Patent ID: 7375987

Claim:
A resonant switching power source apparatus comprising: a first switching element and a second switching element that are connected in series between output terminals of a DC power source and are alternately turned on and off; a series resonant circuit having a primary winding of a transformer and a current resonance capacitor and connected in parallel with the second switching element; a controller configured to control ON/OFF operation of the first and second switching elements; a rectifying/smoothing circuit configured to rectify and smooth a voltage, which is generated on a secondary winding of the transformer during an ON period of the second switching element controlled by the controller, and output the rectified-smoothed voltage; and a current detector configured to detect a current passing through the series resonant circuit; and an over current protector of the controller configured to turn off the first and second switching elements for a predetermined period to reset excitation energy of the transformer as the current detector detects a predetermined current value.