Quad Channel Multirate STS-12/3/1 and STM-4/1/0 SONET/SDH CDR


The XRT91L34 is a fully integrated quad channel 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 or 51.84 Mbps STS-1/STM-0 applications. The device provides Clock and Data Recovery (CDR) function by synchronizing its on-chip Voltage Controlled Oscillator (VCO) to the incoming serial data stream. The device internally monitors Loss of Lock (LOL) conditions and automatically mutes recovered data upon Loss of Signal (LOS) conditions.

Clock and Data Recovery Overview

The clock and data recovery (CDR) unit accepts the high speed NRZ serial data from the LVDS or Differential LVPECL receiver and generates a clock that is the same frequency as the incoming data. The CDR block uses a reference clock to train and monitor its clock recovery PLL. All four channels share a single 77.76MHz or 19.44MHz reference clock. 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. When the SDEXT is de-asserted by the optical module or when internal DLOS is asserted, the receive serial data output will be forced to a logic zero state for the entire duration that a LOS condition is declared. This acts as a receive data mute upon LOS function to prevent random noise from being misinterpreted as valid incoming data. When the SDEXT becomes active and 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.

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  • Quad Channel CDR targeted for SONET STS-12/STS-3/STS-1 and SDH STM-4/STM-1/STM-0 Applications
  • Selectable data rate operation between 622.08 Mbps, 155.52 Mbps, or 51.84 Mbps
  • Single-chip fully integrated solution containing quad-channel clock and data recovery (CDR) functions
  • Optional flexibility to configure for LVDS or Differential LVPECL High Speed I/O Interface
  • Internal 100W termination for the high speed LVDS/Differential LVPECL inputs included
  • Utilizes reference clock frequency of either 19.44 MHz or 77.76 MHz
  • Host mode serial microprocessor interface simplifies monitor and control, including LOS monitoring
  • Diagnostics features include LOS monitoring in Host Mode and automatic recovered data mute upon LOS
  • Loss of Lock Detect output for each channel
  • Permits mixed data rate configuration of the four channels
  • Independent power down control of unused channels for lower power operation
  • 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
  • Complies with ANSI/TIA/EIA-644 and IEEE P1596.3 3.3V LVDS standard, 3.3V Differential LVPECL, and JESD 8-B LVTTL and LVCMOS standard
  • Operates with dual power supply of 1.8V core and 3.3V IO supply
  • 90mW LVDS/ 350mW Differential LVPECL per channel Typical Power Dissipation
  • Package: 14 x 14 x 1.4 mm 128-pin LQFP
  • RoHS Compliant Lead-Free package availability
  • ESD greater than 2kV on all pins


  • SONET/SDH-based Transmission Systems
  • Add/Drop Multiplexers
  • Cross Connect Equipment
  • ATM and Multi-Service Switches, Routers and Switch/Routers
  • SONET/SDH Test Equipment
  • DWDM Termination Equipment

Design Tools


Pkg Code Details Quantities Dimensions PDF
LQFP128 14x14
  • JEDEC Reference: MS-026
  • MSL Pb-Free: L3 @ 260°C
  • MSL SnPb Eutectic: n/a
  • ThetaJA: n/a
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: n/a
  • Quantity per Reel: 1000
  • Quantity per Tube: n/a
  • Quantity per Tray: 90
  • Reel Size (Dia. x Width x Pitch): 330 x 24 x 20
  • Tape & Reel Unit Orientation: Pin 1 at sprocket hole.
  • Dimensions: mm
  • Length: 14.00
  • Width: 14.00
  • Thickness: 1.60
  • Lead Pitch: 1.00

Parts & Purchasing

Part Number Pkg Code RoHS Min Temp Max Temp Status Buy Now Order Samples
XRT91L34IV-F LQFP128 14x14 -40 85 Active
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Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.
Distribution Date Description File
07/26/2016 Product discontinuation notification. Discontinued. PDN 16-0626-01-1033.pdf
12/05/2013 Addition of an alternate qualified assembly site, ASE Chung-Li (Taiwan) for assembly using copper or gold wire bonding. Material change and alternate assembly site. PCN_13-0521-02-1033.pdf