SEMICONDUCTOR INTEGRATED CIRCUIT

PROBLEM TO BE SOLVED: To eliminate the demerit that power is more consumed than required at the time of using a semiconductor integrated circuit with a low operating frequency in order to perform a circuit tuning to be matched with a high operating frequency. SOLUTION: A frequency to be outputted from a clock generator 101 to clock signals 112-114 is switched to a fast frequency and a slow frequency, and a signal for announcing whether the fast operating frequency or the slow operating frequency is set is outputted to frequency signal lines 142-144. Driver groups 152-154 included in a CPU 102, a memory 103, and a peripheral circuit 104 respectively receive the signal of the frequency signal liens 142-144, and when the fast operating frequency is set, the capability varying drivers are allowed to operate with first drive capability having large drive capability and large power consumption, and when the slow operating frequency is set, the drivers are allowed to operate with second drive capability having small drive capability and small power consumption. As a result, when the operating frequency is set so as to be low, the power consumption can be made lower than in proportion to the operating frequency.