T7689

The T7689 is a fully integrated quad line interface containing four transmit and receive channels for use in North American (T1/DS1) applications. The device has many of the same functions as the Lucent Technologies Microelectronics Group T7290A and provides additional flexibility for the system designer.

Included is a parallel microprocessor interface that allows the user to define the architecture, initiate loopbacks, and monitor alarms. The T7689 interface is compatible with many commercially available microprocessors.

The receiver performs clock and data recovery using a fully integrated digital phase-locked loop. This T7689 conditions that are common when recovering sparse data patterns with analog phase-locked loops. Equalization circuitry in the receiver guarantees a high level of interference immunity. As an option, the raw sliced data (no retiming) can be output on the receive data pins.

Transmit equalization is implemented with lowimpedance output drivers that provide shaped waveforms to the transformer, guaranteeing template conformance. The quad T7689 device will interface to the digital cross connect (DSX) at lengths of up to 655 ft. for DS1 operation.

A selectable jitter attenuator may be placed in the receive signal path for low-andwidth linesynchronous applications, or it may be placed in the transmit path for multiplexer applications where DS1 signals are demultiplexed from higher rate signals. The jitter attenuator will perform the clock smoothing required on the resulting demultiplexed gapped clock.