Patent ID: 6975521

Claim:
A switching power supply apparatus, comprising: a primary side via which alternating current power is received and a secondary side with an output via which switched power is output; a primary side rectifying circuit operatively configured to rectify alternating current power received via said primary side and to generate rectified current power; a starting circuit operatively provided at the primary side and operatively coupled to receive said rectified current power generated by said primary side rectifying circuit; a switching element; a switching control circuit operatively coupled to the starting circuit and having an output coupled to the switching element; a hysteresis low voltage malfunction preventing circuit operatively configured and coupled to prevent low voltage malfunction of said switching control circuit; a converter transformer with primary, secondary and tertiary windings, with said primary winding having one end coupled to said primary rectifying circuit and another end couple to said switching element; a first rectifying/smoothing circuit operatively configured to rectify and smooth current output from said tertiary winding and to supply its output to said switching control circuit; a photo-coupler having an output coupled to a feedback input of said switching control circuit; a second rectifying/smoothing circuit coupled between said secondary winding and a power input of said photo-coupler; an output detecting circuit coupled between said secondary side and said photo-coupler and having an input coupled to detect power at said secondary side output; and a secondary side rectifying/smoothing circuit coupled between said secondary winding and said secondary side output, said output detecting circuit having a power input operatively coupled to said secondary side rectifying/smoothing circuit to receive power therefrom, wherein, drive power is delivered to the photo-coupler by said second rectifying/smoothing circuit for driving the photo-coupler, and drive power is delivered to the output detecting circuit by said secondary side rectifying/smoothing circuit for driving the output detecting circuit.