Secondary controller for use in synchronous flyback converter

A secondary controller for a synchronous flyback converter, the secondary controller comprising:

• a clamped forward voltage circuit coupled to respond to an input signal indicative of a voltage on a secondary winding of the synchronous flyback converter and configured to generate a clamped forward voltage signal;
• a comparator, coupled to generate a compare signal in response to a comparison of a threshold and the clamped forward voltage signal;
• a drive circuit configured to generate a drive signal in response to a feedback signal representative of an output of the synchronous flyback converter;
• a first switch, having an ON state, the first switch coupled to a primary side of the synchronous flyback converter to respond to the drive signal;
• logic circuitry coupled to generate a control signal in response to the drive signal and the compare signal;
• and
• a second switch, having an ON state, the second switch coupled to the secondary side of the synchronous flyback converter to respond to the control signal,
• wherein the logic circuitry is configured to ensure that the first switch and the second switch are not simultaneously in their respective ON states.

A synchronous flyback converter, comprising:

• an energy transfer element having a primary winding and a secondary winding;
• a first switch, having an ON state, the first switch coupled to the primary winding and coupled to an input of the synchronous flyback converter;
• a second switch, having an ON state, the second switch coupled to a secondary side of the synchronous flyback converter;
• and
• a secondary controller coupled to the first switch, configured to control a transfer of energy through the energy transfer element from the input of the synchronous flyback converter to an output of the synchronous flyback converter, the secondary controller including:
• a clamped forward voltage circuit, coupled to respond to an input signal indicative of a voltage on a secondary winding of the synchronous flyback converter and configured to generate a clamped forward voltage signal;
• a comparator coupled to generate a compare signal in response to a comparison of a threshold to the clamped forward voltage signal,
• a drive circuit coupled to generate a drive signal to control the first switch, wherein the drive signal is generated by the drive circuit in response to a feedback signal representative of the output of the power converter, and
• logic circuitry, coupled to the drive circuit and the comparator, the logic circuitry configured to generate a control signal to control the second switch in response to the drive signal and the compare signal,
• wherein the logic circuitry is configured such that the first switch and the second switch are not simultaneously in their respective ON states.