| 摘要 |
A power supply device includes a step-up circuit configured to supply a driving voltage to a load, a comparison circuit configured to compare an output voltage from the load with a reference voltage, and a control circuit configured to control the step-up circuit based on a comparison result generated by the comparison circuit. The step-up circuit includes multiple operation modes each outputting a given voltage not lower than a power source voltage. The control circuit controls the step-up circuit to operate in one of the multiple operation modes. The control circuit maintains a current operation mode of the step-up circuit until the output voltage from the load decrease to below the reference voltage and, when the output voltage from the load is less than the reference voltage, switches the operation mode to another operation mode to output a voltage higher than a voltage output in the current operation mode.
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