| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply with high precious overvoltage protection function having no malfunction. SOLUTION: In an overvoltage detection adjusting circuit 6 connected to an auxiliary winding 1c, a signal of an AC voltage is generated which is proportional to a voltage component obtained by removing a ringing component of the AC voltage induced in the auxiliary winding 1c, and in an overvoltage detection circuit 17, the signal for stopping on/off operation of a switching element 2 is generated to reduce an output DC voltage Vout when an overvoltage state is detected in which a peak value of the signal of the AC voltage generated by the overvoltage detection adjusting circuit 6 becomes a fixed value or more. COPYRIGHT: (C)2009,JPO&INPIT
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