US Patent 11695343 Output-side controller with switching request at relaxation ring extremum

A control circuit comprising an output controller coupled to an output side of a power converter. The output controller comprises a switch control signal generator to receive a feedback signal representative of an output of the power controller and to communicate a control signal to an input controller coupled to an input side to control a turn ON of a power switch. The control signal is generated in response to the feedback signal and is communicated in response to an enable signal. The output controller comprises an extremum locator to generate the enable signal in response to a winding signal representative of an instantaneous voltage on an output terminal of an energy transfer element and the extremum locator enables the switch control signal generator such that the transition of the power switch from the OFF state to the ON state occurs substantially when the winding signal reaches an extremum.