XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
JUNE 2010
REV. 1.0.1
FEATURES
Performs clock and data recovery for selectable
Enhanced Jitter performance
Meets both Jitter tolerance and generation
requirements
data of 622.08 Mbps (STS-12/STM-4) or 155.52
Mbps (STS-3/STM-1) NRZ data
Meets Telcordia, ANSI and ITU-T G.783 and G.825
SDH jitter requirements including T1.105.03 - 2002
SONET Jitter Tolerance specification, and GR-253
CORE, GR-253 ILR SONET Jitter specifications.
LOCK is a status output that monitors data run
length and frequency drift away from the reference
clock
Data is resampled at the output
Active High Signal Detect (SIGD) LVPECL input
Low jitter, high-speed outputs support LVPECL and
low-power LVDS termination
19.44 MHz reference frequency LVTTL input
Low power: 215 mW typical
3.3V power supply
20-pin TSSOP package
Requires one external capacitor
PLL bypass operation facilitates board debug
process
ESD greater than 2kV on all pins
APPLICATIONS
SONET/SDH-based Transmission Systems
DSLAMS and Add/Drop Multiplexers
Cross Connect Equipment
ATM and Multi-Service Switches, Routers and
Switch/Routers
DWDM Termination Equipment
GENERAL DESCRIPTION
The XRT91L33A is a fully integrated multirate Clock
and Data Recovery (CDR) device for SONET/SDH
622.08 Mbps STS-12/STM-4 or 155.52 Mbps STS-3/
STM-1 applications. The device provides Clock and
Data Recovery (CDR) function by synchronizing its
on-chip Voltage Controlled Oscillator (VCO) to the
incoming serial scrambled non-return to zero (NRZ)
data stream. Figure 1 shows the block diagram of
the XRT91L33A.
FIGURE 1. BLOCK DIAGRAM OF XRT91L33A
STS12_MODE
REFCK
19.44 MHz
CAP+
1u F
CAP-
PLL
RX LOOP
FILTER
TEST
LVDS/LVPECL
Differential
Receiver
Output Drivers
RECVDDATAOUT
RXDIP
RXDATAIN
RXDIN
External
100R
termination
Internal
biasing
0
CDR
STS-12/3
or
STM-4/1
Clock and Data
Recovery
RXDOP
RXDON
1
RECVDCLKOUT
RXCLKOP
RXCLKON
LOCK
LCKTOREFN
SIGD
MUTE
RXDO
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
CLOCK AND DATA RECOVERY OVERVIEW
The clock and data recovery (CDR) unit accepts high speed NRZ serial data from the Differential receiver and
generates a clock with a frequency equal to that of the incoming data. The CDR block uses a reference clock to
train and monitor its clock recovery PLL. Upon startup, the PLL locks to the local reference clock. Once this is
achieved, the PLL attempts to lock onto the incoming receive serial data stream. Whenever the recovered
clock frequency deviates from the local reference clock frequency by more than approximately ±500 ppm, the
clock recovery PLL will switch and lock back onto the local reference clock and declare a Loss of Lock.
Whenever a Loss of Lock or a Loss of Signal event occurs, the CDR will continue to supply a recovered clock
(based on the local reference) to the framer/mapper device. An LOS condition occurs when either SIGD or
LCKTOREFN is low. In this case, the receive serial data output is forced to a logic zero state for the entire
duration of the LOS condition. This acts as a receive data mute upon LOS function to prevent random noise
from being misinterpreted as valid incoming data. When SIGD becomes active again, the recovered clock is
determined to be within ±500 ppm accuracy with respect to the local reference source and LOS is no longer
declared, the clock recovery PLL will switch and lock back onto the incoming receive serial data stream.
FIGURE 2. 20 PIN TSSOP OF XRT91L33A (TOP VIEW)
1
VDDA
VDDA
20
2
RXDIP
VSSA
19
3
RXDIN
CAP+
18
4
VSSA
CAP-
17
5
LOCK
TEST
16
6
STS12_MODE
SIGD
15
7
REFCK
RXDOP
14
8
LCKTOREFN
RXDON
13
9
VSS
RXCLKOP
12
10
VDD
RXCLKON
11
TABLE 1: ORDERING INFORMATION
PART NUMBER
PACKAGE
OPERATING TEMPERATURE RANGE
XRT91L33AIG-F
20-Pin TSSOP Lead-Free Package
-40°C to +95°C
2
XRT91L33A
REV. 1.0.1
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
FEATURES......................................................................................................................... 1
APPLICATIONS ................................................................................................................. 1
GENERAL DESCRIPTION................................................................................................. 1
FIGURE 1. BLOCK DIAGRAM OF XRT91L33A..................................................................................................................................... 1
CLOCK AND DATA RECOVERY OVERVIEW ....................................................................................................... 2
FIGURE 2. 20 PIN TSSOP OF XRT91L33A (TOP VIEW)................................................................................................................... 2
TABLE 1: ORDERING INFORMATION .................................................................................................................................................... 2
1.0 PIN DESCRIPTIONS .............................................................................................................................. 4
TABLE 2: PIN DESCRIPTION TABLE .................................................................................................................................................... 4
2.0 FUNCTIONAL DESCRIPTION ............................................................................................................... 6
2.1
2.2
2.3
2.4
2.5
REFERENCE CLOCK INPUT ...........................................................................................................................
RECEIVE CLOCK AND DATA RECOVERY ....................................................................................................
EXTERNAL RECEIVE LOOP FILTER CAPACITOR .......................................................................................
STS-12/STM-4 AND STS-3/STM-1 MODE OF OPERATION ...........................................................................
SIGNAL DETECTION .......................................................................................................................................
6
6
6
6
6
FIGURE 3. CONTROL DIAGRAM FOR SIGNAL DETECTION CIRCUIT AND PLL TEST OPERATION ............................................................. 7
2.6 LOCK DETECTION ........................................................................................................................................... 7
2.7 TEST PIN OPERATION .................................................................................................................................... 7
TABLE 3: SIGNAL DETECT AND TEST PIN OPERATION CONTROL........................................................................................................ 8
3.0 ELECTRICAL CHARACTERISTICS ..................................................................................................... 9
3.1 ABSOLUTE MAXIMUM RATINGS ................................................................................................................... 9
TABLE 4: ABSOLUTE MAXIMUM RATINGS............................................................................................................................................ 9
3.2 OPERATING CONDITIONS .............................................................................................................................. 9
TABLE 5: RECOMMENDED OPERATING CONDITIONS ........................................................................................................................... 9
3.3 LVPECL SINGLE ENDED INPUT AND OUTPUT DC CHARACTERISTICS .................................................. 9
TABLE 6: LVPECL SINGLE ENDED INPUTS AND OUTPUTS .................................................................................................................. 9
3.4 LVPECL DIFFERENTIAL INPUT AND OUTPUT DC CHARACTERISTICS ................................................. 10
TABLE 7: LVPECL DIFFERENTIAL INPUTS AND OUTPUTS ................................................................................................................. 10
FIGURE 4. DIFFERENTIAL VOLTAGE SWING DEFINITIONS (INPUT OR OUTPUT) FOR CLOCK AND DATA .................................................... 10
TABLE 8: LVDS OUTPUTS............................................................................................................................................................... 10
TABLE 9: LVTTL INPUTS ................................................................................................................................................................. 11
3.5 AC CHARACTERISTICS ................................................................................................................................ 11
TABLE 10: PERFORMANCE SPECIFICATIONS ..................................................................................................................................... 11
4.0 JITTER PERFORMANCE .................................................................................................................... 12
4.1 SONET JITTER REQUIREMENTS ................................................................................................................. 12
4.1.1 RX JITTER TOLERANCE: .......................................................................................................................................... 12
FIGURE 5. GR-253/G.783 JITTER TOLERANCE MASK ...................................................................................................................... 12
FIGURE 6. XRT91L33A JITTER TOLERANCE AT 155 MBPS OC3/STM-1 LOW BANDWIDTH ............................................................. 13
FIGURE 7. XRT91L33A JITTER TOLERANCE AT 155 MBPS OC3/STM-1 HIGH BANDWIDTH ............................................................ 13
FIGURE 8. XRT91L33A JITTER TOLERANCE AT 622 MBPS OC12/STM-4 LOW BANDWIDTH ........................................................... 14
FIGURE 9. XRT91L33A JITTER TOLERANCE AT 622 MBPS OC12/STM-4 HIGH BANDWIDTH .......................................................... 14
4.1.2 JITTER GENERATION................................................................................................................................................ 14
4.1.3 JITTER TRANSFER .................................................................................................................................................... 15
FIGURE 10. XRT91L33A JITTER TRANSFER AT 155 MBPS OC3/STM-1 LOW BANDWIDTH ............................................................. 15
FIGURE 11. XRT91L33A JITTER TRANSFER AT 622 MBPS OC12/STM-4 LOW BANDWIDTH ........................................................... 15
5.0 HIGH-SPEED OUTPUTS ..................................................................................................................... 16
FIGURE 12. HIGH SPEED OUTPUTS, LVDS TERMINATION................................................................................................................. 16
FIGURE 13. HIGH-SPEED OUTPUTS, LVPECL TERMINATION OPTIONS .............................................................................................. 16
6.0 RESAMPLED DATA AND CLOCK OUTPUTS ................................................................................... 17
FIGURE 14. OUTPUT DATA AND CLOCK AFTER RESAMPLING............................................................................................................. 17
TABLE 11: OUTPUT TIMING ............................................................................................................................................................. 17
7.0 PACKAGE DIMENSIONS .................................................................................................................... 18
TABLE 12: REVISION HISTORY ......................................................................................................................................................... 18
3
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
1.0 PIN DESCRIPTIONS
TABLE 2: PIN DESCRIPTION TABLE
NAME
LEVEL
TYPE
PIN
DESCRIPTION
VDDA
PWR
PWR
1
3.3V Power supply
RXDIP
LVDS/PECL
I
2
Positive side of receive data input. The high-speed output clock
(RXCLKOP/N) is recovered from this high-speed differential
input data.
RXDIN
LVDS/PECL
I
3
Negative side of receive data input. The high-speed output
clock (RXCLKOP/N) is recovered from this high-speed differential input data.
VSSA
PWR
PWR
4
Ground pin
LOCK
LVPECL
O
5
Active HIGH to indicate that the PLL is locked to serial data
input and valid clock and data are present at the serial outputs
(RXDOP/N and RXCLKOP/N). The LOCK will go inactive under
the following conditions:
If SIGD is set LOW
If LCKTOREFN is set LOW
If the VCO has drifted away from the local reference
clock, REFCK, by more than +/- 500 ppm
STS12_MODE
LVTTL
I
6
STS-12 or STS-3 mode selection. Set HIGH to select the STS12 operation. Set LOW for STS-3 operation
REFCK
LVTTL
I
7
Local 19.44 MHz reference clock input for the CDR. REFCK is
used for the PLL phase adjustment during power up. It also
serves as a stable clock source in the absence of serial input
data.
LCKTOREFN
LVTTL
I
8
Lock to REFCK input. When set LOW, this pin causes the output clock, RXCLKOP/N to be held within +/- 500ppm of the
input reference clock REFCL and forces the RXDOP/N to a low
state.
VSS
PWR
PWR
9
Ground pin
VDD
PWR
PWR
10
3.3V power supply
RXCLKON
LVDS/
LVPECL
O
11
High-speed clock output, negative. This clock is recovered from
the receive data input (RXDIP/N) and supports either LVDS or
LVPECL termination
RXCLKOP
LVDS/
LVPECL
O
12
High-speed clock output, positive This clock is recovered from
the receive data input (RXDIP/N) and supports either LVDS or
LVPECL. termination
RXDON
LVDS/
LVPECL
O
13
High-speed output, negative This is the retimed version of the
recovered data stream from RXDIP/N and can be in either LVDS
or LVPECL termination
RXDOP
LVDS/
LVPECL
O
14
High-speed output, positive. This is the retimed version of the
recovered data stream from RXDIP/N and can be in either
LVDS or LVPECL termination
4
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
NAME
LEVEL
TYPE
PIN
DESCRIPTION
SIGD
LVPECL
I
15
Signal detect. SIGD should be connected to the SIGD output on
the optical module. SIGD is active HIGH. When SIGD is set
HIGH, it means there is sufficient optical power. When SIGD is
LOW, this indicates an LOS condition, the RXCLKOP/N output
signal will be held to within +/- 500 ppm of the REFCK input.
Additionally, the RXDOP/N will be held in the LOW state.
TEST
LVTTL
I
16
Three-level input: Set to VSS for normal operation, VDD for
improved Jitter transfer characteristics and 1.4V for bypass
mode (used for production testing).
Note: To improve Jitter transfer, set the TEST pin to VDD.
CAP-
Analog
I
17
Negative side of the external loop filter. The loop filter capacitor
should be connected to these pins. The capacitor value should
be 1.0 F +/- 10%
CAP+
Analog
I
18
Positive side of the external loop filter. The loop filter capacitor
should be connected to these pins. The capacitor value should
be 1.0 F +/- 10%.
VSSA
PWR
PWR
19
Ground pin
VDDA
PWR
PWR
20
3.3V power supply
5
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
2.0 FUNCTIONAL DESCRIPTION
The XRT91L33A CDR is designed to operate with a SONET Framer/ASIC device and provide a high-speed
serial clock and data recovery interface to optical networks. The CDR receives a differential NRZ serial bit
stream running at STS-12/STM-4 or STS-3/STM-1 and generates recovered serial clock and data via
differential LVDS/LVPECL drivers.
2.1
Reference Clock Input
The XRT91L33A accepts a 19.44 MHz LVTTL clock input at REFCK. The REFCK should be generated from a
source that has a frequency accuracy better than ±100ppm in order for the CDR Loss of Lock detector to have
the necessary accuracy required for SONET systems.
2.2
Receive Clock and Data Recovery
The clock and data recovery (CDR) unit accepts the high-speed NRZ serial data from the Differential receiver
and generates a clock that is the same frequency as the incoming data. The clock recovery block utilizes the
reference clock from REFCK to train and monitor its clock recovery PLL. Upon startup, the PLL locks to the
local reference clock. Once this is achieved, the PLL then attempts to lock onto the incoming receive serial
data stream. Whenever the recovered clock frequency deviates from the local reference clock frequency by
more than approximately ±500ppm, the clock recovery PLL will switch to the local reference clock, declare a
Loss of Lock and output a LOW level signal on the LOCK output pin. Whenever a Loss of Lock (LOL) or a Loss
of Signal (LOS) event occurs, the CDR will continue to supply a receive clock (based on the local reference).
2.3
External Receive Loop Filter Capacitor
For STS12/STM4 and STS3/STM1 operation, the XRT91L33A uses a 1.0uF external loop filter capacitor to
achieve the required receiver jitter performance. It must be well isolated to prohibit noise entering the CDR
block and should be placed as close to the pins as possible. The non-polarized capacitor should be of ±10%
tolerance. Use type X7R or X5R capacitors for improved stability over temperature.
2.4
STS-12/STM-4 and STS-3/STM-1 Mode of Operation
The VCO output signal is fed into a programmable frequency divider allowing one to properly set the PLL
operating frequency corresponding to the desired data rate. For 622.08 Mbps signal STS12_MODE is set
HIGH and for 155.52 Mbps, STS12_MODE is set LOW.
2.5
Signal Detection
XRT91L33A has two control pins that are used to indicate an LOS condition (Loss Of Signal). The SIGD pin is
a LVPECL input and the LCKTOREFN pin is a LVTTL input. They are internally connected as shown in Figure
3. If either of these two inputs goes LOW and TEST is LOW or HIGH, XRT91L33A will enter a Loss of Signal
(LOS) state, and will mute the RXDOP/N. During the LOS state, XRT91L33A will also maintain RXCLKOP/N
within ±500ppm of the input reference clock, REFCK. Most optical modules have an SIGD output. This SIGD
output indicates that there is sufficient optical power and is typically active HIGH. If the SIGD output on the
optical module is LVPECL, it should be connected directly to the SIGD input of XRT91L33A, and the
LCKTOREFN input should be tied HIGH. If the SIGD output is LVTTL, it should be connected directly to the
LCKTOREFN input and the SIGD input should be tied HIGH. The SIGD and LCKTOREFN inputs also can be
used for other applications when it is required to hold RXCLKOP/N output within ±500ppm of the input
reference clock and mute the serial data output lines.
6
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
FIGURE 3. CONTROL DIAGRAM FOR SIGNAL DETECTION CIRCUIT AND PLL TEST OPERATION
RXDIP/N
2
PLL Clock
(Internal )
REFCK
2
RXDOP/N
0
2
RXCLKOP/N
1
STS12_ Mode
TEST
BW Select (Internal)
LOS (Internal )
LOCKTOREFN
SIGD
2.6
Lock Detection
XRT91L33A features a PLL lock detection circuit. The lock detect (LOCK) output goes HIGH to indicate that
the PLL is locked to the serial data input and valid data and clock are present at the high-speed differential
output. The LOCK output will go LOW if either the LOCKTOREFN or the SIGD input is forced LOW.
Additionally, LOCK will also go low if the incoming data frequency is more than +/-500ppm away from the
reference clock frequency (REFCK x 32 in OC12 mode, REFCK x 8 in OC3 mode). When LOCK output is
driven LOW, the VCO is forced to lock to REFCK and then released to lock on the incoming data. If the
incoming data frequency remains outside the +/-500ppm window, the training mode is repeated. Debounce
logic stabilizes the LOCK output pin to stay LOW for incoming frequencies well beyond the +/-500ppm window.
2.7
Test Pin Functionality
The TEST pin on the XRT91L33A is a three-level control input - VDD, VSS and 1.4V. This pin determines the
test (bypass) mode operation and controls the bandwidth of the PLL. Pulling this pin low sets the high
bandwidth operation and is used for normal operation. Pulling this pin high sets the low bandwidth operation
that is used for improved SONET jitter transfer performance. Applying 1.4V to the input configures the device
into a bypass mode for use in production test.
2.7.1
Normal Operation
If the Test pin is held low the part functions normally with similar performance to the XRT91L33A.
bandwidth is configured for high bandwidth.
2.7.2
The PLL
Improved Jitter Transfer Operation
If the Test pin is held high the part optimizes the SONET jitter transfer performance. This mode is offered for
applications where the jitter transfer characteristics are more critical. The PLL bandwidth is configured for low
bandwidth.
2.7.3
Bypass Mode Operation
If TEST is set to 1.4V and STS12_MODE pin is set to logic HIGH, XRT91L33A will bypass the PLL and present
an inverted version of the REFCK to the clock output RXCLKOP/N. REFCK’s rising edge is used to capture the
input data and transmit data to RXDOP/N. This bypass test operation can be used to facilitate board level
debugging process.
7
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
.
TABLE 3: SIGNAL DETECT AND TEST PIN OPERATION CONTROL
STS12_MODE
TEST
LCKTOREFN
SIGD
RXDO
RXCLKO
1
1 or 0
1
1
RXDI
PLL clock
1
1 or 0
1
0
Muted
PLL clock
1
1 or 0
0
1
Muted
PLL clock
1
1 or 0
0
0
Muted
PLL clock
1
1.4V
X
X
RXDI
REFCK
0
1 or 0
1
1
RXDI
PLL clock
0
1 or 0
1
0
Muted
PLL clock
0
1 or 0
0
1
Muted
PLL clock
0
1 or 0
0
0
Muted
PLL clock
0
1.4V
X
X
Not allowed
Not allowed
8
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
3.0 ELECTRICAL CHARACTERISTICS
3.1
Absolute Maximum RATINGS
TABLE 4: ABSOLUTE MAXIMUM RATINGS
SYMBOL
VDD
TS
VESD
3.2
PARAMETER
MINIMUM MAXIMUM UNIT
Power supply voltage, referenced to GND
-0.5
4.0
V
DC input voltage (LVPECL, LVTTL)
-0.5
VDD+0.5
V
Output current (LVDS or LVPECL)
-50
+50
mA
Storage Temperature
-65
150
C
-2000
2000
V
Electrostatic discharge voltage, human body model
Operating Conditions
TABLE 5: RECOMMENDED OPERATING CONDITIONS
SYMBOL
VDD
Temp
PARAMETER
Power supply voltage
MIN.
TYP
MAX.
UNITS
3.135
3.3
3.465
V
95
C
-40
Operating Temperature under bias 1
IDD
Power supply current (outputs unterminated)
71
80
mA
PD
Power dissipation (outputs unterminated)
234
277
mW
1. Lower limit of specification is ambient temperature, and upper limit is case temperature.
3.3
LVPECL Single Ended Input and Output DC characteristics
TABLE 6: LVPECL SINGLE ENDED INPUTS AND OUTPUTS
SYMBOL
PARAMETER
MIN.
TYP.
MAX.
UNITS
CONDITIONS
VIH
Input HIGH voltage
VDD-1.125
VDD-0.5
V
Guaranteed input
HIGH voltage
VIL
Input LOW voltage
VDD-2.0
VDD-1.5
V
Guaranteed input
LOW voltage
IIH
Input HIGH current
-0.5
10
A
VIN = VDD - 0.5V
IIL
Input LOW current
-0.5
10
A
VIN=VDD-2.0V
VOL
Output LOW voltage
VDD-2.0
VDD-1.8
V
50 to (VDD-2.0V)
VOH
Output HIGH voltage
VDD-1.25
VDD-0.67
V
50 to (VDD-2.0V)
9
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
3.4
REV. 1.0.1
LVPECL Differential Input and Output DC characteristics
TABLE 7: LVPECL DIFFERENTIAL INPUTS AND OUTPUTS
SYMBOL
PARAMETER
MIN.
TYP.
MAX.
UNITS
CONDITIONS
VIH
Input HIGH voltage
VDD-1.75
VDD-0.4
V
Guaranteed input
HIGH voltage
VIL
Input LOW voltage
VDD-2.0
VDD-0.7
V
Guaranteed input
LOW voltage
IIH
Input HIGH current
-0.5
10
A
VIN DIFF =0.5V
IIL
Input LOW current
-0.5
10
A
VIN DIFF =0.5V
VIDIFF
Input PECL Differential Voltage, peakto-peak swing (see Figure 4)
250
VOCM
Output Common-Mode Voltage
0.8
VODIFF
Output LVPECL Differential Voltage,
peak-to-peak swing (see Figure 4)
800
mV
1.35
1.7
V
50 to (VDD-2.0V)
1700
mV
50 to (VDD-2.0V)
FIGURE 4. DIFFERENTIAL VOLTAGE SWING DEFINITIONS (INPUT OR OUTPUT) FOR CLOCK AND DATA
V(+)
V SING LE
V(-)
V DIFF = V(+)-V(-)
2 x V SINGLE
0V
TABLE 8: LVDS OUTPUTS
SYMBOL
PARAMETER
MIN.
TYP.
MAX.
UNITS
CONDITIONS
1.35
1.7
V
100 between
RXDOP/N and
RXCLKP/N
1700
mV
100 between
RXDOP/N and
RXCLKP/N
VOCM
Output common-mode voltage
1.0
VODIFF
Output LVDS Differential Voltage,
peak-to-peak Swing (see Figure 4)
700
10
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
TABLE 9: LVTTL INPUTS
SYMBOL
PARAMETER
MIN.
TYP.
MAX.
UNITS
CONDITIONS
VIH
Input HIGH voltage
2.0
VDD
V
VIL
Input LOW voltage
0
0.8
V
IIH
Input HIGH current
-50
50
A
VIN = 2.75 V, VDD =
Maximum
IIL
Input LOW current
-50
50
A
VIN = 0.5 V, VDD =
Maximum
3.5
AC Characteristics
TABLE 10: PERFORMANCE SPECIFICATIONS
Test Condition: VDD = 3.3V + 5% unless otherwise specified
SYMBOL
f
fTOL
fTREF_CLK
PARAMETER
MIN
VCO center frequency
TYP
MAX
622.08
UNITS
CONDITIONS
MHz
CDR’s reference clock frequency
-250
250
ppm
OC-12/STS-12 capture range
-500
500
ppm
with respect to the fixed
reference frequency
45
55
% UI
20% minimum transition
density
CLKOUTDC
Clock output duty cycle
tLOCK
OC-12/STS-12 acquisition lock time
16
s
Valid REFCK and
device already powered up
tLOCK_R,
tLOCK_F
LOCK output rise and fall time
500
ps
10% to 90%, with 100
and 5 pF capacitive
equivalent load
JGEN_CLCK
RXCLKOP/N jitter generation
0.01
UIrms
JTOL
OC-12/STS-12 jitter tolerance
0.005
0.40
11
0.5
UI
Sinusoidal input jitter of
RXDIP/N from 250 KHz
to 5MHz
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
4.0 JITTER PERFORMANCE
4.1
SONET Jitter Requirements
SONET receive equipment jitter requirements are specified jitter tolerance and jitter transfer. The definitions of
each of these types of jitter are given below.
4.1.1
Rx Jitter Tolerance:
OC-3/STM-1, and OC-12/STM-4 category II SONET interfaces should tolerate, the input jitter applied
according to the mask of Figure 5, with the corresponding specified parameters. Jitter measurements are
done with standard SONET/SDH testers such as Acterna ANT20 as well as Agilent Omniber testers.
FIGURE 5. GR-253/G.783 JITTER TOLERANCE MASK
A3
slope= -20dB/decade
Input
Jitter
Amplitude
(UIpp)
A2
slope= -20dB/decade
A1
f0
f1
f2
f4
f3
Jitter Frequency (Hz)
OC-N
F0 (HZ)
F1 (HZ)
F2 (HZ)
F3 (HZ)
F4 (HZ)
A1 (UIPP)
A2 (UIPP)
A3 (UIPP)
OC1/STS11
STM-X LEVEL
STM0
10
30
300
2K
20K
0.15
1.5
15
OC3/STS33
STM1
10
30
300
6.5K
65K
0.15
1.5
15
OC12/STS12
STM4
12
10
30
300
25K
250K
0.15
1.5
15
12
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
FIGURE 6. XRT91L33A JITTER TOLERANCE AT 155 MBPS OC3/STM-1 (LOW BANDWIDTH)
XRT91L33A OC-3 LOW BANDWIDTH JITTER TOLERANCE
100.00
JITTER TOL.@ 1.3MHz = >0.60UI
VDD = 3.3V, TA = 25C
AMPLITUDE, UI
10.00
1.00
0.10
1
10
100
1000
10000
100000
1000000
10000000
FREQUENCY, Hz
MASK, UI
VDD = 3.30V
FIGURE 7. XRT91L33A JITTER TOLERANCE AT 155 MBPS OC3/STM-1 (HIGH BANDWIDTH)
XRT91L33A OC-3 HIGH BANDWIDTH JITTER TOLERANCE
100.00
JITTER TOL.@ 1.3MHz = >0.60UI
VDD = 3.3V, TA = 25C
AMPLITUDE, UI
10.00
1.00
0.10
1
10
100
1000
10000
100000
FREQUENCY, Hz
MASK, UI
VDD = 3.30V
13
1000000
10000000
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
FIGURE 8. XRT91L33A JITTER TOLERANCE AT 622 MBPS OC12/STM-4 (LOW BANDWIDTH)
XRT91L33A OC-12 LOW BANDWIDTH JITTER TOLERANCE
1000
VDD = 3.3V, TA = 25C
AMPLITUDE, UI
100
10
1
0.1
1
10
100
1000
10000
100000
1000000
10000000
FREQUENCY, Hz
MASK, UI
VDD = 3.30V
FIGURE 9. XRT91L33A JITTER TOLERANCE AT 622 MBPS OC12/STM-4 (HIGH BANDWIDTH)
XRT91L33A OC-12 HIGH BANDWIDTH JITTER TOLERANCE
1000
VDD = 3.0V, TA = 25C
AMPLITUDE, UI
100
10
1
0.1
1
10
100
1000
10000
100000
1000000
10000000
FREQUENCY, Hz
MASK, UI
4.1.2
VDD = 3.30V
Jitter Generation
Maximum jitter generation is less than 0.01 UI rms within the SONET/SDH band, when rms jitter of less than
14 ps (OC-12) or 56 ps (OC-3) is presented to the serial data inputs.
14
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
4.1.3
Jitter Transfer
When in the Low Bandwidth mode (Test pin = VDD) the XRT91L33A does meet the jitter transfer requirement
in the ITU standard.
FIGURE 10. XRT91L33A JITTER TRANSFER AT 155 MBPS OC3/STM-1 (LOW BANDWIDTH)
XRT91L33A OC-3 LOW BANDWIDTH TRANSFER FUNCTION
5.00
VDD = 3.3V, TA = 25qC
0.00
LOW BW -3dB pt.
= 65.54KHz
-3.00
-5.00
MASK, UI
GAIN, dB
-10.00
-15.00
-20.00
-25.00
-30.00
1
10
100
1000
10000
100000
1000000
10000000
FREQUENCY, Hz
FIGURE 11. XRT91L33A JITTER TRANSFER AT 622 MBPS OC12/STM-4 (LOW BANDWIDTH)
XRT91L33A OC-12 LOW BANDWITH TRANSFER FUNCTION
5.00
VDD = 3.3V, TA = 25qC
0.00
LO BW -3dB pt.
-3.00
-5.00
MASK, UI
GAIN, dB
-10.00
-15.00
-20.00
-25.00
-30.00
1
10
100
1000
10000
FREQUENCY, Hz
15
100000
1000000
10000000
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
5.0 HIGH-SPEED OUTPUTS
The high-speed output buffers, RXDOP/N and RXCLKOP/N can be terminated as either LVDS or LVPECL
outputs. In LVDS mode, the transmission lines must be routed with 100 differential impedance and
terminated at the receive end with a line-to-line 100 resistor (See Figure 12).
FIGURE 12. HIGH SPEED OUTPUTS, LVDS TERMINATION
XRT91L33A
100 Ohm
Receiver
For LVPECL connections, the transmission line must be terminated with 50 pull-down resistors near the
receiving end or an equivalent circuit. (See Figure 13)
FIGURE 13. HIGH-SPEED OUTPUTS, LVPECL TERMINATION OPTIONS
50 Ohm
VDD – 2.0V
Receiver
50 Ohm
XRT91L33A
VDD – 2.0V
Creates 2V bias
when VDD = 3.3V
82 Ohm
VDD
XRT91L33A
Receiver
168 Ohm
VDD
124 Ohm
168 Ohm
VSS
Unbiased (No internal
termination)
VSS
XRT91L33A
168 Ohm
168 Ohm
Receiver
(Baised with internal
termination)
16
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
6.0 RESAMPLED DATA AND CLOCK OUTPUTS
It is recommended that the retimed data output be captured with the rising edge of the clock output as shown in
Figure 14. Data valid time is longer for OC-3/STS-3 mode of operation than that of OC-12/STS-12. Data valid
time before the output clock’s rising edge is the available setup time (tSU), while the data valid time after the
clock’s rising edge is the available hold time (tH).
FIGURE 14. OUTPUT DATA AND CLOCK AFTER RESAMPLING
RXDOP/N
RXCLKOP/N
tH
tSU
TABLE 11: OUTPUT TIMING
SYMBOL
tSU
tH
PARAMETER
Available setup time
Available hold time
MINIMUM
MAXIMUM
UNIT
CONDITION
450
ps
STS-12 operation (622.08 MHz)
2.0
ns
STS-3 operation (155.52 MHz)
650
ps
STS-12 operation (622.08 MHz)
3.0
ns
STS-3 operation (155.52 MHz)
17
XRT91L33A
STS-12/STS-3 MULTIRATE CLOCK AND DATA RECOVERY UNIT
REV. 1.0.1
7.0 PACKAGE DIMENSIONS
20 pin Surface mount TSSOP
TABLE 12: REVISION HISTORY
REVISION #
DATE
1.0.0
March 2010
1.0.1
June 2010
DESCRIPTION
Initial release of Final Product Datasheet
Changed the maximum temperature to 95oC, updated the typical IDD and typical
power values in the electrical table.
18