Patent ID: 7321224

Claim:
A DC-DC converter comprising: a main switching element; an auxiliary switching element; a rectifier diode; a choke coil; an output capacitor; a clamping capacitor; a first diode connected in parallel to the clamping capacitor; and a resonance coil, wherein the resonance coil includes first and second windings, the main switching element has one terminal thereof connected to one terminal of a DC power supply and has an other terminal thereof connected to one terminal of the first winding, the choke coil has one terminal thereof connected to one terminal of the second winding and has an other terminal thereof connected to one terminal of the output capacitor, the rectifier diode has one terminal thereof connected to a connecting portion of the first and second windings and has an other terminal thereof connected to an other terminal of the output capacitor and also to an other terminal of the DC power supply, and a series circuit including the auxiliary switching element and the clamping capacitor is provided between the other terminal of the DC power supply and a connecting portion of the main switching element and the first winding, whereby a step-down operation is performed.