| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply and a semiconductor integrated circuit device that improve high-speed responsibility and efficiency. SOLUTION: A capacitor is provided between the output side and a ground potential of an inductor. A current is supplied by a first switching element from an input voltage to the input side of the inductor. When the first switching element is in an OFF state, the second switching element is turned ON to regulate the input side of the inductor to a predetermined potential. A step-up circuit forms a step-up voltage higher than the input voltage. A third switching element is provided that supplies a current from the step-up voltage to the input side of the inductor. A control circuit controls the first and second switching elements so that an output voltage obtained from the output side of the inductor becomes a desired voltage. A detection circuit detects a drop of the output voltage to a voltage lower then the desired voltage and enables the third switching element to be operated instead of the first switching element. COPYRIGHT: (C)2007,JPO&INPIT
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