| 摘要 |
<P>PROBLEM TO BE SOLVED: To efficiently reduce overshoot generated in relatively slow rising of a power supply voltage in association with reduction in current consumption of an electronic device. <P>SOLUTION: A constant voltage circuit for converting an input power supply voltage to a stable output voltage has: a differential amplifier circuit EA11 for comparing a feedback voltage Vf proportional to an output voltage Vo with a reference voltage Vref; a driver transistor M11 output-controlled by an output signal as a comparison result of the differential amplifier circuit EA11; and a gain control circuit (a switch circuit SW1, a transistor M21) for gradually changing a gain of the differential amplifier circuit EA11 according to the difference between a power supply voltage Vi and the output voltage Vo. The gain required according to the difference between the power supply voltage Vi and the output voltage Vo operates the differential amplifier circuit EA11 to reduce an overshoot. <P>COPYRIGHT: (C)2012,JPO&INPIT |
