| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply for preventing an output voltage from increasing without destroying internal elements even if an abnormality occurs, protecting a load supplied with the output voltage against an overvoltage, miniaturized and reducing cost. SOLUTION: The step-down switching power supply 10 outputs the voltage of a smoothing capacitor 23 as the output voltage Vout, and is provided with a FET 13 supplied with an input DC voltage Vin and switching a current flowing into a coil 22, a diode 21 for forming a current path for discharging energy stored in the coil 22 during an on-period of the FET 13, the smoothing capacitor 23 charged by the current flowing into the coil 22, a FET 15 connected between the FET 13 and the coil 22 and switched to a conducting state and an interrupting state, and an overvoltage detector 17 for interrupting the FET 15 when the output voltage Vout is detected and higher than a predetermined voltage. COPYRIGHT: (C)2006,JPO&NCIPI
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