Patent ID: 8081496

Claim:
A power converter, comprising: an energy transfer element having an input winding coupled to an input of the power converter, an output winding coupled to an output of the power converter, and an auxiliary winding magnetically coupled to the input winding; a switch coupled to the input winding to control a transfer of energy from the input to the output of the power converter; a controller coupled to switch the switch between an ON state and an OFF state to regulate the output of the power converter, wherein the controller is adapted to terminate the ON state of the switch in response to a switch current flowing through the switch reaching a switch current threshold, and wherein the auxiliary winding is adapted to generate an auxiliary winding voltage that is representative of an input voltage of the power converter only during the ON state of the switch; and a current offset circuit coupled to the auxiliary winding to generate an offset current to flow through the switch during the ON state of the switch in response to the auxiliary winding voltage, wherein an input current of the power converter is adjusted in response to the offset current.