| 摘要 |
PROBLEM TO BE SOLVED: To prevent malfunction of a semiconductor memory by surely executing refresh operation. SOLUTION: Partial refresh information indicating permission/prohibition of refresh operation is set in accordance with external input and is output as a partial setting signal. A refresh request signal is output periodically in accordance with a memory block in which refresh operation is permitted. In order to permit refresh operation of all memory blocks during the period of time that the partial refresh information is changed by external input, the partial setting signal is masked. Thereby, even when change timing of the partial refresh information and generation timing of the refresh request signal are overlapped, prohibition of refresh operation responding to refresh request is prevented. Consequently, refresh operation can be surely executed, and malfunction of the semiconductor memory can be prevented. COPYRIGHT: (C)2009,JPO&INPIT
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