PURPOSE: To obtain a stable and high-speed turn-off characteristic even at a light load, by charging an equivalent capacity in a power MOS FET through the provision of a charging circuit.
CONSTITUTION: When a transistor TR5 is at off-state, a power MOS FET3 is conductive, while a TR41 is turned off. When the TR5 is turned on, since a gate electrode of the FET3 is grounded via a diode 6 and the TR5, the FET3 is turned off. Through the turning-on of the TR5, a base current flows from a main power supply 1 via a resistor 42 and the TR5 and the TR41 is turned on. Thus, even if the impedance of a load 2 is greater, the equivalent capacity in the FET3 can be charged through the TR41. When the TR5 turns off, the FET3 again turns on and the TR41 is turned off. Thus, the stable turn-off characteristic with high speed can be obtained independently of the load impedance.
ABE KIMIHITO
YABUNO KOUHEI
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