VOLTAGE SELECTION CIRCUIT AND SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE HAVING THE SAME

摘要

The highest voltage of a power supply voltage, a ground potential, and a signal voltage is output as a selection voltage from a terminal on the output side. In this case, terminals on the input side and the terminal on the output side are connected to each other through MOS transistors in the ON state. Therefore, it is possible to suppress a voltage drop due to a parasitic diode of each MOS transistor.

主权项

1. A voltage selection circuit that selects a highest voltage of a plurality of voltages, comprising:
a first terminal to which a first voltage is input; a second terminal to which a second voltage is input; a third terminal to which a third voltage is input; a fourth terminal from which a highest voltage of the first voltage, the second voltage, and the third voltage is output; a P-type first MOS transistor connected between the first and fourth terminals; a P-type second MOS transistor connected between the second and fourth terminals; a P-type third MOS transistor connected between the third and fourth terminals; a first resistor connected between a gate of the first MOS transistor and the second terminal; a second resistor connected between a gate of the second MOS transistor and the first terminal; a voltage output circuit that outputs a higher voltage of the first and second voltages to a gate of the third MOS transistor; and a switching circuit that connects the third terminal to the gates of the first and second MOS transistors when the third voltage is higher than an output voltage of the voltage output circuit, wherein the first MOS transistor, the second MOS transistor, the third MOS transistor, a P-type MOS transistor included in the voltage output circuit, and a P-type MOS transistor included in the switching circuit have bulks connected to the fourth terminal.