| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact and high power factor power supply device. <P>SOLUTION: A power supply device 10 includes: a rectification circuit 14 for rectifying an AC power supply; a first capacitor 21 for smoothing a rectified voltage; and a step-down chopper circuit 16 for supplying power to a load. The first capacitor 21 is set to such a capacitance that a half period of rectification of the AC power supply includes a section where the smoothed voltage drops to an output voltage to the load. The step-down chopper circuit 16 has a field effect transistor Q1 adapted to receive the smoothed voltage and to turn on in a section where the smoothed voltage exceeds the output voltage and turn off in a section where the output voltage is maintained, and a second capacitor 22 disposed on an output side and provided with a higher capacitance than the first capacitor 21. <P>COPYRIGHT: (C)2013,JPO&INPIT |
