Patent ID: 7623362

Claim:
A switching power supply unit, having an input terminal pair and an output terminal pair, and performing voltage conversion of a DC input voltage inputted from the input terminal pair, thereby outputting a DC output voltage from the output terminal pair, the switching power supply unit comprising: a transformer having a first winding disposed on a side of the input terminal pair, and a second winding disposed on a side of the output terminal pair, an inverter circuit disposed on a side of the first winding, and performing switching operation onto the DC input voltage, and a rectifying-smoothing circuit disposed on a side of the second winding, and rectifying and smoothing an AC voltage induced on the second winding in response to the switching operation of the inverter circuit, thereby generating the DC output voltage, wherein the second winding is configured of a plurality of conductive plates, and the rectifying-smoothing circuit has one or more rectifier elements connected between two conductive plates of the plurality of conductive plates.