| 摘要 |
PROBLEM TO BE SOLVED: To provide technique by which refreshing operation being suitable for each of plural operation states which can be taken by a semiconductor memory can be performed, and a possibility of confliction between an internal refreshment and external access can be reduced at the time of switching an operation state. SOLUTION: In an operation cycle, a memory chip 200 starts refresh-operation synchronizing with a clock signal CLK supplied from an external device after generation of a refresh-timing signal RFTM. Also, in a snooze state (low power consumption state), refresh-operation is started in accordance with the generation of the refresh-timing signal RFTM independently of existence of the clock signal CLK. When a state is shifted from the snooze state to an operation cycle, confliction between internal refreshment and external access is prevented by performing a standby cycle by one cycle before the operation cycle.
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