Non-volatile memory system card with flash erasable sectors of EEprom cells including a mechanism for substituting defective cells
US5535328A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1995 |
| Grant date | Jul 9, 1996 |
| Priority date | — |
| Expiry date | Feb 23, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/5643
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system of Flash EEprom memory chips with controlling circuits serves as non-volatile memory such as that provided by magnetic disk drives. Improvements include selective multiple sector erase, in which any combinations of Flash sectors may be erased together. Selective sectors among the selected combination may also be de-selected during the erase operation. Another improvement is the ability to remap and replace defective cells with substitute cells. The remapping is performed automatically as soon as a defective cell is detected. When the number of defects in a Flash sector becomes large, the whole sector is remapped. Yet another improvement is the use of a write cache to reduce the number of writes to the Flash EEprom memory, thereby minimizing the stress to the device from undergoing too many write/erase cycling.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.