A semiconductor integrated circuit includes a first clock pin controller that receives a mirror function signal and a test mode signal to generate a first input buffer control signal in response to the mirror function signal in a normal mode. A second clock pin controller receives the mirror function signal and the test mode signal to generate a second input buffer control signal, which is an inverted signal of the first input buffer control signal, in response to the mirror function signal in the normal mode. An input buffer unit generates output signals of first and second pins in response to the first input buffer control signal and the second input buffer control signal, respectively.