The XRT4500 is a fully integrated multiprotocol serial interface. It supports all of the popular serial communication interface standards such as ITU-T V.35, ITUT V.36, EIA530A, RS232 (ITU-T V.28), ITU-T X.21 and RS449. It can easily be interfaced with most common types of Serial Communications Controllers (SCCs). This device contains eight receivers and eight transmitters, in groups of six or seven. It is a complete solution containing all of the required source and load termination resistors in one 80-pin TQFP package. The XRT4500 operates at higher speeds (20MHz for V.35 and 256kbps for V.28). The XRT4500 can be configured to operate in one of the seven interface standards in either DTE, or DCE modes of operation and power down mode. It fully supports echoed clock as well as clock and data inversion. Loopbacks are supported in DTE and DCE modes of operation. This feature eliminates the need for external circuitry for loopback implementation. Control signals such as RI, RL, DCD, DTR, DSR are protected against glitches by internal filters. These filters can be turned off. The XRT4500 provides an internal oscillator (clock signal) which can be used to conduct standalone diagnostics of DTE equipment. BLOCK DIAGRAM