Patent ID: 8299730
Filing Date: 2012-10-30
Classification: H02M,H05B,Y02B

Abstract:
1. A controller for a switched mode power supply, the controller comprising: a zero-crossing detector coupled to generate a first signal prior to a zero-crossing of an input voltage of the power supply; a drive logic to be coupled to generate a drive logic output signal in response to a feedback signal representative of an output of the power supply, wherein the drive logic output signal is representative of an initial on-time; and an on-time extension block coupled to the zero-crossing detector and the drive logic to generate a drive signal in response to the drive logic output signal, the drive signal to control switching of a switch to be coupled to the controller to remove charge from a filter capacitor of the power supply, wherein the drive signal is representative of a total on-time of the switch equal to a sum of the initial on-time and an extended on-time, wherein the extended on-time is responsive to the first signal.