HIGH-SENSITIVITY CONTROL CIRCUIT FOR OPTICAL SEMICONDUCTOR RELAY

摘要

PROBLEM TO BE SOLVED: To suppress a necessary turn-on current low by improving the switching speed of a control circuit for an optically coupled semiconductor relay. SOLUTION: A high-sensitivity control circuit 20 for the semiconductor relay of an optically coupled semiconductor relay circuit 10 equipped with a light emission diode 14 operates a switching transistor for a photodiode array to reduce the loading effect of a turn-off circuit for the photodiode array which switch input signals to switching contacts 22 to 26. Further, a two-stage CMOS amplifier is used to perform high-speed switching operation. The inactivation of the light emitting diode 14 biases a sense photodiode reversely to discharge a switching transistor, thereby preventing the input signals from being switched to the switch contacts.