A semiconductor device has a clock signal generation circuit that generates a clock signal, and a processing circuit that operates in accordance with the clock signal. The semiconductor device can also include an external terminal and a power source terminal that is coupled to the processing circuit. The clock signal generation circuit changes the frequency of the clock signal to be generated in accordance with the voltage value of a current consumption signal supplied to the external terminal. Further, the voltage value of the current consumption signal is changed in accordance with current consumption flowing in the power source terminal. The clock signal generation circuit can change the frequency of the clock signal to be generated in accordance with a value of an analog signal supplied to the external terminal.