POWER SUPPLY

PROBLEM TO BE SOLVED: To reduce the number of components, a cost and an implementation space in a power supply for dealing with a mode (a standby mode) for requiring low standby power and a mode for requiring a large output load, and also dealing with a relatively large load such as a load of 50 W or more required in the mode for requiring the low standby power. SOLUTION: The power supply has a rectifying circuit for rectifying a commercial power supply, a first power supply circuit for supplying an output DC voltage from the rectifying circuit to a voltage converting circuit through a power factor improving circuit and outputting a DC voltage from an output of the voltage converting circuit, and a second power supply circuit comprising a power factor improving converter circuit for improving a power factor of the output DC voltage from the rectifying circuit and converting the output DC voltage. An input voltage smoothing capacitor of the voltage converting circuit in the first power supply circuit is commonly used for an input voltage smoothing capacitor in the second power supply circuit. COPYRIGHT: (C)2006,JPO&NCIPI