| 摘要 |
PROBLEM TO BE SOLVED: To provide electronic equipment which can selectively switch a fixed frequency pulse-width modulation mode and a frequency modulation mode corresponding a loaded state, without using a voltage control oscillator (VCO) for changing frequency. SOLUTION: In a normal PWM mode, a control circuit 113 switching-controls a Hi-side switch 102 by a fixed frequency PWM signal which varies in duty ratio corresponding to the output voltage value from an error amplifier 110. Under light load, a switching control signal is generated by a power saving mode control section 127 using the output from the error lamp 110, and the Hi-side switch 102 is controlled by the frequency modulation mode. COPYRIGHT: (C)2008,JPO&INPIT
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