Patent ID: 8427793

Claim:
A switching power supply comprising: a first switch provided between a positive terminal of a DC power supply and a positive terminal of a load; a first capacitor provided between a second switch and a node of the first switch on a DC power supply side; the second switch connected in series with the first switch, the first switch connected in parallel with the first capacitor and a second switch; a first inductor provided between the first capacitor and the positive terminal of the DC power supply; a diode connected in parallel with the second switch so that a cathode of the diode is located on the DC power supply side and is connected to a node between the second switch and the first capacitor, and an anode thereof is located on a load side; a second capacitor being provided between a node of the first inductor on the DC power supply side and a negative terminal of the DC power supply and storing a charge stored in the first capacitor; and a control circuit that turns off the second switch after the first switch is turned off and when or before a voltage across the first capacitor becomes zero.