MT9042C
Multitrunk System Synchronizer
Advance Information
DS5144
Features
ISSUE 2
September 1999
Ordering Information
•
•
•
•
•
•
•
Meets jitter requirements for: AT&T TR62411
Stratum 3, 4 and Stratum 4 Enhanced for DS1
interfaces; and for ETSI ETS 300 011, TBR 4,
TBR 12 and TBR 13 for E1 interfaces
Provides C1.5, C3, C2, C4, C8 and C16 output
clock signals
Provides 8kHz ST-BUS framing signals
Selectable 1.544MHz, 2.048MHz or 8kHz input
reference signals
Accepts reference inputs from two independent
sources
Provides bit error free reference switching meets phase slope and MTIE requirements
Operates in either Normal, Holdover and
Freerun modes
Applications
•
•
•
Synchronization and timing control for
multitrunk T1 and E1 systems
ST-BUS clock and frame pulse sources
Primary Trunk Rate Converters
MT9042CP
28 Pin PLCC
-40°C to +85 ° C
Description
The MT9042C Multitrunk System Synchronizer
contains a digital phase-locked loop (DPLL), which
provides timing and synchronization signals for
multitrunk T1 and E1 primary rate transmission links.
The MT9042C generates ST-BUS clock and framing
signals that are phase locked to either a 2.048MHz,
1.544MHz, or 8kHz input reference.
The MT9042C is compliant with AT&T TR62411
Stratum 3, 4 and 4 Enhanced, and ETSI ETS 300
011. It will meet the jitter tolerance, jitter transfer,
intrinsic jitter, frequency accuracy, holdover
accuracy, capture range, phase slope and MTIE
requirements for these specifications.
TRST
OSCi
TIE
Corrector
Circuit
Master
Clock
OSCo
PRI
SEC
Reference
Select
TIE
Corrector
Enable
Automatic/Manual
Control State Machine
MS1
MS2
RST
VSS
Virtual
Reference
DPLL
Output
Interface
Circuit
Selected
Reference
Reference
Select
MUX
RSEL
LOS1
LOS2
VDD
State
Select
State
Select
Input
Impairment
Monitor
C1.5o
C3o
C2o
C4o
C8o
C16o
F0o
F8o
F16o
Feedback
Guard Time
Circuit
GTo
GTi
Frequency
Select
MUX
FS1
FS2
Figure 1 - Functional Block Diagram
1
MT9042C
4 3 2 1 28 27 26
5
25
24
6
7
23
22
8
21
9
20
10
19
11
12 13 14 15 16 17 18
RSEL
MS1
MS2
LOS1
LOS2
GTo
GTi
C3o
C2o
C4o
VSS
C8o
C16o
VDD
VDD
OSCo
OSCi
F16o
F0o
F8o
C1.5o
TRST
VSS
RST
FS1
FS2
PRI
SEC
Advance Information
Figure 2 - Pin Connections
Pin Description
2
Pin #
Name
Description (see notes 1 to 5)
1,15
VSS
2
TRST
TIE Circuit Reset (TTL Input). A logic low at this input resets the Time Interval Error (TIE)
correction circuit resulting in a re-alignment of input phase with output phase as shown in
Figure 19. The TRST pin should be held low for a minimum of 300ns.
3
SEC
Secondary Reference (TTL Input). This is one of two (PRI & SEC) input reference
sources (falling edge) used for synchronization. One of three possible frequencies (8kHz,
1.544MHzMHz, or 2.048MHz) may be used. The selection of the input reference is based
upon the MS1, MS2, LOS1, LOS2, RSEL, and GTi control inputs (Automatic or Manual).
4
PRI
Primary Reference (TTL Input). See pin description for SEC.
5,18
VDD
Positive Supply Voltage. +5VDC nominal.
6
OSCo
Oscillator Master Clock (CMOS Output). For crystal operation, a 20MHz crystal is
connected from this pin to OSCi, see Figure 10. For clock oscillator operation, this pin is left
unconnected, see Figure 9.
7
OSCi
Oscillator Master Clock (CMOS Input). For crystal operation, a 20MHz crystal is
connected from this pin to OSCo, see Figure 10. For clock oscillator operation, this pin is
connected to a clock source, see Figure 9.
8
F16o
Frame Pulse ST-BUS 16.384Mb/s (CMOS Output). This is an 8kHz 61ns active low
framing pulse, which marks the beginning of an ST-BUS frame. This is typically used for
ST-BUS operation at 16.384Mb/s. See Figure 20.
9
F0o
Frame Pulse ST-BUS 2.048Mb/s (CMOS Output). This is an 8kHz 244ns active low
framing pulse, which marks the beginning of an ST-BUS frame. This is typically used for
ST-BUS operation at 2.048Mb/s and 4.096Mb/s. See Figure 20.
10
F8o
Frame Pulse ST-BUS 8.192Mb/s (CMOS Output). This is an 8kHz 122ns active high
framing pulse, which marks the beginning of an ST-BUS frame. This is used for ST-BUS
operation at 8.192Mb/s. See Figure 20.
11
C1.5o
Clock 1.544MHz (CMOS Output). This output is used in T1 applications.
12
C3o
Clock 3.088MHz (CMOS Output). This output is used in T1 applications.
13
C2o
Clock 2.048MHz (CMOS Output). This output is used for ST-BUS operation at 2.048Mb/s.
14
C4o
Clock 4.096MHz (CMOS Output). This output is used for ST-BUS operation at 2.048Mb/s
and 4.096Mb/s.
Ground. 0 Volts.
MT9042C
Advance Information
Pin Description
Pin #
Name
Description (see notes 1 to 5)
16
C8o
Clock 8.192MHz (CMOS Output). This output is used for ST-BUS operation at 8.192Mb/s.
17
C16o
Clock 16.384MHz (CMOS Output). This output is used for ST-BUS operation at 16.384Mb/
s.
19
GTi
Guard Time (Schmitt Input). This input is used by the MT9042B state machine in both
Manual and Automatic modes. The signal at this pin affects the state changes between
Primary Holdover Mode and Primary Normal Mode, and Primary Holdover Mode and
Secondary Normal Mode. The logic level at this input is gated in by the rising edge of F8o.
See Tables 4 and 5.
20
GTo
Guard Time (CMOS Output). The LOS1 input is gated by the rising edge of F8o, buffered
and output on GTo. This pin is typically used to drive the GTi input through an RC circuit.
21
LOS2
Secondary Reference Loss (TTL Input). This input is normally connected to the loss of
signal (LOS) output signal of a Line Interface Unit (LIU). When high, the SEC reference
signal is lost or invalid. LOS2, along with the LOS1 and GTi inputs control the MT9042B
state machine when operating in Automatic Control. The logic level at this input is gated in
by the rising edge of F8o.
22
LOS1
Primary Reference Loss (TTL Input). Typically, external equipment applies a logic high to
this input when the PRI reference signal is lost or invalid. The logic level at this input is gated
in by the rising edge of F8o. See LOS2 description.
23
MS2
Mode/Control Select 2 (TTL Input). This input, in conjunction with MS1, determines the
device’s mode (Automatic or Manual) and state (Normal, Holdover or Freerun) of operation.
The logic level at this input is gated in by the rising edge of F8o. See Table 3.
24
MS1
Mode/Control Select 1 (TTL Input). The logic level at this input is gated in by the rising
edge of F8o. See pin description for MS1.
25
RSEL
Reference Source Select (TTL Input). In Manual Control, a logic low selects the PRI
(primary) reference source as the input reference signal and a logic high selects the SEC
(secondary) input. In Automatic Control, this pin must be at logic low. The logic level at this
input is gated in by the rising edge of F8o. See Table 2.
26
FS2
Frequency Select 2 (TTL Input). This input, in conjunction with FS1, selects which of three
possible frequencies (8kHz, 1.544MHz, or 2.048MHz) may be input to the PRI and SEC
inputs. See Table 1.
27
FS1
Frequency Select 1 (TTL Input). See pin description for FS2.
28
RST
Reset (Schmitt Input). A logic low at this input resets the MT9042B. To ensure proper
operation, the device must be reset after changes to the method of control, reference signal
frequency changes and power-up. The RST pin should be held low for a minimum of 300ns.
While the RST pin is low, all frame and clock outputs are at logic high. Following a reset, the
input reference source and output clocks and frame pulses are phase aligned as shown in
Figure 19.
Notes:
1. All inputs are CMOS with either TTL compatible logic levels, CMOS compatible logic levels or Schmitt trigger compatible logic levels
as indicated in the Pin Description.
2. All outputs are CMOS with CMOS compatible logic levels.
3. See DC Electrical Characteristics for static logic threshold values.
4. See AC Electrical Characteristics - Timing Parameter Measurement Voltage Levels for dynamic logic threshold values.
5. Unless otherwise stated, all unused inputs should be connected to logic high or logic low and all unused outputs should be left open
circuit.
3
MT9042C
Advance Information
Functional Description
The MT9042C is a Multitrunk System Synchronizer,
providing timing (clock) and synchronization (frame)
signals to interface circuits for T1 and E1 Primary
Rate Digital Transmission links.
Figure 1 is a functional block diagram which is
described in the following sections.
FS2
FS1
Input Frequency
0
0
Reserved
0
1
8kHz
1
0
1.544MHz
1
1
2.048MHz
Table 1 - Input Frequency Selection
Time Interval Error (TIE) Corrector Circuit
Reference Select MUX Circuit
The TIE corrector circuit, when enabled, prevents a
step change in phase on the input reference signals
(PRI or SEC) from causing a step change in phase at
the input of the DPLL block of Figure 1.
The MT9042C accepts two simultaneous reference
input signals and operates on their falling edges.
Either the primary reference (PRI) signal or the
secondary reference (SEC) signal can be selected
as input to the TIE Corrector Circuit. The selection is
based on the Control, Mode and Reference
Selection of the device. See Tables 1, 4 and 5.
During reference input rearrangement, such as
during a switch from the primary reference (PRI) to
the secondary reference (SEC), a step change in
phase on the output signals will occur. A phase step
at the input of the DPLL will lead to unacceptable
phase changes in the output signal.
Frequency Select MUX Circuit
The MT9042C operates with one of three possible
input reference frequencies (8kHz, 1.544MHz or
2.048MHz). The frequency select inputs (FS1 and
FS2) determine which of the three frequencies may
be used at the reference inputs (PRI and SEC). Both
inputs must have the same frequency applied to
them. A reset (RST) must be performed after every
frequency select input change. Operation with FS1
and FS2 both at logic low is reserved and must not
be used. See Table 1.
As shown in Figure 3, the TIE Corrector Circuit
receives one of the two reference (PRI or SEC)
signals, passes the signal through a programmable
delay line, and uses this delayed signal as an
internal virtual reference, which is input to the DPLL.
Therefore, the virtual reference is a delayed version
of the selected reference.
During a switch, from one reference to the other, the
State Machine first changes the mode of the device
TRST
Resets Delay
Control
Circuit
Control Signal
Delay Value
PRI or SEC
from
Reference
Select Mux
Programmable
Delay Circuit
Virtual
Reference
to DPLL
Compare
Circuit
TIE Corrector
Enable
from
State Machine
Feedback
Signal from
Frequency
Select MUX
Figure 3 - TIE Corrector Circuit
4
MT9042C
Advance Information
Virtual Reference
from
TIE Corrector
Phase
Detector
Feedback Signal
from
Frequency Select MUX
Limiter
Loop Filter
State Select
from
Input Impairment Monitor
Digitally
Controlled
Oscillator
DPLL Reference
to
Output Interface Circuit
Control
Circuit
State Select
from
State Machine
Figure 4 - DPLL Block Diagram
from Normal to Holdover. In Holdover Mode, the
DPLL no longer uses the virtual reference signal, but
generates an accurate clock signal using storage
techniques. The Compare Circuit then measures the
phase delay between the current phase (feedback
signal) and the phase of the new reference signal.
This delay value is passed to the Programmable
Delay Circuit (See Figure 3). The new virtual
reference signal is now at the same phase position
as the previous reference signal would have been if
the reference switch not taken place.
The State
Machine then returns the device to Normal Mode.
The DPLL now uses the new virtual reference signal,
and since no phase step took place at the input of
the DPLL, no phase step occurs at the output of the
DPLL. In other words, reference switching will not
create a phase change at the input of the DPLL, or at
the output of the DPLL.
Since internal delay circuitry maintains the alignment
between the old virtual reference and the new virtual
reference, a phase error may exist between the
selected input reference signal and the output signal
of the DPLL. This phase error is a function of the
difference in phase between the two input reference
signals during reference rearrangements. Each time
a reference switch is made, the delay between input
signal and output signal will change. The value of
this delay is the accumulation of the error measured
during each reference switch.
The programmable delay circuit can be zeroed by
applying a logic low pulse to the TIE Circuit Reset
(TRST) pin. A minimum reset pulse width is 300ns.
This results in a phase alignment between the input
reference signal and the output signal as shown in
Figure 20. The speed of the phase alignment
correction is limited to 5ns per 125us, and
convergence is in the direction of least phase travel.
The state diagrams of Figure 7 and 8 indicate under
which state changes the TIE Corrector Circuit is
activated.
Digital Phase Lock Loop (DPLL)
As shown in Figure 4, the DPLL of the MT9042C
consists of a Phase Detector, Limiter, Loop Filter,
Digitally Controlled Oscillator, and a Control Circuit.
Phase Detector - the Phase Detector compares the
virtual reference signal from the TIE Corrector circuit
with the feedback signal from the Frequency Select
MUX circuit, and provides an error signal
corresponding to the phase difference between the
two. This error signal is passed to the Limiter circuit.
The Frequency Select MUX allows the proper
feedback signal to be externally selected (e.g., 8kHz,
1.544MHz or 2.048MHz).
Limiter - the Limiter receives the error signal from the
Phase Detector and ensures that the DPLL responds
to all input transient conditions with a maximum
output phase slope of 5ns per 125us. This is well
within the maximum phase slope of 7.6ns per 125us
or 81ns per 1.326ms specified by AT&T TR62411.
Loop Filter - the Loop Filter is similar to a first order
low pass filter with a 1.9 Hz cutoff frequency for all
three reference frequency selections (8kHz,
1.544MHz or 2.048MHz). This filter ensures that the
jitter transfer requirements in ETS 300 011 and AT&T
TR62411 are met.
Control Circuit - the Control Circuit uses status and
control information from the State Machine and the
Input Impairment Circuit to set the mode of the
DPLL. The three possible modes are Normal,
Holdover and Freerun.
5
MT9042C
Advance Information
Digitally Controlled Oscillator (DCO) - the DCO
receives the limited and filtered signal from the Loop
FIlter, and based on its value, generates a
corresponding digital output signal.
The
synchronization method of the DCO is dependent on
the state of the MT9042C.
In Normal Mode, the DCO provides an output signal
which is frequency and phase locked to the selected
input reference signal.
The T1 Divider Circuit uses the 12.384MHz signal to
generate two clock outputs. C1.5o and C3o are
generated by dividing the internal C12 clock by four
and eight respectively.
These outputs have a
nominal 50% duty cycle.
The frame pulse outputs (F0o, F8o, F16o) are
generated directly from the C16 clock.
In Holdover Mode, the DCO is free running at a
frequency equal to the last (less 30ms to 60ms)
frequency the DCO was generating while in Normal
Mode.
The T1 and E1 signals are generated from a
common DPLL signal. Consequently, the clock
outputs C1.5o, C3o, C2o, C4o, C8o, C16o, F0o and
F16o are locked to one another for all operating
states, and are also locked to the selected input
reference in Normal Mode. See Figures 20 & 21.
In Freerun Mode, the DCO is free running with an
accuracy equal to the accuracy of the OSCi 20MHz
source.
All frame pulse and clock outputs have limited driving
capability, and should be buffered when driving high
capacitance (e.g., 30pF) loads.
Output Interface Circuit
Input Impairment Monitor
The output of the DCO (DPLL) is used by the Output
Interface Circuit to provide the output signals shown
in Figure 5. The Output Interface Circuit uses two
Tapped Delay Lines followed by a T1 Divider Circuit
and an E1 Divider Circuit to generate the required
output signals.
This circuit monitors the input signal to the DPLL and
automatically
enables
the
Holdover
Mode
(Auto-Holdover) when the frequency of the incoming
signal is outside the auto-holdover capture range (See
AC Electrical Characteristics - Performance). This
includes a complete loss of incoming signal, or a large
frequency shift in the incoming signal. When the
incoming signal returns to normal, the DPLL is
returned to Normal Mode with the output signal locked
to the input signal. The holdover output signal is
based on the incoming signal 30ms minimum to 60ms
prior to entering the Holdover Mode. The amount of
phase drift while in holdover is negligible because the
Holdover Mode is very accurate (e.g., ±0.05ppm). The
the Auto-Holdover circuit does not use TIE correction.
Consequently, the phase delay between the input and
output after switching back to Normal Mode is
preserved (is the same as just prior to the switch to
Auto-Holdover).
T1 Divider
C1.5o
C3o
12MHz
From
DPLL
Tapped
Delay
Line
Tapped
Delay
Line
E1 Divider
16MHz
C2o
C4o
C8o
C16o
F0o
F8o
F16o
Figure 5 - Output Interface Circuit Block
Diagram
Two tapped delay lines are used to generate a
16.384MHz signal and a 12.352MHz signal.
The E1 Divider Circuit uses the 16.384MHz signal to
generate four clock outputs and three frame pulse
outputs.
The C8o, C4o and C2o clocks are
generated by simply dividing the C16o clock by two,
four and eight respectively. These outputs have a
nominal 50% duty cycle.
6
Automatic/Manual Control State Machine
The Automatic/Manual Control State Machine allows
the MT9042C to be controlled automatically (i.e.,
LOS1, LOS2 and GTi signals) or controlled manually
(i.e., MS1, MS2, GTi and RSEL signals). With
manual control a single mode of operation (i.e.,
Normal, Holdover and Freerun) is selected. Under
automatic control the state of the LOS1, LOS2 and
GTi signals determines the sequence of modes that
the MT9042C will follow.
As shown in Figure 1, this state machine controls the
Reference Select MUX, the TIE Corrector Circuit, the
MT9042C
Advance Information
DPLL and the Guard Time Circuit. Control is based
on the logic levels at the control inputs LOS1, LOS2,
RSEL, MS1, MS2 and GTi of the Guard Time Circuit
(See Figure 6).
To
Reference
Select MUX
RSEL
LOS1
LOS2
To TIE
Corrector
Enable
To DPLL
State
Select
Automatic/Manual Control
State Machine
MS1
To
and From
Guard Time
Circuit
MS2
Figure 6 - Automatic/Manual Control State
Machine Block Diagram
All state machine changes occur synchronously on
the rising edge of F8o. See the Controls and Modes
of Operation section for full details on Automatic
Control and Manual Control.
Guard Time Circuit
The GTi pin is used by the Automatic/Manual Control
State Machine in the MT9042C under either Manual
or Automatic control. The logic level at the GTi pin
performs two functions, it enables and disables the
TIE Corrector Circuit (Manual and Automatic), and it
selects which mode change takes place (Automatic
only). See the Applications - Guard Time section.
For both Manual and Automatic control, when
switching from Primary Holdover to Primary Normal,
the TIE Corrector Circuit is enabled when GTi=1, and
disabled when GTi=0.
Under Automatic control and in Primary Normal
Mode, two state changes are possible (not counting
Auto-Holdover). These are state changes to Primary
Holdover or to Secondary Normal. The logic level at
the GTi pin determines which state change occurs.
When GTi=0, the state change is to Primary
Holdover. When GTi=1, the state change is to
Secondary Normal.
Master Clock
The MT9042C can use either a clock or crystal as
the master timing source. For recommended master
timing circuits, see the Applications - Master Clock
section.
Control and Modes of Operation
The MT9042C can operate either in Manual or
Automatic Control. Each control method has three
possible modes of operation, Normal, Holdover and
Freerun.
As shown in Table 3, Mode/Control Select pins MS2
and MS1 select the mode and method of control.
Control
RSEL
Input Reference
MANUAL
0
PRI
1
SEC
0
State Machine Control
AUTO
1
Reserved
Table 2 - Input Reference Selection
MS2
MS1
Control
Mode
0
0
MANUAL
NORMAL
0
1
MANUAL
HOLDOVER
1
0
MANUAL
FREERUN
1
1
AUTO
State Machine Control
Table 3 - Operating Modes and States
Manual Control
Manual Control should be used when either very
simple MT9042C control is required, or when
complex control is required which is not
accommodated by Automatic Control. For example,
very simple control could include operation in a
system which only requires Normal Mode with
reference switching using only a single input stimulus
(RSEL).
Very simple control would require no
external circuitry. Complex control could include a
system which requires state changes between
Normal, Holdover and Freerun Modes based on
numerous input stimuli. Complex control would
require external circuitry, typically a microcontroller.
Under Manual Control, one of the three modes is
selected by mode/control select pins MS2 and MS1.
The active reference input (PRI or SEC) is selected
by the RSEL pin as shown in Table 2. Refer to Table
4 and Figure 7 for details of the state change
sequences.
7
MT9042C
Automatic Control
Automatic Control should be used when simple
MT9042C control is required, which is more complex
than the very simple control provide by Manual
Control with no external circuitry, but not as complex
as Manual Control with a microcontroller.
For
example, simple control could include operation in a
system which can be accommodated by the
Automatic Control State Diagram shown in Figure 8.
Automatic Control is also selected by mode/control
pins MS2 and MS1. However, the mode and active
reference source is selected automatically by the
internal Automatic State Machine (See Figure 6).
The mode and reference changes are based on the
logic levels on the LOS1, LOS2 and GTi control pins.
Refer to Table 5 and Figure 8 for details of the state
change sequences.
Normal Mode
Normal Mode is typically used when a slave clock
source, synchronized to the network is required.
In Normal Mode, the MT9042C provides timing
(C1.5o, C2o, C3o, C4o, C8o and C16o) and frame
synchronization (F0o, F8o, F16o) signals, which are
synchronized to one of two reference inputs (PRI or
SEC). The input reference signal may have a
nominal frequency of 8kHz, 1.544MHz or 2.048MHz.
From a reset condition, the MT9042C will take up to
25 seconds for the output signal to be phase locked
to the selected reference.
The selection of input references is control
dependent as shown in state tables 4 and 5. The
reference frequencies are selected by the frequency
control pins FS2 and FS1 as shown in Table 1.
Holdover Mode
Holdover Mode is typically used for short durations
(e.g., 2 seconds) while network synchronization is
temporarily disrupted.
In Holdover Mode, the MT9042C provides timing and
synchronization signals, which are not locked to an
external reference signal, but are based on storage
techniques. The storage value is determined while
the device is in Normal Mode and locked to an
external reference signal.
8
Advance Information
When in Normal Mode, and locked to the input
reference signal, a numerical value corresponding to
the MT9042C output frequency is stored alternately
in two memory locations every 30ms. When the
device is switched into Holdover Mode, the value in
memory from between 30ms and 60ms is used to set
the output frequency of the device.
The frequency accuracy of Holdover Mode is
±0.05ppm, which translates to a worst case 35 frame
(125us) slips in 24 hours. This exceeds the AT&T
TR62411 Stratum 3 requirement of ±0.37ppm (255
frame slips per 24 hours).
Two factors affect the accuracy of Holdover Mode.
One is drift on the Master Clock while in Holdover
Mode, drift on the Master Clock directly affects the
Holdover Mode accuracy. Note that the absolute
Master Clock (OSCi) accuracy does not affect
Holdover accuracy, only the change in OSCi
accuracy while in Holdover. For example, a ±32ppm
master clock may have a temperature coefficient of
±0.1ppm per degree C. So a 10 degree change in
temperature, while the MT9042C is in Holdover
Mode may result in an additional offset (over the
±0.05ppm) in frequency accuracy of ±1ppm. Which
is much greater than the ±0.05ppm of the MT9042C.
The other factor affecting accuracy is large jitter on
the reference input prior (30ms to 60ms) to the
mode switch. For instance, jitter of 7.5UI at 700Hz
may reduce the Holdover Mode accuracy from
0.05ppm to 0.10ppm.
Freerun Mode
Freerun Mode is typically used when a master clock
source is required, or immediately following system
power-up before network synchronization is
achieved.
In Freerun Mode, the MT9042C provides timing
synchronization signals which are based on
master clock frequency (OSCi) only, and are
synchronized to the reference signals (PRI
SEC).
and
the
not
and
The accuracy of the output clock is equal to the
accuracy of the master clock (OSCi). So if a ±32ppm
output clock is required, the master clock must also
be ±32ppm. See Applications - Crystal and Clock
Oscillator sections.
MT9042C
Advance Information
Description
State
Input Controls
Freerun
Normal
(PRI)
Normal
(SEC)
Holdover
(PRI)
Holdover
(SEC)
MS2
MS1
RSEL
GTi
S0
S1
S2
S1H
S2H
0
0
0
0
S1
-
S1 MTIE
S1
S1 MTIE
0
0
0
1
S1
-
S1 MTIE
S1 MTIE
S1 MTIE
0
0
1
X
S2
S2 MTIE
-
S2 MTIE
S2 MTIE
0
1
0
X
/
S1H
/
-
/
0
1
1
X
/
S2H
S2H
/
-
1
0
X
X
-
S0
S0
S0
S0
Legend:
No Change
/
Not Valid
MTIE
State change occurs with TIE Corrector Circuit
Refer to Manual Control State Diagram for state changes to and from Auto-Holdover State
Table 4 - Manual Control State Table
S0
Freerun
(10X)
S1
Normal
Primary
(000)
{A}
(GTi=0)
(GTi=1)
NOTES:
(XXX)
MS2 MS1 RSEL
{A}
Invalid Reference Signal
S1A
Auto-Holdover
Primary
(000)
S2A
Auto-Holdover
Secondary
(001)
S1H
Holdover
Primary
(010)
S2H
Holdover
Secondary
(011)
{A}
S2
Normal
Secondary
(001)
Phase Re-Alignment
Phase Continuity Maintained (without TIE Corrector Circuit)
Phase Continuity Maintained (with TIE Corrector Circuit)
Movement to Normal State from any
state requires a valid input signal
Figure 7 - Manual Control State Diagram
9
MT9042C
Advance Information
Description
State
Input Controls
Freerun
Normal
(PRI)
Normal
(SEC)
Holdover
(PRI)
Holdover
(SEC)
LOS2
LOS1
GTi
RST
S0
S1
S2
S1H
S2H
1
1
X
0 to 1
-
S0
S0
S0
S0
X
0
0
1
S1
-
S1 MTIE
S1
S1 MTIE
X
0
1
1
S1
-
S1 MTIE
S1 MTIE
S1 MTIE
0
1
0
1
S1
S1H
-
-
S2 MTIE
0
1
1
1
S2
S2 MTIE
-
S2 MTIE
S2 MTIE
1
1
X
1
-
S1H
S2H
-
-
Legend:
No Change
MTIE
State change occurs with TIE Corrector Circuit
Refer to Automatic Control State Diagram for state changes to and from Auto-Holdover State
Table 5 - Automatic Control (MS1=MS2=1, RSEL=0) State Table
(11X)
(11X) RST=1
Reset
S0
Freerun
(X0X)
(01X)
(X0X)
(X0X)
(01X)
(01X)
(X0X)
S1
Normal
Primary
{A}
(01X)
S1A
Auto-Holdover
Primary
S2A
Auto-Holdover
Secondary
S2
Normal
Secondary
{A}
(X0X)
(011)
(11X)
(010 or 11X)
(X0X)
(011)
(01X)
(X00)
S1H
Holdover
Primary
(X01)
(010 or 11X)
NOTES:
(XXX)
LOS2 LOS1 GTi
{A}
Invalid Reference Signal
S2H
Holdover
Secondary
(11X)
Phase Re-Alignment
Phase Continuity Maintained (without TIE Corrector Circuit)
Phase Continuity Maintained (with TIE Corrector Circuit)
Movement to Normal State from any
state requires a valid input signal
Figure 8 - Automatic Control State Diagram
10
MT9042C
Advance Information
MT9042C Measures of Performance
The following are some synchronizer performance
indicators and their corresponding definitions.
It should be noted that 1UI at 1.544MHz is 644ns,
which is not equal to 1UI at 2.048MHz, which is
488ns.
Consequently, a transfer value using
different input and output frequencies must be
calculated in common units (e.g., seconds) as shown
in the following example.
Intrinsic Jitter
Intrinsic jitter is the jitter produced by the
synchronizing circuit and is measured at its output.
It is measured by applying a reference signal with no
jitter to the input of the device, and measuring its
output jitter. Intrinsic jitter may also be measured
when the device is in a non-synchronizing mode,
such as free running or holdover, by measuring the
output jitter of the device. Intrinsic jitter is usually
measured with various bandlimiting filters depending
on the applicable standards.
Jitter Tolerance
Jitter tolerance is a measure of the ability of a PLL to
operate properly (i.e., remain in lock and or regain
lock in the presence of large jitter magnitudes at
various jitter frequencies) when jitter is applied to its
reference. The applied jitter magnitude and jitter
frequency depends on the applicable standards.
What is the T1 and E1 output jitter when the T1 input
jitter is 20UI (T1 UI Units) and the T1 to T1 jitter
attenuation is 18dB?
A
–----- 20
OutputT 1 = InputT 1 ×10
18
–------- 20
OutputT 1 = 20 ×10
= 2.5UI ( T 1 )
( 1UIT 1 )
OutputE1 = OutputT 1 × ---------------------( 1UIE1 )
( 644ns )
OutputE1 = OutputT 1 × ------------------- = 3.3UI ( T 1 )
( 488ns )
Jitter Transfer
Using the above method, the jitter attenuation can be
calculated for all combinations of inputs and outputs
based on the three jitter transfer functions provided.
Jitter transfer or jitter attenuation refers to the
magnitude of jitter at the output of a device for a
given amount of jitter at the input of the device. Input
jitter is applied at various amplitudes and
frequencies, and output jitter is measured with
various filters depending on the applicable
standards.
Note that the resulting jitter transfer functions for all
combinations of inputs (8kHz, 1.544MHz, 2.048MHz)
and
outputs
(8kHz,
1.544MHz,
2.048MHz,
4.096MHz, 8.192MHz, 16.384MHz) for a given input
signal (jitter frequency and jitter amplitude) are the
same.
For the MT9042C, two internal elements determine
the jitter attenuation. This includes the internal
1.9Hz low pass loop filter and the phase slope
limiter. The phase slope limiter limits the output
phase slope to 5ns/125us. Therefore, if the input
signal exceeds this rate, such as for very large
amplitude low frequency input jitter, the maximum
output phase slope will be limited (i.e., attenuated) to
5ns/125us.
The MT9042C has eight outputs with three possible
input frequencies for a total of 24 possible jitter
transfer functions. However, the data sheet section
on AC Electrical Characteristics - Jitter Transfer
specifies transfer values for only three cases, 8kHz
to 8kHz, 1.544MHz to 1.544MHz and 2.048MHz to
2.048MHz. Since all outputs are derived from the
same signal, these transfer values apply to all
outputs.
Since intrinsic jitter is always present,
jitter
attenuation will appear to be lower for small input
jitter signals than for large ones. Consequently,
accurate jitter transfer function measurements are
usually made with large input jitter signals (e.g.,
75% of the specified maximum jitter tolerance).
Frequency Accuracy
Frequency accuracy is defined as the absolute
tolerance of an output clock signal when it is not
locked to an external reference, but is operating in a
free running mode. For the MT9042C, the Freerun
accuracy is equal to the Master Clock (OSCi)
accuracy.
11
MT9042C
Advance Information
Holdover Accuracy
Phase Continuity
Holdover accuracy is defined as the absolute
tolerance of an output clock signal, when it is not
locked to an external reference signal, but is
operating using storage techniques.
For the
MT9042C, the storage value is determined while the
device is in Normal Mode and locked to an external
reference signal.
Phase continuity is the phase difference between a
given timing signal and an ideal timing signal at the
end of a particular observation period. Usually, the
given timing signal and the ideal timing signal are of
the same frequency. Phase continuity applies to the
output of the synchronizer after a signal disturbance
due to a reference switch or a mode change. The
observation period is usually the time from the
disturbance, to just after the synchronizer has settled
to a steady state.
The absolute Master Clock (OSCi) accuracy of the
MT9042C does not affect Holdover accuracy, but the
change in OSCi accuracy while in Holdover Mode
does.
Capture Range
Also referred to as pull-in range. This is the input
frequency range over which the synchronizer must
be able to pull into synchronization. The MT9042C
capture range is equal to ±230ppm minus the
accuracy of the master clock (OSCi). For example, a
±32ppm master clock results in a capture range of
±198ppm.
Lock Range
This is the input frequency range over which the
synchronizer
must
be
able
to
maintain
synchronization. The lock range is equal to the
capture range for the MT9042C.
Phase Slope
Phase slope is measured in seconds per second and
is the rate at which a given signal changes phase
with respect to an ideal signal. The given signal is
typically the output signal. The ideal signal is of
constant frequency and is nominally equal to the
value of the final output signal or final input signal.
Time Interval Error (TIE)
TIE is the time delay between a given timing signal
and an ideal timing signal.
Maximum Time Interval Error (MTIE)
MTIE is the maximum peak to peak delay between a
given timing signal and an ideal timing signal within a
particular observation period.
MTIE ( S ) = TIEmax ( t ) – TIEmin ( t )
12
In the case of the MT9042C, the output signal phase
continuity is maintained to within ±5ns at the
instance (over one frame) of all reference switches
and all mode changes. The total phase shift,
depending on the switch or type of mode change,
may accumulate up to ±200ns over many frames.
The rate of change of the ±200ns phase shift is
limited to a maximum phase slope of approximately
5ns/125us.
This meets the AT&T TR62411
maximum phase slope requirement of 7.6ns/125us
(81ns/1.326ms).
Phase Lock Time
This is the time it takes the synchronizer to phase
lock to the input signal. Phase lock occurs when the
input signal and output signal are not changing in
phase with respect to each other (not including jitter).
Lock time is very difficult to determine because it is
affected by many factors which include:
i) initial input to output phase difference
ii) initial input to output frequency difference
iii) synchronizer loop filter
iv) synchronizer limiter
Although a short lock time is desirable, it is not
always possible to achieve due to other synchronizer
requirements. For instance, better jitter transfer
performance is achieved with a lower frequency loop
filter which increases lock time. And better (smaller)
phase slope performance (limiter) results in longer
lock times. The MT9042C loop filter and limiter were
optimized to meet the AT&T TR62411 jitter transfer
and phase slope requirements.
Consequently,
phase lock time, which is not a standards
requirement, may be longer than in other
applications. See AC Electrical Characteristics Performance for maximum phase lock time.
MT9042C
Advance Information
MT9042C and Network Specifications
Applications
The MT9042C fully meets all applicable PLL
requirements (intrinsic jitter, jitter tolerance, jitter
transfer, frequency accuracy, holdover accuracy,
capture range, phase change slope and MTIE during
reference
rearrangement)
for
the
following
specifications.
This section contains MT9042C application specific
details for clock and crystal operation, guard time
usage, reset operation, power supply decoupling,
Manual Control operation and Automatic Control
operation.
Master Clock
1. AT&T TR62411 (DS1) December 1990 for
Stratum 3, Stratum 4 Enhanced and Stratum 4
2. ANSI T1.101 (DS1) February 1994 for
Stratum 3, Stratum 4 Enhanced and Stratum 4
3. ETSI 300 011 (E1) April 1992 for
Single Access and Multi Access
4. TBR 4 November 1995
The MT9042C can use either a clock or crystal as
the master timing source.
In Freerun Mode, the frequency tolerance at the
clock outputs is identical to the frequency tolerance
of the source at the OSCi pin. For applications not
requiring an accurate Freerun Mode, tolerance of the
master timing source may be ±100ppm.
For
applications requiring an accurate Freerun Mode,
such as AT&T TR62411, the tolerance of the master
timing source must Be no greater than ±32ppm.
5. TBR 12 December 1993
6. TBR 13 January 1996
7. ITU-T I.431 March 1993
Another consideration in determining the accuracy of
the master timing source is the desired capture
range. The sum of the accuracy of the master timing
source and the capture range of the MT9042C will
always equal ±230ppm. For example, if the master
timing source is ±100ppm, then the capture range
will be ±130ppm.
Clock Oscillator - when selecting a Clock Oscillator,
numerous parameters must be considered. This
includes absolute frequency, frequency change over
temperature, output rise and fall times, output levels
and duty cycle. See AC Electrical Characteristics.
MT9042C
OSCi
+5V
+5V
20MHz OUT
GND
0.1uF
OSCo
No Connection
Figure 9 - Clock Oscillator Circuit
For applications requiring ±32ppm clock accuracy,
the following clock oscillator module may be used.
13
MT9042C
Advance Information
CTS CXO-65-HG-5-C-20.0MHz
Frequency:
20MHz
Tolerance:
25ppm 0C to 70C
Rise & Fall Time:
8ns (0.5V 4.5V 50pF)
Duty Cycle:
45% to 55%
Load Capacitance:
32pF
Maximum Series Resistance:
35Ω
Approximate Drive Level:
1mW
e.g., CTS R1027-2BB-20.0MHZ
(±20ppm absolute, ±6ppm 0C to 50C, 32pF, 25Ω)
The output clock should be connected directly (not
AC coupled) to the OSCi input of the MT9042C, and
the OSCo output should be left open as shown in
Figure 9.
Guard Time Adjustment
Crystal Oscillator - Alternatively, a Crystal
Oscillator may be used. A complete oscillator circuit
made up of a crystal, resistor and capacitors is
shown in Figure 10.
MT9042C
OSCi
20MHz
1MΩ
56pF
39pF
3-50pF
AT&T TR62411 recommends that excessive switching
of the timing reference should be minimized. And that
switching between references only be performed when
the primary signal is degraded (e.g., error bursts of 2.5
seconds).
Minimizing switching (from PRI to SEC) in the
MT9042C can be realized by first entering Holdover
Mode for a predetermined maximum time (i.e., guard
time). If the degraded signal returns to normal before
the expiry of the guard time (e.g., 2.5 seconds), then
the MT9042C is returned to its Normal Mode (with no
reference switch taking place).
Otherwise, the
reference input may be changed from Primary to
Secondary.
OSCo
MT9042C
100Ω
1uH
GTo
1uH inductor: may improve stability and is optional
R
150kΩ
Figure 10 - Crystal Oscillator Circuit
+
C
10uF
The accuracy of a crystal oscillator depends on the
crystal tolerance as well as the load capacitance
tolerance. Typically, for a 20MHz crystal specified
with a 32pF load capacitance, each 1pF change in
load capacitance contributes approximately 9ppm to
the frequency deviation. Consequently, capacitor
tolerances, and stray capacitances have a major
effect on the accuracy of the oscillator frequency.
Figure 11 - Symmetrical Guard Time Circuit
The trimmer capacitor shown in Figure 10 may be
used to compensate for capacitive effects.
If
accuracy is not a concern, then the trimmer may be
removed, the 39pF capacitor may be increased to
56pF, and a wider tolerance crystal may be
substituted.
A simple way to control the guard time (using
Automatic Control) is with an RC circuit as shown in
Figure 11. Resistor RP is for protection only and
limits the current flowing into the GTi pin during
power down conditions. The guard time can be
calculated as follows.
GTi
RP
1kΩ
V DD
guard time = RC × ln ----------------------------------
V
–
V
DD
SIH
The crystal should be a fundamental mode type - not
an overtone. The fundamental mode crystal permits
a simpler oscillator circuit with no additional filter
components and is less likely to generate spurious
responses. The crystal specification is as follows.
Frequency:
Tolerance:
Oscillation Mode:
Resonance Mode:
14
20MHz
As required
Fundamental
Parallel
guard time ≈ RC × 0.6
example
guard time ≈ 150k × 10u × 0.6 = 0.9s
•
VSIH is the logic high going threshold level for the
GTi Schmitt Trigger input, see DC Electrical
Characteristics
MT9042C
Advance Information
SEC
SIGNAL
STATUS
GOOD
LOS2
PRI
SIGNAL
STATUS
GOOD
GOOD
BAD
TD
GOOD
BAD
TD
LOS1
GTo
VSIH
GTi
MT9042C
STATE
PRI
NORMAL
PRI
HOLDOVER
PRI
NORMAL
PRI
HOLDOVER
SEC
NORMAL
PRI
NORMAL
NOTES:
1. TD represents the time delay from when the reference goes
bad to when the MT9042C is provided with a LOS indication.
Figure 12 - Automatic Control, Unsymmetrical Guard Time Circuit Timing Example
In cases where fast toggling might be expected of
the LOS1 input, then an unsymmetrical Guard Time
Circuit is recommended. This ensures that reference
switching doesn’t occur until the full guard time value
has expired. An unsymmetrical Guard Time Circuit
is shown in Figure 12.
MT9042C
GTo
+
RC
150kΩ
RD
1kΩ
C
10uF
GTi
RP
1kΩ
TIE Correction (using GTi)
When Primary Holdover Mode is entered for short
time periods, TIE correction should not be enabled.
This will prevent unwanted accumulated phase
change between the input and output. This is mainly
applicable to Manual Control, since Automatic
Control together with the Guard Time Circuit
inherently operate in this manner.
For instance, 10 Normal to Holdover to Normal mode
change sequences occur, and in each case Holdover
was entered for 2s. Each mode change sequence
could account for a phase change as large as 350ns.
Thus, the accumulated phase change could be as
large as 3.5us, and, the overall MTIE could be as
large as 3.5us.
Phase hold = 0.05 ppm × 2s = 100ns
Phase state = 50ns + 200ns = 250ns
Figure 13 - Unsymmetrical Guard Time
Circuit
Figure 13 shows a typical timing example of an
unsymmetrical Guard Time Circuit with the
MT9042C in Automatic Control.
Phase 10 = 10 × ( 250ns + 100ns ) = 3.5us
•
0.05ppm is the accuracy of Holdover Mode
•
50ns is the maximum phase continuity of the
MT9042C from Normal Mode to Holdover Mode
•
200ns is the maximum phase continuity of the
MT9042C from Holdover Mode to Normal Mode (with
or without TIE Corrector Circuit)
15
MT9042C
To Line 1
Advance Information
MT9074
TTIP
To
TX Line
XFMR
TRING
RTIP
To
RX Line
XFMR
DSTo
DSTi
F0i
C4i
RRING
MT9042C
E1.5o
LOS
+ 5V
To Line 2
To
TX Line
XFMR
RTIP
To
RX Line
XFMR
DSTo
DSTi
TRING
+ 5V
FS1
FS2
150kΩ
GTo
GTi
1kΩ
RST
OSCi
1kΩ
10kΩ
+ 5V
TRST
1kΩ
F0i
C4i
LOS1
LOS2
MS1
MS2
RSEL
MT9074
TTIP
F0o
C4o
C2o
PRI
SEC
+
10uF
RRING
E1.5o
LOS
10nF
CLOCK
Out
20MHz ±32ppm
MT8985
STo0
STi0
STo1
STi1
F0i
C4i
Figure 14 - Dual T1 Reference Sources with MT9042C in 1.544MHz Automatic Control
When 10 Normal to Holdover to Normal mode
change sequences occur without MTIE enabled, and
in each case holdover was entered for 2s, each
mode change sequence could still account for a
phase change as large as 350ns. However, there
would be no accumulated phase change, since the
input to output phase is re-aligned after every
Holdover to Normal state change. The overall MTIE
would only be 350ns.
Reset Circuit
A simple power up reset circuit with about a 50us
reset low time is shown in Figure 15. Resistor RP is
for protection only and limits current into the RST pin
during power down conditions. The reset low time is
not critical but should be greater than 300ns.
16
MT9042C
+5V
R
10kΩ
RST
RP
1kΩ
C
10nF
Figure 15 - Power-Up Reset Circuit
MT9042C
Advance Information
To Line 1
To
TX Line
XFMR
MT9075
TTIP
TRING
RTIP
To
RX Line
XFMR
DSTo
DSTi
F0i
C4i
RRING
MT9042C
RxFP
To Line 2
LOS1 C1.5o
LOS2
FS1
MS1
FS2
MS2
RSEL
GTi
TRST
DSTo
DSTi
TRING
OSCi
RST
RTIP
To
RX Line
XFMR
SEC
MT9075
TTIP
To
TX Line
XFMR
F0o
C4o
PRI
LOS
F0i
C4i
+ 5V
CLOCK
Out
20MHz ±32ppm
RRING
RxFP
LOS
External Stimulus
CONTROLLER
MT8985
STo0
STi0
STo1
STi1
F0i
C4i
Figure 16 - Dual E1 Reference Sources with MT9042C in 8kHz Manual Control
Power Supply Decoupling
C1
0.1uF
+
18
15
MT9042C
1
5
+
The MT9042C has two VDD (+5V) pins and two VSS
(GND) pins.
Power and decoupling capacitors
should be included as shown in Figure 17.
C2
0.1uF
Figure 17 - Power Supply Decoupling
17
MT9042C
Advance Information
Absolute Maximum Ratings* -
Voltages are with respect to ground (V SS) unless otherwise stated.
Parameter
Symbol
Min
Max
Units
1
Supply voltage
VDD
-0.3
7.0
V
2
Voltage on any pin
VPIN
-0.3
VDD+0.3
V
3
Current on any pin
IPIN
20
mA
4
Storage temperature
TST
125
°C
5
PLCC package power dissipation
PPD
900
mW
-55
* Exceeding these values may cause permanent damage. Functional operation under these conditions is not implied.
Recommended Operating Conditions* - * Voltages are with respect to ground (VSS) unless otherwise stated.
Characteristics
1
Supply voltage
2
Operating temperature
Sym
Min
Max
Units
VDD
4.5
5.5
V
TA
-40
85
C
DC Electrical Characteristics* - * Voltages are with respect to ground (VSS) unless otherwise stated.
Characteristics
1
Supply current with:
2
Sym
Min
Max
Units
OSCi = 0V
IDDS
10
mA
Outputs unloaded
OSCi = Clock
IDD
60
mA
Outputs unloaded
3
TTL high-level input voltage
VIH
4
TTL low-level input voltage
VIL
5
CMOS high-level input voltage
VCIH
6
CMOS low-level input voltage
VCIL
7
Schmitt high-level input voltage
VSIH
8
Schmitt low-level input voltage
VSIL
9
Schmitt hysteresis voltage
VHYS
0.4
10
Input leakage current
IIL
-10
11
High-level output voltage
VOH
0.8VDD
2.0
V
0.8
0.7VDD
0.3VDD
2.3
0.8
+10
12 Low-level output voltage
VOL
0.2VDD
* Supply voltage and operating temperature are as per Recommended Operating Conditions.
18
Conditions/Notes
V
V
OSCi
V
OSCi
V
GTi, RST
V
GTi, RST
V
GTi, RST
uA
VI=VDD or 0V
V
IOH=4mA
V
IOL=4mA
MT9042C
Advance Information
AC Electrical Characteristics - Performance
Characteristics
Min
Max
Units
Conditions/Notes†
±0ppm
-0
+0
ppm
5-8
2
±32ppm
-32
+32
ppm
5-8
3
±100ppm
-100
+100
ppm
5-8
±0ppm
-0.05
+0.05
ppm
1,2,4,6-8,40
5
±32ppm
-0.05
+0.05
ppm
1,2,4,6-8,40
6
±100ppm
-0.05
+0.05
ppm
1,2,4,6-8,40
±0ppm
-230
+230
ppm
1-3,6-8
8
±32ppm
-198
+198
ppm
1-3,6-8
9
±100ppm
-130
+130
ppm
1-3,6-8
30
s
1-3,6-14
reference switch
200
ns
1-3,6-14
12
mode switch to Normal
200
ns
1-2,4-14
13
mode switch to Freerun
200
ns
1-,4,6-14
14
mode switch to Holdover
50
ns
1-3,6-14
1
4
7
Sym
Freerun Mode accuracy with OSCi at:
Holdover Mode accuracy with OSCi at:
Capture range with OSCi at:
10
Phase lock time
11
Output phase continuity with:
15
MTIE (maximum time interval error)
600
ns
1-14,27
16
Output phase slope
45
us/s
1-14,27
17
Reference input for Auto-Holdover with:
8kHz
-18k
+18k
ppm
1-3,6,9-11
18
1.544MHz
-36k
+36k
ppm
1-3,7,9-11
19
2.048MHz
-36k
+36k
ppm
1-3,8-11
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - Timing Parameter Measurement Voltage Levels* - Voltages are
with respect to ground (VSS) unless otherwise stated.
Characteristics
Sym
Schmitt
TTL
CMOS
Units
VT
1.5
1.5
0.5VDD
V
1
Threshold Voltage
2
Rise and Fall Threshold Voltage High
VHM
2.3
2.0
0.7VDD
V
3
Rise and Fall Threshold Voltage Low
VLM
0.8
0.8
0.3VDD
V
* Supply voltage and operating temperature are as per Recommended Operating Conditions.
* Timing for input and output signals is based on the worst case result of the combination of TTL and CMOS thresholds.
* See Figure 18.
Timing Reference Points
V HM
VT
VLM
ALL SIGNALS
tIRF, tORF
tIRF, tORF
Figure 18 - Timing Parameter Measurement Voltage Levels
19
MT9042C
Advance Information
AC Electrical Characteristics - Input/Output Timing
Characteristics
Min
100
1
Reference input pulse width high or low
tRW
2
Reference input rise or fall time
tIRF
3
8kHz reference input to F8o delay
tR8D
4
1.544MHz reference input to F8o delay
5
Max
Units
ns
10
ns
-21
6
ns
tR15D
337
363
ns
2.048MHz reference input to F8o delay
tR2D
222
238
ns
6
F8o to F0o delay
tF0D
110
134
ns
7
F16o setup to C16o falling
tF16S
11
35
ns
8
F16o hold from C16o rising
tF16H
0
20
ns
9
F8o to C1.5o delay
tC15D
-51
-37
ns
10
F8o to C3o delay
tC3D
-51
-37
ns
11
F8o to C2o delay
tC2D
-13
2
ns
12
F8o to C4o delay
tC4D
-13
2
ns
13
F8o to C8o delay
tC8D
-13
2
ns
14
F8o to C16o delay
tC16D
-13
2
ns
15
C1.5o pulse width high or low
tC15W
309
339
ns
16
C3o pulse width high or low
tC3W
149
175
ns
17
C2o pulse width high or low
tC2W
230
258
ns
18
C4o pulse width high or low
tC4W
111
133
ns
19
C8o pulse width high or low
tC8W
52
70
ns
20
C16o pulse width high or low
tC16WL
24
35
ns
21
F0o pulse width low
tF0WL
230
258
ns
22
F8o pulse width high
tF8WH
111
133
ns
23
F16o pulse width low
tF16WL
52
70
ns
24
Output clock and frame pulse rise or fall time
9
ns
25
Input Controls Setup Time
tS
100
ns
26
Input Controls Hold Time
tH
100
ns
† See "Notes" following AC Electrical Characteristics tables.
20
Sym
tORF
MT9042C
Advance Information
tR8D
PRI/SEC
8kHz
tRW
tR15D
PRI/SEC
1.544MHz
VT
tRW
VT
tR2D
PRI/SEC
2.048MHz
tRW
VT
VT
F8o
NOTES:
1. Input to output delay values
are valid after a TRST or RST
with no further state changes
Figure 19 - Input to Output Timing (Normal Mode)
tF8WH
VT
F8o
tF0D
tF0WL
VT
F0o
tF16WL
VT
F16o
tF16S
tC16WL
tF16H
tC16D
VT
C16o
tC8W
tC8W
tC8D
VT
C8o
tC4W
tC4W
tC4D
VT
C4o
tC2D
tC2W
VT
C2o
tC3W
tC3W
tC3D
VT
C3o
tC15W
tC15D
VT
C1.5o
Figure 20 - Output Timing 1
21
MT9042C
Advance Information
VT
F8o
tS
tH
MS1,2
LOS1,2
RSEL, GTi
VT
Figure 21 - Input Controls Setup and Hold Timing
AC Electrical Characteristics - Intrinsic Jitter Unfiltered
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Intrinsic jitter at F8o (8kHz)
0.0002
UIpp
1-14,21-24,28
2
Intrinsic jitter at F0o (8kHz)
0.0002
UIpp
1-14,21-24,28
3
Intrinsic jitter at F16o (8kHz)
0.0002
UIpp
1-14,21-24,28
4
Intrinsic jitter at C1.5o (1.544MHz)
0.030
UIpp
1-14,21-24,29
5
Intrinsic jitter at C2o (2.048MHz)
0.040
UIpp
1-14,21-24,30
6
Intrinsic jitter at C3o (3.088MHz)
0.060
UIpp
1-14,21-24,31
7
Intrinsic jitter at C4o (4.096MHz)
0.080
UIpp
1-14,21-24,32
8
Intrinsic jitter at C8o (8.192MHz)
0.160
UIpp
1-14,21-24,33
9
Intrinsic jitter at C16o (16.384MHz)
0.320
UIpp
1-14,21-24,34
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - C1.5o (1.544MHz) Intrinsic Jitter Filtered
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Intrinsic jitter (4Hz to 100kHz filter)
0.015
UIpp
1-14,21-24,29
2
Intrinsic jitter (10Hz to 40kHz filter)
0.010
UIpp
1-14,21-24,29
3
Intrinsic jitter (8kHz to 40kHz filter)
0.010
UIpp
1-14,21-24,29
4
Intrinsic jitter (10Hz to 8kHz filter)
0.005
UIpp
1-14,21-24,29
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - C2o (2.048MHz) Intrinsic Jitter Filtered
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Intrinsic jitter (4Hz to 100kHz filter)
0.015
UIpp
1-14,21-24,30
2
Intrinsic jitter (10Hz to 40kHz filter)
0.010
UIpp
1-14,21-24,30
3
Intrinsic jitter (8kHz to 40kHz filter)
0.010
UIpp
1-14,21-24,30
4
Intrinsic jitter (10Hz to 8kHz filter)
0.005
UIpp
1-14,21-24,30
† See "Notes" following AC Electrical Characteristics tables
22
MT9042C
Advance Information
AC Electrical Characteristics - 8kHz Input to 8kHz Output Jitter Transfer
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Jitter attenuation for [email protected] input
0
6
dB
1-3,6,9-14,21-22,24,28,35
2
Jitter attenuation for [email protected] input
6
16
dB
1-3,6,9-14,21-22,24,28,35
3
Jitter attenuation for [email protected] input
12
22
dB
1-3,6,9-14,21-22,24,28,35
4
Jitter attenuation for [email protected] input
28
38
dB
1-3,6,9-14,21-22,24,28,35
5
Jitter attenuation for [email protected] input
42
dB
1-3,6,9-14,21-22,24,28,35
6
Jitter attenuation for [email protected] input
45
dB
1-3,6,9-14,21-22,24,28,35
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - 1.544MHz Input to 1.544MHz Output Jitter Transfer
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Jitter attenuation for 1Hz@20UIpp input
0
6
dB
1-3,7,9-14,21-22,24,29,35
2
Jitter attenuation for 1Hz@104UIpp input
6
16
dB
1-3,7,9-14,21-22,24,29,35
3
Jitter attenuation for 10Hz@20UIpp input
12
22
dB
1-3,7,9-14,21-22,24,29,35
4
Jitter attenuation for 60Hz@20UIpp input
28
38
dB
1-3,7,9-14,21-22,24,29,35
5
Jitter attenuation for 300Hz@20UIpp input
42
dB
1-3,7,9-14,21-22,24,29,35
6
Jitter attenuation for [email protected] input
45
dB
1-3,7,9-14,21-22,24,29,35
7
Jitter attenuation for [email protected] input
45
dB
1-3,7,9-14,21-22,24,29,35
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - 2.048MHz Input to 2.048 MHz Output Jitter Transfer
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Jitter at output for [email protected] input
2.9
UIpp
1-3,8,9-14,21-22,24,30,35
2
with 40Hz to 100kHz filter
0.09
UIpp
1-3,8,9-14,21-22,24,30,36
3
Jitter at output for [email protected] input
1.3
UIpp
1-3,8,9-14,21-22,24,30,35
4
with 40Hz to 100kHz filter
0.10
UIpp
1-3,8,9-14,21-22,24,30,36
5
Jitter at output for [email protected] input
0.80
UIpp
1-3,8,9-14,21-22,24,30,35
6
with 40Hz to 100kHz filter
0.10
UIpp
1-3,8,9-14,21-22,24,30,36
7
Jitter at output for [email protected] input
0.40
UIpp
1-3,8,9-14,21-22,24,30,35
8
with 40Hz to 100kHz filter
0.10
UIpp
1-3,8,9-14,21-22,24,30,36
9
Jitter at output for [email protected] input
0.06
UIpp
1-3,8,9-14,21-22,24,30,35
10
with 40Hz to 100kHz filter
0.05
UIpp
1-3,8,9-14,21-22,24,30,36
11
Jitter at output for [email protected] input
0.04
UIpp
1-3,8,9-14,21-22,24,30,35
12
with 40Hz to 100kHz filter
0.03
UIpp
1-3,8,9-14,21-22,24,30,36
13
Jitter at output for [email protected] input
0.04
UIpp
1-3,8,9-14,21-22,24,30,35
14
with 40Hz to 100kHz filter
0.02
UIpp
1-3,8,9-14,21-22,24,30,36
† See "Notes" following AC Electrical Characteristics tables.
23
MT9042C
Advance Information
AC Electrical Characteristics - 8kHz Input Jitter Tolerance
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Jitter tolerance for 1Hz input
0.80
UIpp
1-3,6,9-14,21-22,24-26,28
2
Jitter tolerance for 5Hz input
0.70
UIpp
1-3,6,9-14,21-22,24-26,28
3
Jitter tolerance for 20Hz input
0.60
UIpp
1-3,6,9-14,21-22,24-26,28
4
Jitter tolerance for 300Hz input
0.20
UIpp
1-3,6,9-14,21-22,24-26,28
5
Jitter tolerance for 400Hz input
0.15
UIpp
1-3,6,9-14,21-22,24-26,28
6
Jitter tolerance for 700Hz input
0.08
UIpp
1-3,6,9-14,21-22,24-26,28
7
Jitter tolerance for 2400Hz input
0.02
UIpp
1-3,6,9-14,21-22,24-26,28
8
Jitter tolerance for 3600Hz input
0.01
UIpp
1-3,6,9-14,21-22,24-26,28
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - 1.544MHz Input Jitter Tolerance
Characteristics
Sym
Min
Max
Units
Conditions/Notes†
1
Jitter tolerance for 1Hz input
150
UIpp
1-3,7,9-14,21-22,24-26,29
2
Jitter tolerance for 5Hz input
140
UIpp
1-3,7,9-14,21-22,24-26,29
3
Jitter tolerance for 20Hz input
130
UIpp
1-3,7,9-14,21-22,24-26,29
4
Jitter tolerance for 300Hz input
35
UIpp
1-3,7,9-14,21-22,24-26,29
5
Jitter tolerance for 400Hz input
25
UIpp
1-3,7,9-14,21-22,24-26,29
6
Jitter tolerance for 700Hz input
15
UIpp
1-3,7,9-14,21-22,24-26,29
7
Jitter tolerance for 2400Hz input
4
UIpp
1-3,7,9-14,21-22,24-26,29
8
Jitter tolerance for 10kHz input
1
UIpp
1-3,7,9-14,21-22,24-26,29
9
Jitter tolerance for 100kHz input
0.5
UIpp
1-3,7,9-14,21-22,24-26,29
† See "Notes" following AC Electrical Characteristics tables.
AC Electrical Characteristics - 2.048MHz Input Jitter Tolerance
Characteristics
Sym
Max
Units
Conditions/Notes†
1
Jitter tolerance for 1Hz input
150
UIpp
1-3,8,9-14,21-22,24-26,30
2
Jitter tolerance for 5Hz input
140
UIpp
1-3,8,9-14,21-22,24-26,30
3
Jitter tolerance for 20Hz input
130
UIpp
1-3,8,9-14,21-22,24-26,30
4
Jitter tolerance for 300Hz input
50
UIpp
1-3,8,9-14,21-22,24-26,30
5
Jitter tolerance for 400Hz input
40
UIpp
1-3,8,9-14,21-22,24-26,30
6
Jitter tolerance for 700Hz input
20
UIpp
1-3,8,9-14,21-22,24-26,30
7
Jitter tolerance for 2400Hz input
5
UIpp
1-3,8,9-14,21-22,24-26,30
8
Jitter tolerance for 10kHz input
1
UIpp
1-3,8,9-14,21-22,24-26,30
9
Jitter tolerance for 100kHz input
1
UIpp
1-3,8,9-14,21-22,24-26,30
† See "Notes" following AC Electrical Characteristics tables.
24
Min
MT9042C
Advance Information
AC Electrical Characteristics - OSCi 20MHz Master Clock Input
Characteristics
1
2
Frequency accuracy
(20 MHz nominal)
3
Sym
Min
Max
Units
-0
+0
ppm
15,18
-32
+32
ppm
16,19
-100
+100
ppm
17,20
40
60
%
4
Duty cycle
5
Rise time
10
ns
6
Fall time
10
ns
Conditions/Notes†
† See "Notes" following AC Electrical Characteristics tables.
† Notes:
Voltages are with respect to ground (VSS) unless otherwise stated.
Supply voltage and operating temperature are as per Recommended Operating Conditions.
Timing parameters are as per AC Electrical Characteristics - Timing Parameter Measurement Voltage Levels
1. PRI reference input selected.
2. SEC reference input selected.
3. Normal Mode selected.
4. Holdover Mode selected.
5. Freerun Mode selected.
6. 8kHz Frequency Mode selected.
7. 1.544MHz Frequency Mode selected.
8. 2.048MHz Frequency Mode selected.
9. Master clock input OSCi at 20MHz ±0ppm.
10. Master clock input OSCi at 20MHz ±32ppm.
11. Master clock input OSCi at 20MHz ±100ppm.
12. Selected reference input at ±0ppm.
13. Selected reference input at ±32ppm.
14. Selected reference input at ±100ppm.
15. For Freerun Mode of ±0ppm.
16. For Freerun Mode of ±32ppm.
17. For Freerun Mode of ±100ppm.
18. For capture range of ±230ppm.
19. For capture range of ±198ppm.
20. For capture range of ±130ppm.
21. 25pF capacitive load.
22. OSCi Master Clock jitter is less than 2nspp, or 0.04UIpp where1UIpp=1/20MHz.
23. Jitter on reference input is less than 7nspp.
24. Applied jitter is sinusoidal.
25. Minimum applied input jitter magnitude to regain synchronization.
26. Loss of synchronization is obtained at slightly higher input jitter amplitudes.
27. Within 10ms of the state, reference or input change.
28. 1UIpp = 125us for 8kHz signals.
29. 1UIpp = 648ns for 1.544MHz signals.
30. 1UIpp = 488ns for 2.048MHz signals.
31. 1UIpp = 323ns for 3.088MHz signals.
32. 1UIpp = 244ns for 4.096MHz signals.
33. 1UIpp = 122ns for 8.192MHz signals.
34. 1UIpp = 61ns for 16.384MHz signals.
35. No filter.
36. 40Hz to 100kHz bandpass filter.
37. With respect to reference input signal frequency.
38. After a RST or TRST.
39. Master clock duty cycle 40% to 60%.
40. Prior to Holdover Mode, device was in Normal Mode and phase locked.
25
MT9042C
Advance Information
F
A
G
D1
D2
D
H
E
E1
e: (lead coplanarity)
A1
Notes:
1) Not to scale
2) Dimensions in inches
3) (Dimensions in millimeters)
4) For D & E add for allowable Mold Protrusion 0.010"
I
E2
20-Pin
28-Pin
44-Pin
68-Pin
84-Pin
Dim
Min
Max
Min
Max
Min
Max
Min
Max
Min
Max
A
0.165
(4.20)
0.180
(4.57)
0.165
(4.20)
0.180
(4.57)
0.165
(4.20)
0.180
(4.57)
0.165
(4.20)
0.200
(5.08)
0.165
(4.20)
0.200
(5.08)
A1
0.090
(2.29)
0.120
(3.04)
0.090
(2.29)
0.120
(3.04)
0.090
(2.29)
0.120
(3.04)
0.090
(2.29)
0.130
(3.30)
0.090
(2.29)
0.130
(3.30)
D/E
0.385
(9.78)
0.395
(10.03)
0.485
(12.32)
0.495
(12.57)
0.685
(17.40)
0.695
(17.65)
0.985
(25.02)
0.995
(25.27)
1.185
(30.10)
1.195
(30.35)
D1/E1
0.350
(8.890)
0.356
0.450
0.456
0.650
0.656
0.950
0.958
1.150
1.158
(9.042) (11.430) (11.582) (16.510) (16.662) (24.130) (24.333) (29.210) (29.413)
D2/E2
0.290
(7.37)
0.330
(8.38)
0.390
(9.91)
0.430
(10.92)
0.590
(14.99)
0.630
(16.00)
0.890
(22.61)
0.930
(23.62)
1.090
(27.69)
1.130
(28.70)
e
0
0.004
0
0.004
0
0.004
0
0.004
0
0.004
F
0.026
(0.661)
0.032
(0.812)
0.026
(0.661)
0.032
(0.812)
0.026
(0.661)
0.032
(0.812)
0.026
(0.661)
0.032
(0.812)
0.026
(0.661)
0.032
(0.812)
G
0.013
(0.331)
0.021
(0.533)
0.013
(0.331)
0.021
(0.533)
0.013
(0.331)
0.021
(0.533)
0.013
(0.331)
0.021
(0.533)
0.013
(0.331)
0.021
(0.533)
H
I
0.050 BSC
(1.27 BSC)
0.020
(0.51)
0.050 BSC
(1.27 BSC)
0.020
(0.51)
0.050 BSC
(1.27 BSC)
0.020
(0.51)
Plastic J-Lead Chip Carrier - P-Suffix
26
0.050 BSC
(1.27 BSC)
0.020
(0.51)
0.050 BSC
(1.27 BSC)
0.020
(0.51)
Advance Information
MT9042C
Notes:
27
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