| 摘要 |
PROBLEM TO BE SOLVED: To prevent a switching power supply from being damaged by an input excess voltage, and to suppress the withstand voltage of a switching element to a low value. SOLUTION: The switching power supply includes a rising rate calculator 18B which calculates the difference (voltage rising rate) between a voltage value of an input voltage Vi detected by an input voltage detector 18A and a voltage value detected before the previous voltage value is detected, a rising rate comparator 18C which compares a voltage rising rate with a predetermined reference rising rate. An operation stop signal setter 18E switches the operation stop signal from OFF state to ON sate, when the voltage rising rate exceeds a predetermined reference rising rate. A controller stops the switching operation of a switching element 12, when the operation stop signal is an ON state. COPYRIGHT: (C)2005,JPO&NCIPI
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