Patent ID: 8362790

Claim:
An alternating current (AC) detection circuit, comprising: a rectifying part for rectifying an AC voltage; a voltage division part for dividing the voltage rectified by the rectifying part according to a preset division ratio; a voltage stabilization circuit part for stabilizing the voltage divided by the voltage division part; a comparing part for comparing the voltage stabilized by the voltage stabilization circuit part with an internal reference voltage and generating an input detection signal when the stabilized voltage is higher than the internal reference voltage; and an output part for outputting first and second AC detection signal signals when the input detection signal is inputted from the comparing part, wherein the comparing part comprises a shunt regulator including: a cathode connected to the output part; an input port connected to an output port of the voltage stabilization circuit part; and an anode connected to a ground, the output part comprises a first output part and a second output part, the first output part comprises an NPN transistor including: a base connected to the cathode of the shunt regulator; a collector connected to the second output part and a first output port for outputting the first AC detection signal; and an emitter connected to the ground, and the second output part is configured as a photocoupler comprising: an anode connected to receive a first operation voltage and concurrently connected to a second output port for outputting the second AC detection signal; a photodiode connected to the collector of the NPN transistor; and a phototransistor including a collector connected to receive a second operation voltage, a base for receiving light from the photodiode, and an emitter connected to the ground.