| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply unit with improved efficiency under light load. SOLUTION: In the control circuit 100 for the power supply unit 1000, a PWM modulator 10 generates a PWM signal Vpwm so that the duty ratio becomes qual to or higher than a predetermined minimum value. A first voltage comparator 20, a second voltage comparator 22, and an output unit 30 stop the driving of a switching regulator 200 during the following period: the period after the output voltage Vout' of the switching regulator 200 reaches a first threshold voltage Vth set to a value higher than a reference voltage Vref as its target value and before the output voltage drops to a second threshold voltage Vth2 (=Vref) set to a value lower than the first threshold voltage Vth. COPYRIGHT: (C)2006,JPO&NCIPI
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