OptoCoupler 16-Pin SOIC T/R
Avago’s Isolation Amplifier with Short Circuit and OverloadDetection makes motor phase current sensing compact,affordable and easy-to-implement while satisfyingworldwide safety and regulatory requirements.The HCPL-788J isolation ampli-fier is designed for currentsensing in electronic motor drives. In a typicalimplementa-tion, motor currents flow through an externalresistor and the resulting analog voltage drop issensed by the HCPL-788J. A larger analog output voltageis created on the other side of the HCPL-788J’s opticalisolation barrier. The output voltage is proportionalto the motor current and can be connected directly to asingle-supply A/D converter. A digital over-range output(FAULT) and an analog rectified output (ABSVAL). Current sensing circuitprovided. The wire OR-able over-range output (FAULT)is useful for quick detection of short circuit conditionson any of the motor phases. The wire-OR-able rectifiedoutput (ABSVAL), simplifies measure-ment of motor loadsince it performs polyphase rectification. Since the common-modevoltage swings several hundred volts in tensof nanoseconds in modern electronic motor drives, theHCPL-788J was designed to ignore very high commonmodetransient slew rates (10 kV/µs).