Patent ID: 7218535

Claim:
A DC conversion apparatus comprising: a first switch configured to carry out ON/OFF operations via a primary winding of a transformer to convert a DC voltage provided by a DC power source into high-frequency voltage; a synchronous rectifying circuit configured to carry out synchronous rectification of a high-frequency voltage generated at a secondary winding of the transformer; a smoothing circuit having a smoothing reactor and a smoothing capacitor configured to smooth a rectified output of the synchronous rectifying circuit and to output a DC voltage; a storage capacitor configured to store energy being stored in the smoothing reactor and transferred thereto via a diode due to a current backflow of the synchronous rectifying circuit flowing under a light load condition; a second switch configured to turn ON in synchronization with the first switch and to return the energy stored in the storage capacitor to the DC power source at a primary side of the transformer via the transformer; and a control circuit configured to turn ON/OFF the first switch.