| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power supply device wherein it is possible to stabilize a desired output voltage even when an input voltage fluctuates and to reduce ripples in this output voltage. Ž<P>SOLUTION: During a first period, only switches SW2, SW3 are turned on and a capacitor C1 is charged with input voltage VIN. A comparator 2 compares the charging voltage VC of the capacitor C1 with allowable charging voltage (VOS-VIN) and, when the charging voltage VC of the capacitor C1 becomes equal to the allowable charging voltage, outputs a charge completion signal S1. Based on the signal S1, the switches SW2, SW3 transition from on to off and charging of the capacitor C1 is stopped. The charging voltage VC of the capacitor C1 becomes equal to the allowable charging voltage. During a second period, only switches SW1, SW4 are turned on and the charging voltage VC of the capacitor C1 is added to the input voltage VIN. This added voltage becomes output voltage VOUT. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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