HC5520

S E M I C O N D U C T O R HC5520 CO/PABX Polarity Reversal Subscriber Line Interface Circuit Description The HC5520 is a Monolithic Subscriber Line Interface Circuit (SLIC) for Analog Subscriber Line cards in Central Office and PABX switches. The HC5520 provides a comprehensive set of features for these applications including loop reversal, zero crossing ringing relay operation, long loop drive and a mutually independent setting of the receive and transmit gains, and the two wire impedance synthesis. Advanced power management features combined with a small 44 lead MQFP package allow significant board space to be freed up for additional line circuits. The HC5520 is fabricated in a Harris state-of-the-art Bonded Wafer High Voltage process, providing freedom from traditional JI latch-up phenomena without the use of additional power supply filtering components or substrate tie connections. The very low parasitics and leakages associated with this process provide an exceptionally flat performance over frequency and temperature. April 1997 Features Normal and Reversed DC Feed Current Limited Loop Feed Ringing, Test-In, and Test-Out Relay Drivers Thermal Shutdown Protection with Alert Signal On-Hook Transmission Selectable Transmit and Receive Gain Setting Selectable 2-Wire Impedance Matching Zero Crossing Ring Trip Detection and Ring Relay Release Parallel Digital Control and Status Monitoring Protection Resistors Inside Feedback Loop Allows the Use of PTC Device...