Semiconductor memory device facilitated with plural self-refresh modes
US5467315A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Apr 28, 1994 |
| Grant date | Nov 14, 1995 |
| Priority date | — |
| Expiry date | Apr 28, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2029/5004
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
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 devi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.