Patent ID: 8125799

Claim:
A switching mode power supply (SMPS), comprising: a transformer having: a primary winding; a secondary winding for providing an output voltage of the SMPS; and an auxiliary winding; a power switch coupled to the primary winding; a first control circuit coupled to the secondary winding, the first control circuit being configured to provide a first electrical signal to the secondary winding when the output voltage of the SMPS is less than a reference voltage, whereupon a second electrical signal is induced in the auxiliary winding; and a second control circuit coupled to the auxiliary winding and the power switch, the second control circuit being configured to provide a control signal to the power switch in response to the second electrical signal; and a rectifying circuit including a diode and an output capacitor, wherein the first control circuit comprises: a first terminal directly connected to the cathode of the diode and the output capacitor to receive the output voltage of the SMPS; a second terminal for directly connecting to a secondary side ground of the switching mode power supply; and a third terminal directly connected to the anode of the diode and the secondary winding; wherein the first control circuit is configured to provide a conducting path from the first terminal to the third terminal to transfer electric charges from the output capacitor to the second winding when the output voltage is less than the reference voltage.