Semiconductor device used in step-up DC-DC converter, and step-up DC-DC converter

摘要

A power supply device is disclosed that is able to satisfy the power requirements of a device in service and has high efficiency. The power supply device includes a first power supply; a voltage step-up unit that steps up an output voltage of the first power supply; a voltage step-down unit that steps down an output voltage of the voltage step-up unit; and a load that is driven to operate by an output voltage of the voltage step-down unit. The voltage step-up unit steps up the output voltage of the first power supply to a lower limit of an operating voltage of the voltage step-down unit.