| 摘要 |
PROBLEM TO BE SOLVED: To stably drive an FET irrespective of a variation in power supply voltage. SOLUTION: A voltage difference between a first voltage value of a power supply 1 and an output voltage value of a switching regulator 5 is calculated by a differential amplification circuit 4, and the voltage difference is divided in terms of voltage by resistors 15, 16 and entered into the switching regulator 5. The switching regulator 5 compares the voltage value entered from the differential amplification circuit 4 with a reference voltageβ, controls the voltage of the power supply 1 and applies it to a gate terminal of the FET 2. By this arrangement, the output voltage value of the switching regulator 5 varies in accordance with a variation in the voltage value of the power supply 1, a voltage between terminals of a gate and a source of the FET 2 is always stable, and thus the FET 2 can be driven while keeping a desired voltage between the terminals of the gate and the source. COPYRIGHT: (C)2005,JPO&NCIPI
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