Patent ID: 8379423

Claim:
A power factor correction circuit comprising: an inductor for receiving an input voltage and supplying output power; a power switch connected to the inductor to control an inductor current flowing through the inductor; an auxiliary inductor coupled to the inductor with a predetermined turn ratio; and a power factor correction control circuit that controls the output power by controlling the switching operation of the power switch and determines whether or not the output voltage of the output power is an over-voltage, wherein the power factor correction control circuit comprises an over-voltage protector that generates an input peak voltage corresponding to the peak of the input voltage by using a clamping current for maintaining a zero current detection voltage corresponding to an auxiliary voltage, which is a both-end voltage of the auxiliary inductor, at a predetermined clamping voltage, generates a duty voltage corresponding to the duty of the power switch, and determines whether or not the output voltage is an over-voltage according to a result of comparison between the input peak voltage and the duty voltage.