Semiconductor integrated circuit

Abstract

In combining an analog terminal of an A/D converter with a digital terminal, the effect of the noise from the digital terminal is reduced. A semiconductor integrated circuit includes a high-speed external terminal, a low-speed external terminal, a high-speed analog switch, a low-speed analog switch, and an A/D converter. The high-speed external terminal is coupled to an input of the A/D converter via the high-speed analog switch, and the low-speed external terminal is coupled to the input of the A/D converter via the low-speed analog switch. A plurality of inputs of a plurality of low-speed digital input buffer circuits and a plurality of outputs of a plurality of low-speed digital output buffer circuits are coupled to a plurality of low-speed external terminals. The output of any digital output buffer circuit is not coupled to a plurality of high-speed external terminals, but a plurality of inputs of a plurality of high-speed digital input buffer circuits is coupled to a plurality of high-speed external terminals. Between a plurality of low-speed external terminals and the input of the A/D converter, a low-speed separating resistor with a high resistance value is coupled, respectively.