| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-power consumption constant voltage circuit for responding to a small variation in an output voltage and an electronic apparatus equipped therewith. SOLUTION: The constant voltage circuit is provided with an output transistor M1 connected between an input voltage Vdd and an output voltage Vo; and an error amplifying circuit 11 receiving an input of a voltage obtained by dividing a reference voltage Vref and an output voltage Vo, amplifying the difference of them, and outputting the input, and controls the output transistor M1 by the output of the error amplifying circuit 11; an output voltage variation detection circuit 12 for detecting the variation of the output voltage Vo; and a bias current amplifying circuit 13 for increasing a bias current of the error amplifying circuit 11. The bias current amplifying circuit 13 is operated by the output of the output voltage variation detection circuit 12 during the variation of the output voltage Vo, and the bias current of the error amplifying circuit 11 is increased to achieve high speed operation. The output voltage variation detection circuit 12 may be provided with both or either of a comparator 21 useful in a voltage rise and/or a comparator 22 useful in a voltage fall. COPYRIGHT: (C)2008,JPO&INPIT
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