| 摘要 |
A semiconductor memory device is provided to reduce failure by securing a margin of a low active time by increasing a delay time of low active time in an auto refresh operation. A precharge signal generation unit includes an auto refresh precharge pulse signal generation unit(300), an auto precharge pulse signal generation unit(400), and a signal combination unit(500). The auto refresh precharge pulse signal generation unit generates an auto refresh precharge pulse signal for delaying a low active precharge signal during one hour in a state of an auto refresh operation. The auto precharge pulse signal generation unit generates an auto precharge pulse signal for delaying the low active precharge signal during two hours in a state of an auto precharge operation. The signal combination unit receives output signals of the auto refresh precharge pulse signal generation unit and the auto precharge pulse signal generation unit and outputs the precharge signal.
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