STS-12/STM-4 or STS-3/STM-1 SONET/SDH Transceiver
Data Sheet


The XRT91L31 is a fully integrated SONET/SDH transceiver for SONET/SDH 622.08 Mbps STS-12/STM-4 or 155.52 Mbps STS-3/STM-1 applications. The transceiver includes an on-chip Clock Multiplier Unit (CMU), which uses a high frequency Phase-Locked Loop (PLL) to generate the high-speed transmit serial clock from a slower external clock reference. It also provides Clock and Data Recovery (CDR) function by synchronizing its on-chip Voltage Controlled Oscillator (VCO) to the incoming serial data stream. The internal CDR unit can be disabled and bypassed in lieu of an externally recovered received clock from the optical module. Either the internally recovered clock or the externally recovered clock can be used for loop timing applications. The chip provides serial-to-parallel and parallel-to-serial converters using an 8-bit wide LVTTL system interface in both receive and transmit directions. The transmit section includes an option to accept a parallel clock signal from the framer/mapper to synchronize the transmit section timing. The device can internally monitor Loss of Signal (LOS) condition and automatically mute received data upon LOS. An on-chip SONET/SDH frame byte and boundary detector and frame pulse generator offers the ability recover SONET/SDH framing and to byte align the receive serial data stream into the 8-bit parallel bus.


  • Targeted for SONET STS-12/STS-3 and SDH STM-4/STM-1 Applications
  • Selectable full duplex operation between STS-12/STM-4 standard rate of 622.08 Mbps or STS-3/STM-1 155.52 Mbps
  • Single-chip fully integrated solution containing parallel-to-serial converter, clock multiplier unit (CMU), serial-to-parallel converter, clock data recovery (CDR) functions, and a SONET/SDH frame and byte boundary detection circuit
  • Ability to disable and bypass onchip CDR for external based received reference clock recovery thru Differential LVPECL input pins XRXCLKIP/N
  • 8-bit LVTTL parallel data bus paths running at 77.76 Mbps in STS-12/STM-4 or 19.44 Mbps in STS-3/STM-1 mode of operation
  • Uses Differential LVPECL or Single-Ended LVTTL CMU reference clock frequencies of either 19.44 MHz or 77.76 MHz for both STS-12/STM-1 or STS-3/STM-1 operations
  • Optional use of 77.76 MHz Single-Ended LVTTL input for independent CDR reference clock operation
  • Able to Detect and Recover SONET/SDH frame boundary and byte align received data on the parallel bus
  • Diagnostics features include LOS monitoring and automatic received data mute upon LOS
  • Provides Local, Remote and Split Loop-Back modes as well as Loop Timing mode
  • Optional flexibility to re-configure the transmit parallel bus clock output to a clock input and accept timing signal from the framer/mapper device to permit the framer/mapper device time domain to be synchronized with the transceiver transmit timing
  • Meets Telcordia, ANSI and ITU-T G.783 and G.825 SDH jitter requirements including T1.105.03 - 2002 SONET Jitter Tolerance specification, Bellcore TR-NWT-000253 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 LVPECL, and JESD 8-B LVTTL and LVCMOS standard
  • Operates at 3.3V with 3.3V I/O
  • Less than 660mW in STS-3/STM-1 mode or 800mW in STS-12/STM-4 mode Typical Power Dissipation
  • Package: 10 x 10 x 2.0 mm 64-pin QFP
  • Pb-Free, RoHS Compliant Versions Offered


  • 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

Simulation Models
Package Type Vcc Temp Mode Version File
LQFP 3.3V Industrial 1


Pkg Code Details Quantities Dimensions PDF
MQFP64 10x10
  • JEDEC Reference: MS-029
  • MSL Pb-Free: L3 @ 260°C
  • MSL SnPb Eutectic: n/a
  • ThetaJA: 45ºC/W
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: 96
  • Quantity per Reel: 1000
  • Quantity per Tube: n/a
  • Quantity per Tray: 96
  • Reel Size (Dia. x Width x Pitch): 330 x 24 x 24
  • Tape & Reel Unit Orientation: Quadrant 2
  • Dimensions: mm
  • Length: 10.00
  • Width: 10.00
  • Thickness: 2.50
  • Lead Pitch: 0.50

Parts & Purchasing

Part Number Pkg Code Min Temp Max Temp Status Buy Now Order Samples
XRT91L31IQ MQFP64 10x10 OBS Suggested:
XRT91L31IQ-F MQFP64 10x10 -40 85 Active Order
XRT91L31IQTR-F MQFP64 10x10 -40 85 OBS Suggested:
Show obsolete parts
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.

Quality & Environmental Data

Part Number RoHS | Exempt RoHS Halogen Free REACH MSL Rating / Peak Reflow Package
XRT91L31IQ-F N Y Y Y L3 / 260ᵒC MQFP64 10x10

Click on the links above to download the Certificate of Non-Use of Hazardous Substances.

Additional Quality Documentation may be available, please Contact Support.
Distribution Date Description File
11/08/2019 MaxLinear has qualified Greatek, Taiwan, as an alternate assembly site for the XRT91L31IQ-F. MaxLinear will also be modifying the marking of the XRT91L31IQ-F assembled at Greatek. The backside marking will be eliminated, while adding the lot number to the topside marking. There is no change to form, fit, function or datasheet.
07/11/2017 Product Discontinuation Notification
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.
03/19/2013 Product Discontinuation Notification Discontinued.


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Frequently Asked Questions

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Type the part into the search, and click on one of the part numbers from the drop down menu. Then you can look for the Product Discontinuation Notice, which generally is at the top of the list, for example:


If you see this, it tells you that this particular orderable part has been discontinued and when the last order date is, or was. If you click on the file, then you can view the notice we sent about this if you purchased the part in the recent past. It may also advise of a replacement part. When an orderable part first becomes discontinued, Product Discontinuation Notices are sent are sent to those who have purchased the parts in the recent past, if purchased directly, with a dated opportunity to place a last order.

The -F suffix indicates ROHS / Green compliance:

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