Description
The Lucent Technologies Microelectronics Group T7264 U-Interface 2B1Q Transceiver integrated circuit provides full-duplex, basic-rate (2B+D) integrated services digital network (ISDN) communications on a 2-wire digital subscriber loop at either the LT or NT and conforms to the ANSI North American Standard T1.601-1992. The single +5 V CMOS device is packaged in a 44-pin plastic leaded chip carrier (PLCC).

Features
■ U-interface 2B1Q transceiver
   — Range over 18 kft on 26 AWG
   — ISDN basic-rate 2B+D
   — Full-duplex, 2-wire operation
   — 2B1Q four-level line code
   — Conforms to ANSI North American Standard T1.601-1992
   — Supports NT quiet mode and insertion loss test mode for maintenance
■ K2 interface
   — 2B+D data
   — 512 kbits/s TDM interface
   — Frame and superframe markers
   — Embedded operations channel (eoc)
   — U-interface M bits and crc results
   — Device control and status
■ Other
   — Single +5 V (±5%) supply
   — –40 °C to +85 °C
   — 44-pin PLCC
■ Power consumption
   — Operating 275 mW typical
   — Idle mode 30 mW typical
■ Analog front end
   — On-chip line driver for 2.5 V pulses
   — On-chip balance network
   — Sigma-delta A/D converter
   — Internal 15.36 MHz crystal oscillator
   — Supports 15.36 MHz external clock input
■ Digital signal processor
   — Digital timing recovery (pull range ±250 ppm)
   — Echo cancellation (linear and nonlinear)
   — Accommodates distortion from bridged taps
   — Scrambling/descrambling
   — crc calculations
   — Selectable LT or NT operation
   — Start-up sequencing with timers
   — Activation/deactivation support
   — Cold start in 3.5 seconds (typical)
   — Warm start in 200 ms (typical)
   — U-frame formatting and decoding