XRT81L27

áç XRT81L27 NOVEMBER 2001 SEVEN CHANNEL E1 LINE INTERFACE UNIT WITH CLOCK RECOVERY REV. 1.1.0 GENERAL DESCRIPTION The XRT81L27 is an optimized seven-channel, analog, 3.3V, line interface unit, fabricated using low power CMOS technology. The device contains seven independent E1 channels, including data and clock recovery circuits. 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 seven E1 interfaces such as the XRT81L27 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 receiver input accepts transformer or capacitor coupled signals, while the transmitter is coupled to the line using a 1:2 step-up transformer. The same transformer configuration can be used for both balanced 120 Ω and unbalanced ...