| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply wherein an output voltage can be reduced to a target voltage even when the duty ratio of a PWM signal is minimized. SOLUTION: The switching power supply 1 includes: a switching element 11 that transforms the waveform of direct-current input Vi into intermittent waveform; a filter 13 that smooths the output of the switching element 11; an error amplifier 14 that generates an error signal in proportion to an error in the output voltage of the filter 13 relative to a preset target voltage; a PWM control unit 15 that generates a PWM signal based on the error signal generated by the error amplifier 14; a drive circuit 16 that switches and drives the switching element 11 according to the PWM signal generated by the PWM control unit 15; and a pulse skip unit 17 that thins out the pulse number of the PWM signal generated by the PWM control unit 15, based on the duty ratio of the PWM signal generated by the PWM control unit 15 and the error signal generated by the error amplifier 14. COPYRIGHT: (C)2010,JPO&INPIT
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