The XRT83SL30 is a fully integrated single-channel short-haul line interface unit for T1(1.544Mbps) 100Ω, E1(2.048Mbps) 75Ω or 120Ω and J1 110Ω applications. In T1 applications, the XRT83SL30 can generate five transmit pulse shapes to meet the short-haul Digital Cross-Connect (DSX-1) template requirements. The XRT83SL30 provides both Serial Host microprocessor interface and Hardware Mode for programming and control. Both B8ZS and HDB3 encoding and decoding functions are included and can be disabled as required. On-chip crystal-less jitter attenuator with a 32 or 64 bit FIFO can be placed either in the receive or the transmit path with loop bandwidths of less than 3Hz. The XRT83SL30 provides a variety of loop-back and diagnostic features as well as transmit driver short circuit detection and receive loss of signal monitoring. It supports internal impedance matching for 75Ω, 100Ω, 110Ω and 120Ω for both transmitter and receiver. For the receiver this is accomplished with internal resistors or through the combination of one single fixed value external resistor and programmable internal resistors. In the absence of the power supply, the transmit output and receive input are tri-stated allowing for redundancy applications. The chip includes an integrated programmable clock multiplier that can synthesize T1 or E1 master clocks from a variety of external clock sources.