| 摘要 |
PROBLEM TO BE SOLVED: To protect a load from an excessive voltage safely and surely without needing complicated circuit constitution, by detecting an overvoltage from the output voltage to the load and short-circuiting both ends of the load concerned, and latching the switching action thereby stopping it. SOLUTION: When the voltage of secondary winding 501, which receives power induced from the primary winding 500 of a switching transformer 5 that is provided to insulate the middle between a power input controller 3, which rectifies and smoothes AC voltage Vin from an AC power source 2, and a power output controller 4, which generates an output voltage Vout to a load 1, becomes excessive, this overvoltage is detected with an overvoltage short circuit 402, and the thyristor SCR of the overvoltage short circuit is switched on, whereby both ends P1 and P2 of the load are short-circuited. A control IC 320, which constitutes the switching control circuit 302 of the power input controller 3, detects the eddy current of the secondary winding generated by the short circuit between both ends of the load via a constant voltage control circuit 401, and latches the switching action of a transistor 301 thereby stopping it. COPYRIGHT: (C)2009,JPO&INPIT
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