Patent ID: 7911259

Claim:
A voltage switching circuit for selecting a voltage from among a plurality of input voltages in response to a combination of control signals and outputting the selected voltage from an output terminal, the voltage switching circuit comprising: a first PMOS transistor for outputting a power supply voltage for operating a logic circuit of a semiconductor device to the output terminal; a second PMOS transistor for outputting a first voltage higher than the power supply voltage to the output terminal; a third PMOS transistor for outputting a second voltage lower than the power supply voltage to the output terminal; and a well potential control section for controlling a well voltage of the first transistor and a well voltage of the third transistor to be the power supply voltage when either the power supply voltage or the second voltage is supplied to the output terminal, and controlling the well voltage of the first transistor and the well voltage of the third transistor to be the first voltage when the first voltage is supplied to the output terminal.