Device based wear leveling using intrinsic endurance
AssigneeSanDisk Technologies LLC
InventorsJonathan Wolfman, Dana Lee, Jonathan Hsu
Life of this patent
Estimating the term…
Abstract
A system for improving the management and usage of blocks based on intrinsic endurance may be used to improve memory usage for flash memory, such as a memory card. The overall card endurance may be extended by cycling blocks with higher intrinsic endurance over the lowest endurance target of the worst block. This may be accomplished by managing blocks with different intrinsic endurance values internally or by partitioning the blocks with different intrinsic endurance values externally for different usage.
Claims20
A flash memory device comprising:
- a non-volatile storage having an array of memory blocks;
- and
- a controller in communication with the non-volatile storage, wherein the controller is configured to:
- estimate an intrinsic endurance based on physical characteristics during usage for the memory blocks individually;
- assigning bins for the memory blocks based on the intrinsic endurance, wherein the bins reflect relative endurance of the memory blocks;
- and
- adjust usage patterns of the memory blocks based on the assigned bin for each of the memory blocks, wherein the adjustment of usage patterns comprises managing wear leveling based on the assigned bins and comprises adjusting trim parameters based on the assigned bins.
A method for block level grading in flash memory comprising:
- in a non-volatile storage device having a controller and blocks of memory, the controller is configured for:
- measuring a cell voltage distribution;
- estimating an intrinsic endurance of individual blocks of memory based on the cell voltage distribution during usage of the non-volatile storage device, wherein the cell voltage distribution comprises a physical characteristic that reflects the intrinsic endurance of the individual block;
- assigning bins for each of the blocks of memory based on the intrinsic endurance reflected by the cell voltage distribution, wherein the bins correspond with values of the cell voltage distribution;
- and
- adjusting programming of the non-volatile storage device based on the assigned bin, wherein the programming that is adjusted comprises using a lower voltage for the memory blocks in one or more of the bins that correspond with a lower value of the intrinsic endurance and comprises using a higher voltage for the memory blocks in one or more of the bins that correspond with a higher value of the intrinsic endurance.
A method for operating a memory system that includes an array of memory blocks and a controller in communication with the memory blocks, the method comprising:
- determining a cell voltage distribution or a count of failed bits for the block;
- predicting an intrinsic endurance for the blocks based on the determined cell voltage distribution or based on the count of failed bits;
- providing the predicted intrinsic endurance to a host;
- partitioning, by the host, the blocks based on the intrinsic endurance;
- and
- receiving, from the host, assignments of data based on the partitioning from the intrinsic endurance provided, wherein blocks with a higher intrinsic endurance are assigned data that requires higher data retention and blocks with a lower intrinsic endurance are assigned data that requires less data retention, wherein the blocks are partitioned by the host.
Dependencies are inferred from the claim text.