发明名称 |
Semiconductor memory device facilitated with plural self-refresh modes |
摘要 |
The semiconductor memory is facilitated with control circuitry for effecting plural self-refresh modes having respectively different refresh periods. The plural self-refresh modes are typified by a PS (pseudo) refresh mode which is applied when the memory is in the nonselected state for a comparatively long period of time, such as in the state in which memory backup is being facilitated, and by a VS (virtual) refresh mode in which the refreshing operation of the memory cells is effected intermittently during the intervals of memory accessings. The pseudo refresh mode has a longer refresh time period than the virtual refresh mode. The control circuitry also has counter circuits for the generating of refresh address signals in accordance with a first timing signal indicative of a pseudo refresh mode and a second timing signal indicative of a virtual refresh mode, the latter timing signal being a higher frequency signal. Such availability of plural self-refresh modes becomes particularly advantageous when considering consumption of the back-up power for maintaining the IC memory device versus stability of stored data. While the consumption of the back-up power for maintaining the device would be relatively lower under one of the self-refresh modes, namely, the PS (pseudo) refresh mode, the stability of data stored would, however, be greater under another self-refresh mode, namely, the VS (virtual) refresh mode. |
申请公布号 |
US5467315(A) |
申请公布日期 |
1995.11.14 |
申请号 |
US19940234414 |
申请日期 |
1994.04.28 |
申请人 |
HITACHI, LTD.;HITACHI VLSI ENGINEERING CORP. |
发明人 |
KAJIMOTO, TAKESHI;SHIMBO, YUTAKA;SATO, KATSUYUKI;OGATA, MASAHIRO;KENMIZAKI, KANEHIDE;KUBONO, SHOUJI;KATO, NOBUO;MANITA, KIICHI;KANAMITSU, MICHITARO |
分类号 |
G01R31/26;G01R31/28;G11C11/401;G11C11/403;G11C11/406;G11C11/407;G11C11/408;G11C11/409;G11C11/4093;G11C29/00;G11C29/02;G11C29/14;G11C29/50;H01L21/82;H01L21/822;H01L21/8242;H01L27/04;H01L27/10;H01L27/108;H03K3/037;H03K19/096;(IPC1-7):G11C7/00 |
主分类号 |
G01R31/26 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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