| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply unit capable of improving safety and reliability to a load. SOLUTION: This switching power supply unit includes a switching transistor Q1 which is connected to a primary side main winding of an output transformer T1 having the primary main winding and a secondary winding and stabilizes a load voltage to be applied to the load. A primary sub winding T1c for controlling the switching of the transistor Q1 is provided on the output transformer T1. There is also provided an overvoltage detection circuit 3 for input power voltage provided on the primary side of the output transformer T1. Moreover, there is also provided an output cut-off circuit 4 which is provided on the secondary side of the output transformer T1 and which cuts off power supply to the load on the basis of the detected result of the overvoltage detection circuit 3. COPYRIGHT: (C)2005,JPO&NCIPI
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