Patent ID: 8189354

Claim:
A voltage converter which converts an input voltage into an output voltage for driving a load, the voltage converter comprising: an input end for receiving the input voltage; an output end for outputting the output voltage; a first electromagnetic device configured to generate a corresponding first current according to the input voltage, the first electromagnetic device comprising: a first end coupled to the input end; and a second end; a second electromagnetic device having a first end and a second end for inducing a voltage corresponding to the first current and providing a second current associated with the output voltage; a power switch device coupled to the second end of the first electromagnetic device for controlling a signal transmission path between the second end of the first electromagnetic device and a power supply node according to a switch control signal; a snubber circuit coupled between the first end of the first electromagnetic device and the power supply node for storing a leakage inductance energy of the first electromagnetic device and providing a zero-current signal associated with the second current, the snubber circuit comprising: a first capacitor including: a first end coupled to the second end of the first electromagnetic device; and a second end; a third electromagnetic device including: a first end coupled to the power supply node; and a second end; a first diode having an anode coupled to the second end of the first capacitor and a cathode coupled to the input end; and a second diode having an anode coupled to the second end of the third electromagnetic device and a cathode coupled to the second end of the first capacitor; and a switch control unit for generating the switch control signal according to a feedback signal and the zero-current signal.