Power converter with active clamp

A power converter comprising:

• an input side configured to receive an input voltage, and an output side configured to provide an output voltage;
• a main switch;
• a controller;
• a transformer having a primary winding that couples the main switch to the input side of the power converter;
• an active clamp switch;
• an active clamp capacitor that couples the active clamp switch to the input side of the power converter, the active clamp capacitor being coupled in a series circuit combination with the active clamp switch;
• and
• an active clamp controller circuit, the active clamp controller circuit comprising:
• a sampling circuit coupled to the main switch to receive a main switch voltage and configured to generate a sampled main switch voltage;
• a delay circuit coupled to the sampling circuit to receive the sampled main switch voltage and configured to generate a delayed sampled main switch voltage;
• a first voltage comparison circuit coupled to the sampling circuit to receive the sampled main switch voltage and coupled to the delay circuit to receive the delayed sampled main switch voltage;
• and
• an active clamp switch control circuit configured to i) enable the active clamp switch based on a first comparison, by the first voltage comparison circuit, between the sampled main switch voltage and the delayed sampled main switch voltage, and ii) disable the active clamp switch based on a second comparison, by the first voltage comparison circuit, between the sampled main switch voltage and the delayed sampled main switch voltage.