Patent ID: 8289004

Claim:
A discharge circuit parallel connected to a PFC (power factor corrector) circuit which comprises a filter capacitor, comprising: an OC (Optical Coupler) comprising a transmitter and a receiver, wherein an input terminal of the transmitter is connected to a voltage VDD via a first diode, and an input terminal of the receiver is connected to the voltage VDD; a capacitor having an anode connected to an output terminal of the transmitter via a second diode, and a cathode connected to ground; an NPN-type transistor having a base connected to an output terminal of the receiver, an emitter connected to ground, and a collector connected to the anode of the capacitor; and a discharge unit comprising a MOSFET and a discharge resistor, a drain of the MOSFET being connected to a first terminal of the PFC circuit via the discharge resistor, a gate of the MOSFET being connected the anode of the capacitor, a source of the MOSFET being connected to ground; and a voltage dividing circuit, two terminals of the voltage dividing circuit are electrically connected to the output terminal of the transmitter of the OC and the anode of the capacitor, respectively; wherein the voltage dividing circuit comprises a first, second, third resistors, the first resistor and the second resistor being connected in series between the output terminal of the transmitter of the OC and the anode of the capacitor, a first terminal of the third resistor being connected to a connected point of the first resistor and the second resistor, and a second terminal of the third resistor being connected to ground.