A control circuit for use in a power converter (100A, 100B) having an energy transfer element (120A, 120B) for transferring energy between an input side and an output side of the power converter, the control circuit comprising a first controller to be coupled to the output side of the power converter, the first controller including: a switch control signal generator to be coupled to receive a feedback signal (144, 731) that is representative of an output of the power converter and configured to communicate a control signal to a second controller on the input side of the power converter via an galvanically-isolated communication link (140, 792) to initiate a transition of a switch (130, 230) on the input side of the power converter from an OFF state to an ON state to regulate the transfer of energy from the input side of the power converter to the output side of the power converter in response to the feedback signal; an extremum locator coupled to enable the switch control signal generator to communicate the control signal to the second controller in response to a first signal (123A, 123B, 223, 305, 802) that is representative of an instantaneous voltage on an output terminal of the energy transfer element that oscillates in response to an ending of the transfer of energy to the output side of the power converter, and wherein the extremum locator is configured to enable the switch control signal generator such that the transition of the switch from the OFF state to the ON state occurs substantially at a time that the oscillation of the first signal (123A, 123B, 223, 305, 802) in response to the ending of the transfer of energy to the output side of the power converter reaches an extremum; and a feedback circuit coupled to compare the feedback signal (144, 731) with a feedback threshold, wherein the switch control signal generator is configured to communicate the control signal to the second controller when enabled and if the feedback circuit indicates that the feedback signal indicates that energy is to be transferred to the output. a switch control signal generator to be coupled to receive a feedback signal (144, 731) that is representative of an output of the power converter and configured to communicate a control signal to a second controller on the input side of the power converter via an galvanically-isolated communication link (140, 792) to initiate a transition of a switch (130, 230) on the input side of the power converter from an OFF state to an ON state to regulate the transfer of energy from the input side of the power converter to the output side of the power converter in response to the feedback signal; an extremum locator coupled to enable the switch control signal generator to communicate the control signal to the second controller in response to a first signal (123A, 123B, 223, 305, 802) that is representative of an instantaneous voltage on an output terminal of the energy transfer element that oscillates in response to an ending of the transfer of energy to the output side of the power converter, and wherein the extremum locator is configured to enable the switch control signal generator such that the transition of the switch from the OFF state to the ON state occurs substantially at a time that the oscillation of the first signal (123A, 123B, 223, 305, 802) in response to the ending of the transfer of energy to the output side of the power converter reaches an extremum; and a feedback circuit coupled to compare the feedback signal (144, 731) with a feedback threshold, wherein the switch control signal generator is configured to communicate the control signal to the second controller when enabled and if the feedback circuit indicates that the feedback signal indicates that energy is to be transferred to the output.