Patent ID: 8040114

Claim:
A controller for use in a power factor correction (PFC) converter, comprising: a first integrator coupled to integrate an input current of the PFC converter, wherein a first signal is generated in response to the first integrator to end an on time of a power switch of the power converter; a second integrator coupled to integrate a difference between a constant voltage and an input voltage of the PFC converter, wherein a second signal is generated in response to the second integrator to end an off time of the power switch; a driver circuit coupled to vary the switching frequency of the power switch in response to the first and the second signals and to output a third signal to switch the power switch to control the input current to be substantially proportional to the input voltage; and a frequency adjust circuit coupled to receive an error voltage signal representative of a load at an output of the PFC converter, wherein the frequency adjust circuit is further coupled to output an adjusted error signal to adjust the end of the off time of the power switch in response to the error voltage signal.