Patent ID: 7629781

Claim:
A multi-output switching power supply comprising: a first switching element and a second switching element which are connected in series between output terminals of a DC power supply; a series resonant circuit which is connected in parallel with one of the first and second switching elements, and includes a current resonance capacitor, a resonant reactor and a primary winding of a transformer, which are connected in series; a first rectifying and smoothing circuit which rectifies and smoothes a voltage generated in a secondary winding of the transformer, and thus outputs a first output; a second rectifying and smoothing circuit which has a first diode for rectifying the voltage generated in the secondary winding of the transformer, one end of the first diode is connected to one end of the secondary winding of the transformer, a reactor having energy stored therein by the voltage rectified by the first diode in the secondary winding, one end of the reactor is connected to other end of the first diode, other end of the reactor is connected to other end of the secondary winding of the transformer and one end of a first output terminal, and a second diode for regenerating the energy stored in the reactor into an output, one end of the second diode is connected to the other end of the first diode and the one end of the reactor, other end of the second diode is connected to other end of the first output terminal, and which rectifies a current flowing through the reactor and outputs a second output to the one end and the other end of the first output terminal; and a control circuit which alternately turns on and off the first and second switching elements based on the first output obtained by the first rectifying and smoothing circuit.