| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power circuit capable of avoiding shutdown due to insufficient charging time of a floating power supply voltage, using a simple circuit configuration. SOLUTION: The difference between an input voltage from a DC power supply V2 and a switching output voltage of FET1 charges a voltage clamped by a Zener voltage of a Zener diode D5 into a capacitor C6 of a backup power circuit 4. The electricity charged into a capacitor C1 is consumed by the switching operation of FET1; and when the voltage of the capacitor C1 is lower than a predetermined voltage, a diode D3 is turned on, and power is fed from the capacitor C6 to a gate drive circuit 2. COPYRIGHT: (C)2007,JPO&INPIT
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