Power-supply apparatus

Discloses a via one or more switching elements for output voltage of the power supply device. The apparatus comprising: a voltage generating circuit, a voltage proportional to the input terminal and between the output terminal generating an output voltage Vo of the switching element; and a control circuit for the output voltage Vo of, the control operation of the switching element. When the output voltage Vo exceeds the predetermined voltage Vs, the control circuit causes the switching element to reduce an output current.