Patent ID: 7382635

Claim:
A power supply apparatus comprising: an input terminal arranged to be connected to a direct-current (DC) power supply; a DC-DC converter having an output port and an input port connected to the input terminal; a first capacitor; a second capacitor; a first output terminal; a first switch connected between the output port of the DC-DC converter; a second switch connected between the first capacitor and the first output terminal; a third switch connected between the output port of the DC-DC converter and the second capacitor; a fourth switch connected between the second capacitor and the first output terminal; and a switch controller operable to turn off the second switch while turning on the first switch as to charge the first capacitor, turn off the first switch while turning on the second switch as to discharge the first capacitor, turn off the fourth switch while turning on the third switch as to charge the second capacitor, turn off the third switch while turning on the fourth switch as to discharge the second capacitor, charge the first capacitor and the second capacitor alternately charged, discharge the first capacitor and the second capacitor alternately, turn off at least one of the third switch and the fourth switch while turning on the second switch, turn off at least one of the first switch and the second switch while turning on the fourth switch, and prevent the output port of the DC-DC converter from being connected to the first output terminal.