Patent ID: 8737094

Claim:
A flyback power supply circuit comprising: an output node; a ground node; a storage capacitance coupled between the output node and the ground node; a bipolar transistor having a base, an emitter and a collector, wherein the emitter is coupled to supply charge to the storage capacitance via the output node; a diode having an anode coupled to the collector of the bipolar transistor and having a cathode coupled to the emitter of the bipolar transistor; a transformer having a primary winding, a first secondary winding, and a second secondary winding, wherein the first secondary winding has a first end and a second end, wherein the second secondary winding has a first end and a second end, wherein the first end of the first secondary winding is coupled to supply current to the base of the bipolar transistor, and wherein the first end of the second secondary winding is coupled to supply current to the collector of the bipolar transistor; and a switch coupled to conduct current through the primary winding when the switch is closed and to prevent current flow through the primary winding when the switch is open.