| 摘要 |
PROBLEM TO BE SOLVED: To provide a control circuit for controlling a switch of a synchronous rectifier of a switch-mode power supply. SOLUTION: The switch mode power supply is provided with a switch S1 on the primary side and a transformer. The transformer is provided with a primary winding, a secondary winding WS, and an auxiliary winding WH on the secondary side. A voltage tap point P is provided between the secondary winding WS and the auxiliary winding WH on the secondary side. The control circuit 100 is connected to a connection part to the auxiliary winding WH on the secondary side and a connecting part to the voltage tap point P. The control circuit 100 is composed so as to be connected to a control terminal of the switch. The output voltage is composed so as to be tapped, in parallel with the secondary winding WS. The control circuit controls the switch on the secondary side so as to short-circuit the connection between the output terminal and the voltage tap point. Also, the control circuit controls an RC element R1, C1 so as to provide positive/negative control pulses having a prescribed time constant. The control circuit can be provided at a very reasonable price, since an RC element is used. COPYRIGHT: (C)2005,JPO&NCIPI
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