| 摘要 |
A power supply unit capable of reducing manufacturing cost by replacing regulator with zener diode is provided to output a constant voltage by applying a zener diode having constant voltage property in a auxiliary power circuit part. A power supply unit comprises a transformer(110), an auxiliary winding(120), a transistor(130), a zener diode(140), and a driving voltage output terminal(150). The auxiliary winding is wound in a primary side of the transformer. An emitter terminal of the transistor is connected to the auxiliary winding. A collector terminal of the transistor is connected to the driving voltage output terminal. A first resistor(R1) is connected between the emitter terminal and a base terminal of the transistor. A second resistor(R2) is connected to the base terminal of the transistor. An anode of the zener diode is connected to a ground terminal. A cathode of the zener diode is connected between the other terminal of the transistor and the driving voltage output terminal.
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