLG
CKIN1 Loss-of-Signal Flag.
0: Normal operation
1: Held version of LOS1_INT. Generates active output interrupt if output interrupt pin is
enabled (IRQ_PIN = 1) and if not masked by LOS1_MSK bit. Flag cleared by writing 0 to
this bit.
0
LOSX_FLG
External Reference (signal on pins XA/XB) Loss-of-Signal Flag.
0: Normal operation
1: Held version of LOSX_INT. Generates active output interrupt if output interrupt pin is
enabled (IRQ_PIN = 1) and if not masked by LOSX_MSK bit. Flag cleared by writing 0 to
this bit.
Rev. 1.1
49
Si5374
Register 132.
Bit
D7
D6
D5
D4
D2
FOS2_FLG FOS1_FLG
Name
Type
D3
R
R
R
R
R/W
R/W
D1
D0
LOL_FLG
R/W
R
Reset value = 0000 0010
Bit
Name
7:4
Reserved
3
FOS2_FLG
Function
CLKIN_2 Frequency Offset Flag.
0: Normal operation.
1: Held version of FOS2_INT. Generates active output interrupt if output interrupt pin is
enabled (IRQ_PIN = 1) and if not masked by FOS2_MSK bit. Flag cleared by writing 0 to
this bit.
2
FOS1_FLG
CLKIN_1 Frequency Offset Flag.
0: Normal operation
1: Held version of FOS1_INT. Generates active output interrupt if output interrupt pin is
enabled (IRQ_PIN = 1) and if not masked by FOS1_MSK bit. Flag cleared by writing 0 to
this bit.
1
LOL_FLG
PLL Loss of Lock Flag.
0: PLL locked
1: Held version of LOL_INT. Generates active output interrupt if output interrupt pin is
enabled (IRQ_PIN = 1) and if not masked by LOL_MSK bit. Flag cleared by writing 0 to
this bit.
0
50
Reserved
Rev. 1.1
Si5374
Register 134.
Bit
D7
D6
D5
D4
D3
Name
PARTNUM_RO [11:4]
Type
R
D2
D1
D0
D2
D1
D0
Reset value = 0000 0001
Bit
Name
Function
7:0
PARTNUM_RO [11:0]
Device ID (1 of 2).
0000 0100 1010: Si5374
Others: Reserved
Register 135.
Bit
D7
D6
D5
D4
D3
Name
PARTNUM_RO [3:0]
REVID_RO [3:0]
Type
R
R
Reset value = 1010 0010
Bit
Name
7:4
PARTNUM_RO [11:0]
Function
Device ID (2 of 2).
0000 0100 1010: Si5374
Others: Reserved
3:0
REVID_RO [3:0]
Indicates Device Revision Level.
0010: Revision C
Others: Reserved.
Rev. 1.1
51
Si5374
Register 136.
Bit
D7
D6
Name
RST_REG
ICAL
Type
R/W
R/W
D5
D4
D3
D2
D1
D0
R
R
R
R
R
R
Reset value = 0000 0000
Bit
Name
7
RST_REG
Function
Internal Reset (Same as Pin Reset).
Note: The I2C port may not be accessed until 10 ms after RST_REG is asserted.
0: Normal operation.
1: Reset all internal logic. Outputs disabled or tristated during reset.
6
ICAL
Start Internal Calibration Sequence.
For proper operation, the device must go through an internal calibration sequence.
ICAL is a self-clearing bit. Writing a one to this location initiates an ICAL. The calibration is complete once the LOL alarm goes low. A valid stable clock (within 100 ppm)
must be present to begin ICAL.
Note: Any divider, CLKINn_RATE or BWSEL_REG changes require an ICAL to take
effect.
0: Normal operation.
1: Writing a "1" initiates internal self-calibration. Upon completion of internal self-calibration, LOL will go low.
5:0
Reserved
Register 137.
Bit
D7
D6
D5
D4
D3
D2
D1
FASTLOCK
Name
Type
D0
R
R
R
R
R
R
R
R/W
Reset value = 0000 0000
Bit
Name
7:1
Reserved
0
FASTLOCK
Function
Do not modify.
This bit must be set to 1 to enable FASTLOCK.
This improves initial lock time by dynamically changing the loop bandwidth during
PLL lock acquisition.
52
Rev. 1.1
Si5374
Register 138.
Bit
D7
D6
D5
D4
D3
D2
Name
Type
R
R
R
R
R
R
D1
D0
LOS2_EN [1:1]
LOS1_EN [1:1]
R/W
R/W
Reset value = 0000 1111
Bit
Name
7:2
Reserved
1
LOS2_EN [1:0]
MSB
Function
Enable CKIN2 LOS Monitoring on the Specified Input (2 of 2).
Note: LOS2_EN is split between two registers.
00: Disable LOS monitoring.
01: Reserved.
10: Enable LOSA monitoring.
11: Enable LOS monitoring.
LOSA is a slower and less sensitive version of LOS. See the Family Reference Manual
for details.
0
LOS1_EN [1:0]
MSB
Enable CKIN1 LOS Monitoring on the Specified Input (1 of 2).
Note: LOS1_EN is split between two registers.
00: Disable LOS monitoring.
01: Reserved.
10: Enable LOSA monitoring.
11: Enable LOS monitoring.
LOSA is a slower and less sensitive version of LOS. See the Family Reference Manual
for details.
Rev. 1.1
53
Si5374
Register 139.
Bit
D7
D6
Name
Type
R
R
D5
D4
LOS2_EN [0:0]
LOS1_EN [0:0]
R/W
R/W
D3
R
D2
D1
D0
FOS2_EN
FOS1_EN
R/W
R/W
R
Reset value = 1111 1111
Bit
Name
7:6
Reserved
Function
5
LOS2_EN [1:0] Enable CKIN2 LOS Monitoring on the Specified Input (2 of 2).
LSB
Note: LOS2_EN is split between two registers.
00: Disable LOS monitoring.
01: Reserved.
10: Enable LOSA monitoring.
11: Enable LOS monitoring.
LOSA is a slower and less sensitive version of LOS. See the family reference manual
for details.
4
LOS_EN [1:0]
LSB
Enable CKIN1 LOS Monitoring on the Specified Input (1 of 2).
Note: LOS1_EN is split between two registers.
00: Disable LOS monitoring.
01: Reserved.
10: Enable LOSA monitoring.
11: Enable LOS monitoring.
LOSA is a slower and less sensitive version of LOS. See the family reference manual
for details.
3:2
Reserved
1
FOS2_EN
Enables FOS on a Per Channel Basis.
0: Disable FOS monitoring.
1: Enable FOS monitoring.
0
FOS1_EN
Enables FOS on a Per Channel Basis.
0: Disable FOS monitoring.
1: Enable FOS monitoring.
54
Rev. 1.1
Si5374
Register 142.
Bit
D7
D6
D5
D4
D3
D2
Name
INDEPENDENTSKEW1 [7:0]
Type
R/W
D1
D0
Reset value = 0000 0000
Bit
Name
7:0
INDEPENDENTSKEW1 [7:0]
Function
INDEPENDENTSKEW1.
Eight-bit field that represents a 2s complement of the phase offset in
terms of clocks from the high speed output divider. Default = 0.
Register 143.
Bit
D7
D6
D5
D4
D3
D2
Name
INDEPENDENTSKEW2 [7:0]
Type
R/W
D1
D0
Reset value = 0000 0000
Bit
7:0
Name
Function
INDEPENDENTSKEW2 [7:0] INDEPENDENTSKEW2.
8 bit field that represents a twos complement of the phase offset in terms
of clocks from the high speed output divider. Default = 0.
Rev. 1.1
55
Si5374
7.1. ICAL
The device registers must be configured for the device operation. After device configuration, a calibration
procedure must be performed once a stable clock is applied to the selected CKINn input. The calibration process is
triggered by writing a “1” to bit D6 in register 136. See the Family Reference Manual for details. In addition, after a
successful calibration operation, changing any of the registers indicated in Table 9 requires that a calibration be
performed again by the same procedure (writing a “1” to bit D6 in register 136).
Table 9. ICAL-Sensitive Registers
56
Address
Register
0
BYPASS_REG
0
CKOUT_ALWAYS_ON
1
CK_PRIOR1
1
CK_PRIOR2
2
BSWEL_REG
2
RATE_REG
4
HIST_DEL
5
ICMOS
7
FOSREFSEL
9
HIST_AVG
10
DSBL1_REG
10
DSBL2_REG
11
PD_CK1
11
PD_CK2
19
FOS_EN
19
FOS_THR
19
LOCKT
19
VALTIME
25
N1_HS
31
NC1_LS
34
NC2_LS
40
N2_HS
40
N2_LS
43
N31
46
N32
55
CLKIN1RATE
55
CLKIN2RATE
Rev. 1.1
Si5374
Table 10. CKOUT_ALWAYS_ON and SQ_ICAL Truth Table
CKOUT_ALWAYS_ON
SQ_ICAL
Results
0
0
CKOUT OFF until after the first ICAL
0
1
CKOUT OFF until after the first successful
ICAL (i.e., when LOL is low)
1
0
CKOUT always ON, including during an ICAL
1
1
CKOUT always ON, including during an ICAL.
Use these settings to preserve output-to-output
skew
Rev. 1.1
57
Si5374
8. Pin Descriptions: Si5374
9
8
7
6
5
4
3
2
CKOUT1P_B
GND
VDD_B
CS_CA_B
CKOUT2P_A
CKOUT2N_A
GND
CKOUT1N_A
CKOUT1N_B
GND
CKIN1P_B
CKIN1N_B
VDD_A
IRQ_A
GND
GND
CKOUT1P_A
B
GND
GND
CKIN2P_B
CKIN2N_B
LOL_B
VDD_A
CKIN2P_A
CKIN1P_A
VDD_A
C
CKOUT2N_B
IRQ_B
VDD_B
RSTL_B
VDD_B
RSTL_A
CKIN2N_A
CKIN1N_A
CS_CA_A
D
CKOUT2P_B
LOL_C
VDD_C
OSC_N
OSC_P
GND
VDD_D
LOL_A
CS_CA_C
CKIN1N_C
CKIN2N_C
RSTL_C
VDD_C
RSTL_D
VDD_D
IRQ_D
CKOUT2N_D
F
VDD_C
CKIN1P_C
CKIN2P_C
SDA
SCL
CKIN2N_D
CKIN2P_D
GND
GND
G
GND
GND
GND
IRQ_C
LOL_D
CKIN1N_D
CKIN1P_D
GND
CKOUT1N_D
H
CKOUT1P_C
CKOUT1N_C
CKOUT2N_C
CKOUT2P_C
CS_CA_D
VDD_D
GND
CKOUT1P_D
GND
Bottom View
Figure 9. Si5374 Pin Configuration (Bottom View)
58
Rev. 1.1
1
A
CKOUT2P_D
E
J
Si5374
Table 11. Si5374 Pin Descriptions
Pin #
Pin Name
I/O
Signal
Level
Description
D4
D6
F6
F4
RSTL_A
RSTL_B
RSTL_C
RSTL_D
I
LVCMOS
External Reset.
Active low input that performs external hardware reset of all four
DSPLLs. Resets all internal logic to a known state and forces the
device registers to their default value. Clock outputs are tri-stated
during reset. The part must be programmed after a reset or
power-on to get a clock output. This pin has a weak pull-up.
B4
D8
H6
F2
IRQ_A
IRQ_B
IRQ_C
IRQ_D
O
LVCMOS
DSPLLq Interrupt Indicator.
This pin functions as a device interrupt output. The interrupt output, IRQ_PINn must be set to 1. The pin functions as a maskable
interrupt output with active polarity controlled by the IRQ_POLn
register bit.
0 = CKINn present
1 = LOS (FOS) on CKINn
The active polarity is controlled by CK_BAD_POL. If no function
is selected, the pin tri-states.
C1, C4, B5
VDD_A
A7, D5, D7
VDD_B
E7, F5, G9
VDD_C
E3, F3, J3
VDD_D
E5
E6
OSC_P
OSC_N
VDD
Supply
Supply.
The device operates from a 1.8 or 2.5 V supply. A 0.1 µF bypass
capacitive is required for every VDD_9 pin. Bypass capacitors
should be associated with the following VDD_q pins:
0.1 µF per VDD pin.
Four 1.0 µF should also be placed as close to each VDD domain
as is practical. See recommended layout.
I
Analog
External OSC.
An external low jitter reference clock should be connected to
these pins. See the any-frequency precision clocks family reference manual for oscillator selection details.
Note: Internal register names are indicated by italics, e.g., IRQ_PIN. See Si5374 Register Map.
Rev. 1.1
59
Si5374
Table 11. Si5374 Pin Descriptions (Continued)
Pin #
Pin Name
I/O
Signal
Level
B2
A3
B3
E4
C8
A8
B8
C9
H7
J7
H8
H9
G1
H2
J2
G2
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
Supply
C2
D2
C3
D3
CKIN1P_A
CKIN1N_A
CKIN2P_A
CKIN2N_A
I
B7
B6
C7
C6
CKIN1P_B
CKIN1N_B
CKIN2P_B
CKIN2N_B
G8
F8
G7
F7
CKIN1P_C
CKIN1N_C
CKIN2P_C
CKIN2N_C
H3
H4
G3
G4
CKIN1P_D
CKIN1N_D
CKIN2P_D
CKIN2N_D
Description
Ground for each DSPLLq.
Must be connected to system ground. Minimize the ground path
impedance for optimal performance of this device. See
recommended layout.
Multi
Clock Inputs for DSPLLq.
Differential input clocks. This input can also be driven with a single-ended signal.
Note: Internal register names are indicated by italics, e.g., IRQ_PIN. See Si5374 Register Map.
60
Rev. 1.1
Si5374
Table 11. Si5374 Pin Descriptions (Continued)
Pin #
Pin Name
I/O
Signal
Level
Description
E2
C5
E8
H5
LOL_A
LOL_B
LOL_C
LOL_D
O
LVCMOS
DSPLLq Loss of Lock Indicator.
These pins function as the active high PLL loss of lock indicator if
the LOL_PIN register bit is set to 1.
0 = PLL locked.
1 = PLL unlocked.
If LOL_PINn = 0, this pin will tri-state. Active polarity is controlled
by the LOL_POLn bit. The PLL lock status will always be
reflected in the LOL_INTn read only register bit (see application
note, "AN803: Lock and Settling Time Considerations for the
Si5324/27/69/74 Any-Frequency Jitter Attenuating Clock ICs).
D1
A6
F9
J4
CS_CA_A
CS_CA_B
CS_CA_C
CS_CA_D
I/O
LVCMOS DSPLLq Input Clock Select/Active Clock Indicator.
Input: In manual clock selection mode, this pin functions as the
manual input clock selector if the CKSEL_PIN is set to 1.
0 = Select CKIN1
1 = Select CKIN2
If CKSEL_PIN = 0, the CKSEL_REG register bit controls this
function and this input tristates. If configured for input, must be
tied high or low.
Output: In automatic clock selection mode, this pin indicates
which of the two input clocks is currently the active clock. If
alarms exist on both clocks, CK_ACTV will indicate the last active
clock that was used before entering the digital hold state. The
CK_ACTV_PIN register bit must be set to 1 to reflect the active
clock status to the CK_ACTV output pin.
0 = CKIN1 active input clock
1 = CKIN2 active input clock
If CK_ACTV_PIN = 0, this pin will tristate. The CK_ACTV status
will always be reflected in the CK_ACTV_REG read only register
bit.
G5
SCL
I
LVCMOS
I2C Serial Clock.
This pin functions as the serial clock input.
This pin has a weak pull-down.
G6
SDA
I/O
LVCMOS
I2C Serial Data.
I2C pin functions as the bi-directional serial data port.
Note: Internal register names are indicated by italics, e.g., IRQ_PIN. See Si5374 Register Map.
Rev. 1.1
61
Si5374
Table 11. Si5374 Pin Descriptions (Continued)
Pin #
Pin Name
I/O
Signal
Level
Description
B1
A2
A5
A4
CKOUT1P_A
CKOUT1N_A
CKOUT2P_A
CKOUT2N_A
O
Multi
A9
B9
E9
D9
CKOUT1P_B
CKOUT1N_B
CKOUT2P_B
CKOUT2N_B
Output Clock for DSPLLq.
Differential output clocks. Output signal format is selected by
SFOUT_REG register bits. Output is differential for LVPECL,
LVDS, and CML compatible modes. For CMOS format, both output pins drive in phase single-ended clock outputs at the same
frequency.
J9
J8
J5
J6
CKOUT1P_C
CKOUT1N_C
CKOUT2P_C
CKOUT2N_C
J1
H1
E1
F1
CKOUT1P_D
CKOUT1N_D
CKOUT2P_D
CKOUT2N_D
Note: Internal register names are indicated by italics, e.g., IRQ_PIN. See Si5374 Register Map.
62
Rev. 1.1
Si5374
9. Ordering Guide
Ordering Part
Number
Input/Output
Clocks
PLL
Bandwidth
Range
Package
RoHS6
Pb-Free
Temperature
Range
Si5374B-A-GL1
8/8
4 to 525 Hz
10x10 mm
80-PBGA
Yes
–40 to 85 °C
Si5374B-A-BL1
8/8
4 to 525 Hz
10x10 mm
80-PBGA
No
–40 to 85 °C
Si5374C-A-GL2
8/8
4 to 525 Hz
10x10 mm
80-PBGA
Yes
–40 to 85 °C
Si5374C-A-BL2
8/8
4 to 525 Hz
10x10 mm
80-PBGA
No
–40 to 85 °C
Si5374-EVB
Evaluation Board
Notes:
1. These two OPNs are recommended for all new designs. Refer to application note, “AN803: Lock and Settling Time
Considerations for Si5324/27/69/74 Any Frequency Jitter Attenuating Clock ICs” for more information.
2. These two OPNs are intended for use in legacy designs in which the Si5374 device must retain the original lock time
behavior as described in AN803 and Product Bulletin (PB-1312191): “Si5324, Si5327, Si5369, Si5374 Loss-of-Lock
(LOL) Time Behavior: New Applications Note and Ordering Options”.
Rev. 1.1
63
Si5374
10. Package Outline
Figure 10 illustrates the package details for the Si5374. Table 12 lists the values for the dimensions shown in the
illustration.
Figure 10. 80-Pin Plastic Ball Grid Array (PBGA)
Table 12. Package Dimensions
Symbol
Min
Nom
Max
Min
Nom
A
1.22
1.39
1.56
E1
8.00 BSC
A1
0.40
0.50
0.60
e
1.00 BSC
A2
0.32
0.36
0.40
aaa
0.10
A3
0.46
0.53
0.60
bbb
0.10
b
0.50
0.60
0.70
ccc
0.12
D
10.00 BSC
ddd
0.15
E
10.00 BSC
eee
0.08
D1
8.00 BSC
Max
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to JEDEC outline MO-192.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body
Components.
64
Rev. 1.1
Si5374
11. Recommended PCB Layout
Figure 11. PBGA Card Layout
Table 13. Layout Dimensions
Symbol
MIN
NOM
MAX
X
0.40
0.45
0.50
C1
8.00
C2
8.00
E1
1.00
E2
1.00
Notes:
General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing is per the ANSI Y14.5M-1994 specification.
3. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design
4. All metal pads are to be non-solder mask defined (NSMD). Clearance between the
solder mask and the metal pad is to be 60 µm minimum, all the way around the pad.
Stencil Design
5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should
be used to assure good solder paste release.
6. The stencil thickness should be 0.125 mm (5 mils).
7. The ratio of stencil aperture to land pad size should be 1:1.
Card Assembly
8. A No-Clean, Type-3 solder paste is recommended.
9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification
for Small Body Components.
Rev. 1.1
65
Si5374
12. Top Markings
12.1. Si5374 Top Marking (PBGA, Lead-Free)

12.2. Top Marking Explanation (PBGA, Lead-Free)
Mark Method:
Laser
Logo Size:
6.1 x 2.2 mm
Center-Justified
Font Size:
0.80 mm
Right-Justified
Line 1 Marking:
Device Part Number
Si5374B-A-GL, Pb-free
Line 2 Marking:
YY = Year
WW = Work Week
Assigned by the Assembly House.
Corresponds to the year and work
week of the mold date.
TTTTTT = Mfg Code
Manufacturing Code from the
Assembly Purchase Order form.
Pin 1 Identifier
Circle = 0.75 mm Diameter
Lower-Left Justified
“e1” Lead-Free Finish Symbol
(Pb-Free BGA Balls)
Circle = 1.4 mm Diameter
Center-Justified
Country of Origin
TW
Line 3 Marking:
66
Rev. 1.1
Si5374
12.3. Si5374 Top Marking (PBGA, Lead-Finish)

12.4. Top Marking Explanation (PBGA, Lead-Finish)
Mark Method:
Laser
Logo Size:
6.1 x 2.2 mm
Center-Justified
Font Size:
0.80 mm
Right-Justified
Line 1 Marking:
Device Part Number
Si5374B-A-BL, Pb finish
Line 2 Marking:
YY = Year
WW = Work Week
Assigned by the Assembly House.
Corresponds to the year and work
week of the mold date.
TTTTTT = Mfg Code
Manufacturing Code from the
Assembly Purchase Order form.
Pin 1 Identifier
Circle = 0.75 mm Diameter
Lower-Left Justified
“e0” Lead Finish Symbol
(SnPb BGA Balls)
Circle = 1.4 mm Diameter
Center-Justified
Country of Origin
TW
Line 3 Marking:
Rev. 1.1
67
Si5374
DOCUMENT CHANGE LIST

Revision 0.1 to Revision 0.2
Added 1.8 V operation.
Added 40 MHz reference oscillator
 Corrected Figure 10 title.
 Added comment to SFOUT register.


Revision 0.2 to Revision 0.3

Updated and reordered spec tables.
Revision 0.3 to Revision 0.4

Added Silicon Labs logo to device top mark.
Revision 0.4 to Revision 0.45










Added comments indicating that a crystal may not be
used in place of an external oscillator.
Updated specification Tables 3, 4, and 5.
Added maximum jitter specifications to Table 5.
Added Thermal Characteristics table on page 12.
Added Figure 3, “Typical Phase Noise Plot,” on page
14.
Added "5. Si5374 Application Examples and
Suggestions" on page 17.
Updated "7. Register Descriptions" on page 22.
Added a part number for the non-RoHS6 device to
"9. Ordering Guide" on page 63.
Added recommendations on the four reset pins in
"5.4. RSTL_x Pins" on page 17.
Added Lead-Finish top marking.
Revision 0.45 to Revision 1.0

Updated " Features" on page 1.
Revised
output jitter values.
Minor corrections to Tables 2 and 3.
 Added maximum lock and settle time specs to
Table 5.
 Updated "5.5. Reference Oscillator Selection" on
page 17.

Revised
Si530 part number.
Added warning about MEMS reference oscillators to
"5.5. Reference Oscillator Selection" on page 17.
 Added Table 10 in "7.1. ICAL" on page 56.

Revision 1.0 to Revision 1.1
Added reference to AN803 on pages 11, 16, 31 and
60.
 Added additional LOL and Settling Time Specs on
page 11.
 Added new part numbers on page 63.

68
Rev. 1.1
Updates to LOS1_EN and LOS2_EN on pages 53
and 54.
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