| 摘要 |
PURPOSE:To prevent reverse flow of power from an output terminal side to a booster side by outputting an output voltage boosted by conducting and interrupting a switching element from the output terminal. CONSTITUTION:A pulse output P3 of an AND circuit 2 is input to the gate of an FET transistor 44 through an inverter 4 and a booster 70. A charged voltage V1 of a capacitor 26 is supplied the non-inverting input of an operational amplifier 72 in the booster 70. A second reference voltage Vvf2 is applied to the inverting input of the amplifier 72. The amplifier 72 produces an output Vs when the voltage V1 is larger than the voltage Vvf2 to open an AND circuit 74. A transistor 44 remains interrupted from when a voltage converter 5 is started to be initialized to when a predetermined time is elapsed after a switch 24 is closed and the voltage V1 exceeds the voltage Vvf2. Accordingly, the reverse flow of the current can be prevented during the initializing period. A desired forward current can flow to a smoothing circuit 50 through a diode 46.
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