Patent ID: 7868680

Claim:
A semiconductor input/output control circuit which is an input/output control circuit provided in a semiconductor device and having a function of supplying, to a synchronous semiconductor device for performing a synchronous operation with an external clock signal, an external clock control signal indicating whether or not the external clock signal is being supplied, the semiconductor input/output control circuit comprising: a clock generation circuit for generating a basic clock signal; a control signal generation circuit for generating a clock control signal having a first logic level indicating that supply of the external clock signal is stopped and a second logic level indicating that the external clock signal is being supplied; control signal output means for outputting the external clock control signal, based on the clock control signal; a clock mask circuit for masking the basic clock signal using the clock control signal; a signal change detection circuit for detecting that a logic level of the clock control signal is changed from the first logic level to the second logic level; and clock output means for outputting the external clock signal, based on the masked clock signal which is an output from the clock mask circuit, and temporarily correcting, when the signal change detection circuit detects that the logic level of the clock control signal is changed from the first logic level to the second logic level, a waveform of the masked clock signal to output the external clock signal.