| 摘要 |
PURPOSE: A driving and feedback circuit of switch mode power supply is provided to remove a generation of heat and feedback noise in supplying a pulse by using a pulse control system. CONSTITUTION: A driving and feedback circuit of switch mode power supply comprises a capacitor(10), a voltage dividing part(20), a transformer(30), a Field Effect Transistor (40), a pulse input part, an overcurrent limiting part(600), a first rectifying part(700), a second rectifying part(900), and a photo coupler(80). The capacitor(10) rectifies an AC voltage to transmit a DC voltage. The voltage dividing part(20) divides into a predetermined voltage to input the DC voltage transmitted through the capacitor(10). The transformer (20) is composed of a primary winding, a secondary winding and a third winding. The primary winding receives an input of DC current transmitted through the capacitor to transmit a voltage. The secondary winding receives an input of the DC current transmitted through the primary winding to maintain the voltage. The third winding receives an input of the DC voltage transmitted through the primary winding. The FET(40) is switched by the current inputted through the primary winding of the transformer and the voltage dividing part. The pulse input part inputs a pulse to run the FET. The overcurrent limiting part(600) limits an overcurrent produced by the FET through the secondary winding of the transformer.
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