Patent ID: 7123488
Filing Date: 2006-10-17
Classification: H02M

Abstract:
1. A DC/DC converter comprising: a transformer having a primary winding, a secondary winding, and an auxiliary winding; a switching transistor connected in series to the primary winding of the transformer; a control transistor for turning the switching transistor on or off; and a feedback control circuit which is connected between the control transistor and the auxiliary winding of the transformer, and which includes a Zener diode having a substantially zero temperature coefficient; wherein each of the switching transistor and the control transistor is composed of an npn-type bipolar transistor, the switching transistor has a collector that is connected to an end of the primary winding and an emitter that is grounded, and the control transistor has a collector that is connected to a base of the switching transistor and an emitter that is grounded; wherein the auxiliary winding has a first end that is grounded, and the feedback control circuit is inserted between a second end of the auxiliary winding and a base of the control transistor; and wherein said feedback control circuit comprises: