Patent ID: 9455623
Filing Date: 2016-09-27
CPC Classification: H02M,Y02B

Claim Text:
1. A power factor correction (PFC) circuit comprising: a first inductor operably supplied with an input voltage and an input current, the input voltage being a rectified AC line voltage; a semiconductor switch having a load current path coupled in series with the first inductor; an output terminal coupled to the first inductor and operably providing an output voltage and an output current; and a controller circuit to control a cyclic switching operation of the semiconductor switch, the controller circuit configured to: monitor a feedback signal representing a voltage drop across the load current path of the semiconductor switch; detect at least one local minimum in the feedback signal while the semiconductor switch is off; switch on the semiconductor switch in response to detecting an N-th local minimum in the feedback signal, wherein N is an integer number equal to or greater than 1 and determined dependent on at least one of the following: the input voltage, the output voltage, and the output current; and switch off the semiconductor switch after an on-time has elapsed, wherein the on-time depends on N and is adjusted, in each switching cycle, such that a cycle-by-cycle average of the input current is proportional and in-phase with the input voltage.