Semiconductor memory device for realizing external 8K Ref/internal 4K Ref standard without lengthening the refresh cycle

摘要

A semiconductor memory device is disclosed that realizes the external-8K Ref/internal-4K Ref standard without lengthening the refresh cycle. Successive selection and simultaneous activation of two normal word lines that do not belong to the same mat is first carried out while preventing replacement by redundant word lines by activating a redundancy non-access signal; following which successive selection and simultaneous activation of two redundant word lines that do not belong to the same mat is carried out while preventing the activation of normal word lines by activating a redundancy access signal. Since the refreshing of normal word lines and refreshing of redundant word lines are each performed while preventing replacement of normal word lines by redundant word lines, two word lines in the same mat are not simultaneously activated even though two word lines are refreshed by means of one refresh command.