Patent ID: 8004262

Claim:
A controller for use in a power factor correction (PFC) converter, comprising: an integrator coupled to receive a voltage sense signal responsive to a magnitude of an ac voltage source coupled to an input of the PFC converter coupled to an energy transfer element coupled to a power switch, the integrator further coupled to receive a current sense signal responsive to a current flowing in the power switch when the power switch is on, the integrator to generate an integrator output signal in response to the voltage sense signal and the current sense signal; and on/off logic to be coupled to drive the power switch on and off to control a transfer of energy through the energy transfer element to a load coupled to an output of the PFC converter, the on/off logic coupled to terminate an on time of the power switch when the integrator output signal reaches a threshold value, wherein a gain of the integrator is adjusted in response to the voltage sense signal such that the threshold value is substantially constant independent of the magnitude of the ac voltage source when a magnitude of the load is constant.