Many electronic circuits require galvanic isolation, which typically involves the use of transformers. Numerous different topologies are employed to transmit electrical energy via a transformer. One widely used circuit type, especially for low power of approximately 50 W or less, is the flyback converter.
Figure 1 shows a schematic of a simple flyback converter. While switch S1 is on, a flyback converter stores energy in the transformer core T1. When S1 is off, the energy stored in the core is released to the output through the secondary winding of T1 through the free-wheeling diode D1.