Field-programmable redundancy apparatus for memory arrays
US5153880A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 12, 1990 |
| Grant date | Oct 6, 1992 |
| Priority date | — |
| Expiry date | Mar 12, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C29/838
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A field-programmable redundancy apparatus for integrated circuit semiconductor memory arrays is disclosed. The present invention allows the user to replace a defective memory cell with a redundant memory cell while the integrated circuit memory array is in the field. The user communicates with the redundancy apparatus over the standard signal paths with standard voltage levels of the integrated circuit semiconductor memory array. The redundancy apparatus detects a predetermined code sequence on one or more of the address and data lines of the memory array to enter a special redundancy-reconfiguration mode. In the reconfiguration mode, the redundancy apparatus provides information on the availability and functionality of the redundant memory cells and enables the user to replace a defective memory cell with a selected redundant memory cell. The field-programmable redundance apparatus may comprise nonvolatile memory means, such as EEPROM's, to store the replacements of primary memory cells with redundant memory cells. In the reconfiguration mode, detection of a second predetermined code sequence causes the reconfiguration mode to be exited.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.