Patent ID: 6370040
Filing Date: 2002-04-09
Classification: H02M

Abstract:
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 at least two different outputs from the at least two secondary windings by control of the on-time of the first switching element, a rectification circuit for rectifying at least two outputs from the secondary windings and providing at least two output voltages, and an output detection circuit for detecting the at least two output voltages and providing 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, whereby the at least two different outputs from the at least two secondary windings are stabilized in dependence on a predetermined control ratio for the outputs.