GENERAL DESCRIPTION
The XRT73L04B, 4-Channel, DS3/E3/STS-1 Line In terface Unit is a low power CMOS version of the XRT73L04A and consists of four independent line transmitters and receivers integrated on a single chip designed for DS3, E3 or SONET STS-1 applications.
Each channel of the XRT73L04B can be configured to support the E3 (34.368 Mbps), DS3 (44.736 Mbps) or the SONET STS-1 (51.84 Mbps) rates. Each channel can be configured to operate in a mode/data rate that is independent of the other channels.

FEATURES
• Incorporates an improved Timing Recovery circuit and is pin and functional compatible to XRT73L04A
• Meets E3/DS3/STS-1 Jitter Tolerance Requirements
• Contains a 4-Wire Microprocessor Serial Interface
• Full Loop-Back Capability
• Transmit and Receive Power Down Modes
• Full Redundancy Support
• Uses Minimum External components
• Single +3.3V Power Supply
• Low Power CMOS design
• 5V tolerant I/O
• -40°C to +85°C Operating Temperature Range
• Available in a Thermally Enhanced 144 pin LQFP package

APPLICATIONS
• Digital Cross Connect Systems
• CSU/DSU Equipment
• Routers
• Fiber Optic Terminals
• Multiplexers
• ATM Switches