SEMICONDUCTOR DEVICE AND MEMORY SYSTEM INCLUDING THE SAME

PROBLEM TO BE SOLVED: To provide a semiconductor device capable of switching a power source voltage without causing a sharp voltage fluctuation at instantaneous interruption or in a transient state of the power source.SOLUTION: The semiconductor device includes a power supply switch and a step-down type first regulator. The semiconductor device outputs an internal power source voltage from an output terminal on the basis of an external power source voltage supplied to an input terminal. One end of the power supply switch is connected to the input terminal and the other end thereof is connected to the output terminal. The first regulator has a power terminal connected to the one end of the power supply switch and a voltage output terminal connected to the other end of the power supply switch to control the voltage at the voltage output terminal to be closer to a target voltage on the basis of the voltage at the power terminal. The target voltage is switched between a first voltage larger than the voltage at the power terminal or a second voltage smaller than the voltage at the power terminal.