| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power unit which can stop the output based on the overcurrent detection signal of an overcurrent detecting circuit which detects the overcurrent of a switching element even if any secondary winding of a transformer equipped with a plurality of secondary windings short-circuits. SOLUTION: The switching of the switching element 4 which controls the supply of DC power to the primary winding 2 of the transformer T is controlled by a control circuit 7. When the overcurrent detection signal of the overcurrent detecting circuit 5 which detects the overcurrent of the switching element 4 is inputted into the control circuit 7, the drive of the switching element 4 is stopped. The transformer 7 is equipped with a plurality of secondary windings 6a and 6b for output, and the ON and OFF of the switching element 4 are controlled so that the output voltage of the winding 6a for control comes to a specified value. The winding 6a for control is provided so that the coupling to the primary winding 2 is the worst between the plurality of secondary windings 6a and 6b.
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