Quad T1/E1/J1 Transceivers

Industry's First 4-Port Transceivers to Switch Among All T1, E1, and J1 Standards without External Component Changes

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The DS21455 and DS21458 are quad monolithic devices featuring independent transceivers that can be software configured for T1, E1, or J1 operation. Each is composed of a line interface unit (LIU), framer, HDLC controllers, and a TDM backplane interface, and is controlled via an 8-bit parallel port configured for Intel or Motorola bus operations. The DS21455* is a direct replacement for the older DS21Q55 quad MCM device. The DS21458, in a smaller package (17mm CSBGA) and featuring an improved controller interface, is software compatible with the older DS21Q55.

*The JTAG function on the DS21455/DS21458 is a single controller for all four transceivers, unlike the DS21Q55, which has a JTAG controller-per-transceiver architecture.
DS21455: Block Diagram DS21455: Block Diagram Enlarge+

Key Features

Four Independent Transceivers, Each Having the Following Features:
  • Complete T1 (DS1)/ISDN-PRI/J1 Transceiver Functionality
  • Complete E1 (CEPT) PCM-30/ISDN-PRI Transceiver Functionality
  • Short- and Long-Haul Line Interface for Clock/Data Recovery and Waveshaping
  • CMI Coder/Decoder
  • Crystal-Less Jitter Attenuator
  • Fully Independent Transmit and Receive Functionality
  • Dual HDLC Controllers
  • On-Chip 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 can Connect to Asynchronous Backplanes Up to 16.384MHz
  • 16.384MHz, 8.192MHz, 4.096MHz, or 2.048MHz Clock Output Synthesized to Recovered Network Clock
  • Programmable Output Clocks for Fractional T1, E1, H0, and H12 Applications
  • Interleaving PCM Bus Operation
  • 8-Bit Parallel Control Port, Multiplexed or Nonmultiplexed, Intel or Motorola
  • IEEE 1149.1 JTAG-Boundary Scan
  • 3.3V Supply with 5V Tolerant Inputs and Outputs
  • DS21455 Directly Replaces DS21Q55
  • Signaling System 7 (SS7) Support
  • RAI-CI, AIS-CI Support


  • Channel Banks
  • Channel Service Units (CSUs)
  • Data Service Units (DSUs)
  • Muxes
  • Routers
  • Switches
  • T1/E1 Test Equipment
Product Reliability Reports: DS21458.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

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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