Switching power supply apparatus

A switching power supply apparatus comprising a transformer having a primary winding and at least two secondary windings, a first switching element having an on-time and an off-time, the first switching element connected in series with the primary winding, a control circuit for controlling an output from the first switching element by control of the on-time thereof, a rectification circuit for rectifying at least two outputs from the secondary windings and providing output voltages and an output detection circuit for detecting the output voltages and feeding back the output voltages as a control signal for control of the on-time to the control circuit,

• wherein the output voltage detection circuit comprises a control signal formation circuit in which the control signal for control of the on-time is formed, corresponding to a voltage at a voltage comparison terminal, and plural voltage detectors connected between the at least two outputs of the secondary windings and the voltage comparison terminal, respectively.