Switching power supply apparatus

A switching power supply apparatus providing an output voltage comprising a transformer having a primary winding and a secondary winding, a first switching element having an on-time and an off-time, the first switching element connected in series with the primary winding, a first control circuit for controlling the on-time of the first switching element whereby the output voltage is controlled, and a rectification circuit for rectifying an output from the secondary winding, whereby input voltage is applied to the primary winding during the on-time of the first switching element and causes current to flow in the primary winding so that energy is stored in the transformer, and the energy stored in the transformer is released as electric current from the secondary winding when the first switching element is turned off, and the current is rectified in the rectification circuit to obtain said output voltage,

• wherein the rectification circuit comprises a rectification diode, a second switching element connected in parallel to the rectification diode, a second switching element drive winding provided in the transformer to generate an output voltage which causes the second switching element to be turned on, and a second control circuit for turning on the second switching element by use of a voltage from the second switching element drive winding, and turning off the second switching element after a time determined by a time constant, a further switching element being connected to the control terminal of the second switching element for turning off the second switching element after the time.