CPC G05F 1/40 (2013.01) [G05F 1/461 (2013.01); G05F 3/04 (2013.01); G05F 3/262 (2013.01)] | 4 Claims |
1. A constant voltage circuit comprising an operational amplifier including a constant current source, the operational amplifier amplifying an error between a predetermined reference voltage and an output voltage, the constant voltage circuit controlling a load current based on an amplified voltage so that the output voltage is controlled to be a predetermined constant voltage, the constant voltage circuit comprising:
a voltage detector that detects only high frequency of an AC components of the output voltage limited to a predetermined band, and outputs a detected voltage;
a voltage amplifier that amplifies AC components of the detected voltage and outputs the amplified voltage;
a judgment circuit that outputs a judgment signal indicating whether or not the amplified voltage is equal to or larger than a predetermined threshold, based on the amplified voltage; and
a controller configured to increase a current value of the constant current source of the operational amplifier based on the judgment signal, thereby temporarily increasing a current consumption of the operational amplifier.
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