Device and method for resolving an LM flag issue

摘要

The reliability with which data can be read from a storage medium, such as flash memory storage medium, is enhanced by updating an upper limit of a reading threshold voltage window for a respective portion of the storage medium. For each memory cell in the respective portion of the storage medium, a memory controller is configured to perform a plurality of sensing operations and obtain results from the plurality of sensing operations, where the plurality of sensing operations includes sensing operations using a predefined range of offsets from a previously established reading threshold voltage. The memory controller is further configured to determine the updated upper limit of the reading threshold voltage window based on the-results from the plurality of sensing operations, and store the updated upper limit of the reading threshold voltage window for the respective portion of the storage medium.

主权项

1. A method performed by a memory controller of updating an upper limit of a reading threshold voltage window for a respective portion of a storage medium, the method comprising:
during read patrol operations, adjusting one or more reading threshold voltages associated with the respective portion of the storage medium; after adjusting the one or more reading threshold voltages, detecting a predefined lower-middle (LM) flag issue; and in response to detecting the LM flag issue, performing a sequence of operations comprising: for each memory cell of a plurality of memory cells in the respective portion of the storage medium:
performing a plurality of sensing operations, wherein the plurality of sensing operations includes sensing operations using a predefined range of offsets from a previously established reading threshold voltage; andobtaining results from the plurality of sensing operations; determining an updated upper limit of the reading threshold voltage window based on the results from the plurality of sensing operations performed on the plurality of memory cells in the respective portion of the storage medium; and storing the updated upper limit of the reading threshold voltage window for the respective portion of the storage medium.