Patent ID: 7501800
Filing Date: 2009-03-10
Classification: G05F,H02M,Y02B

Abstract:
1. A power factor correction circuit comprising: a boost circuit having a switch coupled to an input terminal and supplying an output voltage to an output terminal according to an operation of the switch; and a switching controller for generating a reference voltage according to the output voltage provided to the output terminal of the boost circuit for a predetermined delay time after an input AC voltage is applied to the input terminal of the boost circuit, and for controlling the switch according to the generated reference voltage and the input AC voltage, wherein the switching controller comprises: a first comparator for comparing a voltage that corresponds to the output voltage during the delay time with a first comparator reference voltage and for outputting a corresponding first comparator voltage; a voltage generator for generating the reference voltage with a first level or a second level depending on a level of the first comparator voltage; a second comparator for comparing the reference voltage and a voltage that corresponds to the output voltage and for outputting a second comparator voltage; a multiplier for multiplying the second comparator voltage and a voltage that corresponds to the input AC voltage applied to the input terminal of the boost circuit; and a pulse width modulation circuit for controlling the switch according to an output of the multiplier.