US Patent 7869235 Flyback converter having an active snubber

A flyback converter having an active snubber includes a transformer to receive input power. The transformer has a primary winding at a first side. The active snubber is coupled in parallel with two ends of the primary winding and has a first circumferential circuit coupling in parallel with the primary winding, a second circumferential circuit and a zero voltage switch unit. The second circumferential circuit is controlled by the zero voltage switch unit and incorporated with the first circumferential circuit to form double damping paths to reduce current and prevent resonance that might otherwise occur to a single circumferential circuit and the secondary side of the transformer.