Non volatile memory device including a predetermined number of sectors
View Patent ↗The device includes a circuit for sector remapping having a CAM (Content Addressable Memory) unit, associated to and in data communication with a multiplexer unit. The CAM unit detects that a sector is defective, it provides the pre-programmed address of a replacing sector and it activates the multiplexer which performs the replacement. The defective sectors and the corresponding locations of the address map are therefore advantageously positioned to the rear to the addressing area. The addressing area is consequently continuous, thus allowing the information to be easily stored and retrieved.
1. A non-volatile memory device comprising:
a memory cell matrix including a plurality of sectors; and
a remapping circuit for remapping defective sectors of the memory cell matrix, defective sectors comprising sectors having at least one defective cell, the remapping circuit comprising a content addressable memory (CAM) unit for detecting defective sectors of the memory cell matrix and including
first memory elements containing defective sector addresses, and
corresponding second memory elements containing replacement sector addresses;
a multiplexer unit connected downstream from and in data communication with said CAM unit, and associated to and in data communication with the memory cell matrix;
said CAM unit activating said multiplexer unit to replace defective sector addresses with replacement sector addresses when defective sectors of the memory cell matrix are detected.
2. A non-volatile memory device according to claim 1 , wherein said CAM unit comprises a non volatile memory.
3. A non-volatile memory device according to claim 1 , wherein said CAM unit comprises a volatile memory which is activated when the memory device is activated.
4. A non-volatile memory device according to claim 1 , wherein the plurality of sectors comprises a higher number of sectors than a nominal capacity of the memory device.
5. A method for restoring a non-volatile memory including a memory cell matrix having memory cells divided into a plurality of sectors, the method comprising:
detecting defective sectors of the memory cell matrix with a content addressable memory (CAM) unit, the defective sectors comprising sectors having at least one defective memory cell;
storing an address of the defective sector in first memory elements of the CAM unit; and
providing a pre-programmed replacement sector address in second memory elements of the CAM unit, the replacement sector address corresponding to a replacement sector to replace the defective sector with the replacement sector among the plurality of sectors of the memory cell matrix;
the CAM unit activating a multiplexer unit in data communication with the memory cell matrix to replace defective sector addresses with replacement sector addresses when defective sectors of the memory cell matrix are detected.
6. A method according to claim 5 , wherein the CAM unit comprises a non volatile memory.
7. A method according to claim 6 , wherein the CAM unit comprises a volatile memory which is activated when the memory device is activated.