Patent ID: 6590787
Filing Date: 2003-07-08
Classification: H02M,Y02B

Abstract:
A switching power supply circuit, comprising:switching means including a switching device driven by a switching drive for performing a switching operation on a direct-current input voltage inputted to said switching means; a first isolating converter transformer having a primary-side winding and a plurality of secondary-side windings for transmitting an output of said switching means obtained in said primary-side winding to said plurality of secondary-side windings; a primary-side parallel resonant circuit formed by said primary-side winding and a primary-side parallel resonant capacitor for converting an operation of said switching means into a voltage-resonance-type operation; an insertable choke coil separate and apart from said first isolating converter transformer and connected in parallel with said primary-side winding for reducing an input power to said first isolating converter transformer; a secondary-side resonant circuit formed by connecting a secondary-side resonant capacitor in parallel with a first secondary-side winding of said plurality of secondary-side windings; first direct-current output voltage generating means for providing a first secondary-side direct-current output voltage by performing a rectifying operation on an alternating voltage obtained in said first secondary-side winding and inputted to said first direct-current output voltage generating means; and second direct-current output voltage generating means for providing a second secondary-side direct-current output voltage by performing a rectifying operation on an alternating voltage obtained in a second secondary-side winding of said plurality of secondary-side windings and inputted to said second direct-current output voltage generating means, and for supplying a layer load power than said first direct-current output voltage generating means.