| 摘要 |
PROBLEM TO BE SOLVED: To generate FET drive voltage which drives FET stably even if voltage inputted into a switching regulator fluctuates by the ripple, etc. of power source voltage. SOLUTION: A differential amplifier circuit 4 detects the voltage difference between a power source 1 and the output voltage of a switching regulator (SW-RG) 5, and inputs the voltage difference into a control terminal f. The SW-RG controls the voltage of the power source and applies it to the gate terminal G of an FET2, based on the voltage value inputted from the differential amplifier circuit. Moreover, this unit is equipped with a detection control circuit 7 which puts the potential of the control terminal f on GND level when the voltage difference between the power voltage and the output voltage of SW-RG is under a first specified threshold. In case that such a fault that the input voltage of the control terminal f of SW-RG goes high abnormally occurs and that the SW-RG controls the output voltage to be lower, a detection control circuit 7 detects the voltage difference being under a first threshold, and grounds the control terminal f. As a result, the output voltage of the SW-RG increases by the amount of the first threshold more than the power source voltage. COPYRIGHT: (C)2006,JPO&NCIPI
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