Patent ID: 7123067

Claim:
A voltage-change control circuit comprising: a booster circuit section for boosting an input voltage; a drive circuit section for supplying a driving clock to the booster circuit section; a voltage detecting section for detecting a level of a boost voltage outputted from the booster circuit section; and a control circuit section for changing a clock amplitude of the drive circuit section in accordance with a detection result by the voltage detection section; wherein the control circuit section comprises a control amount determining section for shifting a control amount for changing the clock amplitude; and the control amount determining section has an up/down counter for increasing and decreasing a count value for shifting the control amount to vary the clock amplitude in accordance with the detection result from the voltage detecting section, and a D/A converter for determining the control amount to vary the clock amplitude on the basis of the count value by the up/down counter, and for supplying the control amount to the a level shifter section, said level shifter section supplying a feedback signal to the drive circuit section.