Semiconductor device capable of preventing erroneous operation attributed to electrostatic noise, and input device and scanner capable of preventing electrostatic noise

Abstract

A semiconductor device includes: a plurality of external signal input means; an external input unit having a switch each connected between the external signal input means and a read line and electrically connected for output from the external signal input means on the read line; a shift register receiving an external control signal and an external clock signal and synchronized with the external clock signal to shift successively the external control signal to provide shifted data and output the external control signal to electrically connect the switches in accordance with the shifted data; an output circuit receiving the external control signal from the shift register and externally outputting the external control signal; and a frequency divider circuit dividing the external clock signal in frequency to generate and output an internal clock signal, wherein the output circuit is synchronized with the internal clock signal to externally output the external control signal.