| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply circuit capable of attaining high efficiency without enlarging a circuit. SOLUTION: This power supply circuit is formed by connecting a chalk coil L1 and a switching transistor Q1 to each other in series between an input terminal 1 and grounding, connecting a serially connected circuit which consists of a coupling capacitor C3 and a chalk coil L2 to the switching transistor Q1 in parallel, connecting a rectifying diode D1 between the connecting point of the coupling capacitor C3 and the chalk coil L2 and an output terminal, and connecting a smoothing capacitor C2 between the output terminal 2 and the grounding. In the power supply circuit, a capacitive element, or a capacitor C4 is connected between the winding end on the input side of the chalk coil L1 and the cathode of the rectifying diode D1.
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