Patent ID: 8552794

Claim:
A constant-voltage circuit comprising: a first reference voltage generation unit configured to generate a first reference voltage using a bandgap voltage of a bipolar transistor; a second reference voltage generation unit configured to generate a second reference voltage using a field effect transistor; a constant voltage generation unit coupled to the first and second reference voltage generation units, configured to generate a constant voltage based on either one of the first reference voltage or the second reference voltage; and a control unit configured to control the first reference voltage generation unit, the second reference voltage generation unit, and the constant voltage generation unit, the control unit having a storage unit which stores a correction value for the second reference voltage generation unit, wherein the control unit allows, during an initial activation period, the first reference voltage generation unit and the second reference voltage generation unit to operate, and then turns off the first reference voltage generation unit during an operation period after the initial activation period, wherein, during the initial activation period, the control unit, powered by the output voltage of the constant voltage generation unit generated using the first reference voltage reads the correction value stored in the storage unit and corrects the second reference voltage, and wherein, during the operation period, the constant voltage generation unit generates the output voltage using the second reference voltage.