Patent ID: 7460380

Claim:
A switching power converter, comprising: a transformer, comprising a primary winding having a first terminal and a second terminal, a secondary winding being coupled to an output of the switching power convener; a first transistor, connected from an input voltage to the first terminal of the primary winding; a second transistor, connected from the second terminal of the primary winding to a ground; a drive circuit, coupled to the first terminal of the primary winding and the first transistor for driving the first transistor; a charge pump circuit, connected to the drive circuit to provide a power source to the drive circuit, comprising a capacitor and a charge-pump diode, wherein the capacitor is connected to the drive circuit, and the charge-pump diode is connected from a supply voltage to the capacitor; a diode, connected from the second terminal of the primary winding to the input voltage; a third transistor, coupled from the first terminal of the primary winding to the ground; and a switching control circuit, coupled to the output of the switching power converter to generate switching signals for regulating the switching power converter, wherein the switching signals include a first switching signal and a second switching signal, the first switching signal is coupled to drive the first transistor and the second transistor, the second switching signal is coupled to drive the third transistor, and the supply voltage charges the capacitor through the charge-pump diode when the third transistor is turned on.