| 摘要 |
PROBLEM TO BE SOLVED: To provide a power factor improving circuit which can reduce a size and a noise and which increases an efficiency by reducing the power loss of a portion having a low AC power supply voltage. SOLUTION: The power factor improving circuit improves an input power factor by turning on/off via a main switch Q1 by inputting a rectified voltage obtained by rectifying the AC power supply voltage of an AC power supply Vac1 by a full-wave rectifying circuit B1 via a step-up reactor L1 and converts the rectified voltage into a DC output voltage. The power factor improving circuit includes a control circuit 10 for controlling the switching frequency (f) of the main switch Q1 in response to an AC power supply voltage value. COPYRIGHT: (C)2005,JPO&NCIPI
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