Zone boundary adjustment for defects in non-volatile memories
First Claim
1. In a non-volatile memory system comprising a memory having a plurality of physical blocks of non-volatile storage elements, wherein the storage elements within individual ones of the blocks are simultaneously erasable, and a memory controller circuit that controls programming of data into addressed blocks, reading data from addressed blocks and erasing data from one or more addressed blocks at a time, wherein for address translation the controller organizes the non-volatile storage elements into logical subdivisions of the physical memory each comprised of one or more blocks, a method comprising:
- providing test criteria, including a minimum number of non-defective blocks for each of said logical subdivisions;
testing said memory blocks to determine defective ones of the memory blocks; and
assigning a correspondence of blocks to zones based on the results of said testing so that said test criteria are met.
2 Assignments
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Accused Products
Abstract
A non-volatile memory is divided into logical zones by the card controller in order reduce the size of the data structures it uses for address translation. Zone boundaries are adjusted to accommodate defects allowed by memory test to improve card yields and to adjust boundaries in the field to extend the usable lifetime of the card. Firmware scans for the presence of defective blocks on the card. Once the locations of these blocks are known, the firmware calculates the zone boundaries in such a way that good blocks are equally distributed among the zones. Since the number of good blocks meets the card test criteria by the memory test criteria, defects will reduce card yield fallout. The controller can perform dynamic boundary adjustments. When defects occur, the controller can perform the analysis again and, if needed, redistributes the zone boundaries, moving any user data.
35 Citations
12 Claims
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1. In a non-volatile memory system comprising a memory having a plurality of physical blocks of non-volatile storage elements, wherein the storage elements within individual ones of the blocks are simultaneously erasable, and a memory controller circuit that controls programming of data into addressed blocks, reading data from addressed blocks and erasing data from one or more addressed blocks at a time, wherein for address translation the controller organizes the non-volatile storage elements into logical subdivisions of the physical memory each comprised of one or more blocks, a method comprising:
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providing test criteria, including a minimum number of non-defective blocks for each of said logical subdivisions; testing said memory blocks to determine defective ones of the memory blocks; and assigning a correspondence of blocks to zones based on the results of said testing so that said test criteria are met. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification