| 摘要 |
PURPOSE:To raise the stability of the title device by forming a self-oscillated feedback circuit through providing a main transformer with a feedback winding and also with a saturable transformer. CONSTITUTION:A switching power circuit is grounded from the primary winding L1 of a main transformer 1 via a switching element 3 by MOS-FET, which element 3 is switched ON and OFF according to an input voltage Vin. Then, a voltage generated in a secondary winding L2 is rectified and smoothed by a diode D1 and the like and an output voltage Vout is supplied to a load. Also, the transformer 1 is provided with a feedback winding Lb, which is connected with the gate of said switching element 3 via a saturable transformer 2 to form a self-oscillated feedback circuit. Also, a Zener diode ZD1 and the like are provided between the gate and source of said element 3. Thus, because the output of said feedback winding Lb varies with the variation of input and load, the primary side current of said saturable transformer 2 varies so that a switching pulse with is increased or decreased according to a period of time until said current reaches its saturation.
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