| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply capable of quickly detecting an input overvoltage and capable of stopping operation without a delay in response to the detection of the input overvoltage. SOLUTION: A DC-DC converter 40 comprises an inverter circuit 41 of a full bridge type including MOS-FETs Q1-Q4, a transformer 42, a controller 45, a monitor circuit 46 for detecting an input overvoltage, and a short circuit 47. The monitor circuit 46 and the short circuit 47 are provided on the primary side of the transformer 42. The short circuit 47 is positioned between the controller 45 and the inverter circuit 41 to short a secondary coil N<SB>24</SB>of a transformer 48 that transmits a pulse which is a base for a gate pulse in response to the detection of the input overvoltage. By this, the MOS-FETs Q1-Q4 of the inverter circuit 41 are forced to be in off-states to maintain the condition. The DC-DC converter 40 thereby stops operation. COPYRIGHT: (C)2005,JPO&NCIPI
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