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Scrub techniques for use with dynamic read

  • US 8,687,421 B2
  • Filed: 03/30/2012
  • Issued: 04/01/2014
  • Est. Priority Date: 11/21/2011
  • Status: Active Grant
First Claim
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1. A method of operating a non-volatile memory system, the memory system including a controller circuit and one or more non-volatile memory circuits having a plurality of physical units of one or more blocks, the method comprising:

  • maintaining a set of read parameters for use in reading operations of memory cells of the memory circuits, the set of read parameters including read parameters for a default read case and read parameters for a plurality of distinct, shifted read cases;

    for each of the physical units, maintaining a correspondence between the physical unit and a which of the read cases to use when reading the physical unit;

    performing a read operation for a page of data using the corresponding read case for the physical unit to which page belongs;

    determining whether the read operation was successful or yielded a fail result;

    in response to a read operation yielding a fail result, selecting a shifted read case at which the page can be read; and

    based on the shifted read case selected, determining whether to refresh the block to which the page belongs.

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