The XRT5897 is an optimized seven channel 3.3V line interface unit fabricated using low power CMOS technology. The device contains seven independent E1 channels. It is primarily targeted toward SDH multiplexers that accommodate TU12 Tributary Unit Frames. Line cards in these units multiplex 21 E1 interfaces into higher SDH rates. Devices with seven E1 interfaces such as the XRT5897 provide the most efficient method of implementing 21 channel line cards. Each channel performs the driver and receiver functions necessary to convert bipolar signals to logical levels and vice versa. The device requires transformers on both receiver and transmitter sides, and supports both balanced and unbalanced interfaces.