A semiconductor device including an internal terminal, a first transistor of a first conductivity type that is coupled between a first reference potential and the internal terminal, and that includes a first control terminal, a second transistor of a second conductivity type that is coupled between a second reference potential and the internal terminal, and that includes a second control terminal, an oscillator that includes an output terminal to output a clock signal, and a comparator that is coupled to the internal terminal, and that compares a potential of the internal terminal when the internal terminal is coupled to the first reference potential with a potential of the internal terminal when the internal terminal is coupled to the second reference potential. Each control terminals is coupled to the output terminal to commonly receive the clock signal, and the first and second transistors exclusively operate in response to the clock signal.