Description
The Lucent Technologies Microelectronics Group T7256 Single-Chip NT1 (SCNT1) Transceiver integrated circuit provides data (2B+D) and control information conversion between 2-wire (U-interface) and 4-wire (S/T-interface) digital subscriber loops on the integrated services digital network (ISDN). The T7256 conforms to the ANSI T1.601 standard and ETSI ETR 080 technical report for the U-interface and the ITU-T I.430 recommendation, ANSI T1.605 standard, and ETSI ETS 300 012 for the S/T-interface. The T7256 also supports digital pair gain and terminal adapter applications. The single +5 V CMOS device is packaged in a 44-pin plastic leaded chip carrier (PLCC).

Features
■ U- to S/T-interface conversion for ISDN basic rate (2B+D) systems
    — Integrated U- and S/T-interfaces
    — Operates in stand-alone mode to provide U- and S/T-interface activation, control, and maintenance functions
    — Serial microprocessor and time-division multiplexed (TDM) bus interfaces for enhanced NT1 operation and voice/data ports
    — Automatic embedded operations channel (eoc) processing for ANSI T1.601 systems
    — Low power consumption supporting line-powered NT1 (See table 45 on page 102, Question and Answers section, #53 for detailed power consumption information.)
    — Idle-mode support (35 mW typical)
    — Board-level testability support
■ U-interface
    — Conforms to ANSI T1.601 standard and ETSI ETR 080 technical report
    — 2B1Q four-level line code
    — Automatic ANSI maintenance functions (quiet mode and insertion loss mode)
■ S/T-interface
    — Conforms to ANSI T1.605 standard, ITU-T I.430 recommendation, and ETSI ETS 300 012 for NT operation
    — Supports point-to-point and point-to-multipoint (passive bus) arrangements
    — Supports S- and Q-channel multiframing operations (an external microprocessor is required for S- and Q-channel multiframing support)
■ Serial microprocessor and TDM bus interfaces
    — Supports inexpensive serial microprocessor
    — Supports direct codec connection and voice/ data ports
    — Allows access to 2B+D data on TDM bus
■ Other
    — Single +5 V (±5%) supply
    — –40 °C to +85 °C
    — 44-pin PLCC