Patent ID: 7876637

Claim:
A semiconductor device, comprising: a first step-down voltage circuit that generates a first step-down voltage and provides the first step-down voltage to a first power supply line, the first step-down voltage being lower than a power supply voltage; a plurality of second step-down voltage circuits connected to the first power supply line, each of said second step-down voltage circuits generating a second step-down voltage lower than the first step-down voltage; and a switching circuit to select and supply one of either the power supply voltage or the first step-down voltage to the second step-down voltage circuits, wherein the first step-down voltage circuit has a withstand voltage equal to or higher than the power supply voltage, wherein the second step-down voltage circuit has a withstand voltage equal to or higher than the first step-down voltage, wherein the first step-down voltage circuit comprises a transistor having an oxide film with a first thickness, and wherein each of the second step-down voltage circuits comprises a transistor having an oxide film thinner than the first thickness.