GENERAL DESCRIPTION
The XRT59L921 is an optimized twenty-one channel, E1, line interface unit, fabricated using low power CMOS technology. The device contains twenty-one independent E1 channels. It is primarily targeted towards the SDH multiplexers that accommodate TU12 Tributary Unit Frames. Line cards in these units multiplex 21 E1 channels into higher SDH rates. Devices with 21 E1 interfaces such as the XRT59L921 provide the most efficient method of implementing 63-channel line cards. Each channel performs the driver and receiver functions necessary to convert bipolar signals to logical levels and vice versa.

FEATURES
• Twenty-One (21) Independent E1 (CEPT) Line Interface Units (Transmitter, Receiver, and Recovery)
• Transmit Output Pulses that are Compliant with the ITU-T G.703 Pulse Template Requirement for 2.048Mbps (E1) Rates
• On-Chip Pulse Shaping for both 75Ω and 120Ω line drivers
• Detects and Clears LOS (Loss of Signal) Per ITU-T G.775
• Operates over the Industrial Temperature Range
• Ultra Low power consumption
• 3.3V operation with 5V Tolerant Input

APPLICATIONS
• PDH Multiplexers
• SDH Multiplexers
• Digital Cross-Connect Systems
• DECT (Digital European Cordless Telephone) Base Stations
• CSU/DSU Equipment