GENERAL DESCRIPTION
The DS2156 is a software-selectable T1, E1, or J1 single-chip transceiver (SCT) for short-haul and long-haul applications. The backplane is userconfigurable for a TDM or UTOPIA II bus interface. The DS2156 is composed of a line interface unit (LIU), framer, HDLC controllers, and a UTOPIA/TDM backplane interface, and is controlled by an 8-bit parallel port configured for Intel or Motorola bus operations. The DS2156 is pin and software compatible with the DS2155.

FEATURES
■ Complete T1/DS1/ISDN-PRI/J1 Transceiver Functionality
■ Complete E1 (CEPT) PCM-30/ISDN-PRI Transceiver Functionality
■ User-Selectable TDM or UTOPIA II Bus Interface
■ 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

APPLICATIONS
    Inverse Mux ATM (IMA)
    T1/E1/J1 Line Cards
    Switches and Routers
    Add-Drop Multiplexers