Quad T1/E1/J1 Transceiver

Please check latest availability status for a specific part variant.


The DS21Q55 is a quad software-selectable T1, E1, or J1 MCM device for short-haul and long-haul applications. Each port is composed of a line interface unit (LIU), framer, HDLC controllers, and a TDM backplane interface, and is controlled by an 8-bit parallel port configured for Intel or Motorola bus operations. The DS21Q55 is software compatible with the DS2155 single-chip transceiver. It is pin compatible with the DS21Qx5y family of products.
DS21Q55, DS21Q55N: Block Diagram DS21Q55, DS21Q55N: Block Diagram Enlarge+

Key Features

  • Complete T1/DS1/ISDN-PRI/J1 Transceiver Functionality
  • Complete E1 (CEPT) PCM-30/ISDN-PRI Transceiver Functionality
  • Long-Haul and Short-Haul Line Interface for Clock/Data Recovery and Waveshaping
  • CMI Coder/Decoder for Optical I/F
  • Crystal-Less Jitter Attenuator
  • Fully Independent Transmit and Receive Functionality
  • Dual HDLC Controllers
  • Programmable BERT Generator and Detector
  • Internal Software-Selectable Receive and Transmit-Side Termination Resistors for 75Ω /100Ω /120Ω T1 and E1 Interfaces
  • Dual Two-Frame Elastic-Store Slip Buffers that Connect to Asynchronous Backplanes Up to 16.384MHz
  • 16.384MHz, 8.192MHz, 4.096MHz, or 2.048MHz Clock Output Synthesized to Recovered Network Clock


  • Channel Banks
  • Channel Service Units (CSUs)
  • Data Service Units (DSUs)
  • DSL Add/Drop Multiplexers
  • Muxes
  • Routers/Switches
  • Routers/Switches
  • T1/E1 Test Equipment

Quality and Environmental Data

Request Reliability Report for: DS21Q55N 
Lead-Free Package Tin (Sn) Whisker Reports
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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Related Resources

Belle Isle 2020
05/29/2020 - 05/31/2020, Detroit, MI
2020 Detroit Grand Prix - Chevrolet Detroit Grand Prix presented by Lear Fast Facts The Chevrolet Detroit Grand Prix presented by Lear was hosted on Belle Isle, May 29 - 30 2020. The event featured the cars of the NTT IndyCar Series, the IMSA WeatherTech SportsCar Championship and the Trans Am Series presented by Pirelli. The weekend is collectively referred to as the Chevrolet Detroit Grand Prix presented by Lear and it once again featured the Chevrolet Dual in Detroit IndyCar doubleheader.