Non-volatile storage device, non-volatile storage system, and memory control method with a refresh processing of a data

Patent metadata

Field	Value
Publication number	US-9965202-B2
Application number	US-201615079959-A
Country	US
Kind code	B2
Filing date	Mar 24, 2016
Priority date	Mar 26, 2015
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A non-volatile storage device of the present disclosure includes non-volatile memory configured to have a plurality of areas for storing data, and a memory controller configured to write the data to the non-volatile memory and to read the data from the non-volatile memory. The memory controller includes a memory interface (I/F) connected to the non-volatile memory, a threshold calculator calculating a threshold for the number of error bits of the data based on a storage condition in the case of storing the data in the non-volatile memory without power, and a refresh controller determining whether refresh processing of the data is necessary, based on the threshold and the number of error bits of the data, and executing the refresh processing of the data if the refresh processing of the data is necessary.

First claim

What is claimed is:

1. A non-volatile storage device comprising:
a non-volatile memory configured to have a plurality of areas for storing data; and
a memory controller configured to write the data to the non-volatile memory and to read the data from the non-volatile memory, the memory controller comprising:
a memory interface (I/F) connected to the non-volatile memory;
a threshold calculator for calculating a threshold for the number of error bits of the data based on an expected period for which the non-volatile memory is stored without power; and
a refresh controller for determining whether refresh processing of the data is necessary, based on the threshold and the number of error bits of the data, and executing the refresh processing of the data if the refresh processing of the data is necessary.

2. The non-volatile storage device according to claim 1 , wherein the threshold calculator calculates the threshold for each area of the plurality of areas of the non-volatile memory.

3. The non-volatile storage device according to claim 1 , wherein the expected period for which the non-volatile memory is stored without power is set by a user.

4. The non-volatile storage device according to claim 2 , wherein:
the non-volatile memory stores a number of rewriting operation times on each area of the plurality of areas, and
the threshold calculator calculates the threshold based on the number of times of rewriting.

5. A non-volatile storage system comprising:
an access apparatus; and
a non-volatile storage device connected to the access apparatus, the non-volatile storage device including:
a non-volatile memory having a plurality of areas for storing data; and
a memory controller writing to the data to the non-volatile memory and reading the data from the non-volatile memory, wherein:

the access apparatus calculates a threshold for the number of error bits of the data based on an expected period for which the non-volatile memory is stored without power, and transmits the threshold to the non-volatile storage device, and
the memory controller includes a refresh controller determining whether refresh processing of the data is necessary based on the threshold and the number of error bits of the data, and executing the refresh processing of the data if the refresh processing of the data is necessary.

6. The non-volatile storage system according to claim 5 , wherein the access apparatus calculates the threshold for each area of the plurality of areas of the non-volatile memory.

7. The non-volatile storage system according to claim 5 , wherein the expected period for which the non-volatile memory is stored without power is set by a user.

8. A memory control method for non-volatile memory in which data is stored, the method comprising:
calculating a threshold for the number of error bits of the data based on an expected period for which the non-volatile memory is stored without power;
determining whether refresh processing is necessary based on the threshold and the number of error bits of the data; and
executing the refresh processing of the data if the refresh processing of the data is necessary.

9. The memory control method according to claim 8 , wherein the expected period for which the non-volatile memory is stored without power is set by a user.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Kogita Shigekazu
• So Hirokazu
• Honda Toshiyuki

Classifications

• G06F3/0619 Primary

  in relation to data integrity, e.g. data losses, bit errors · CPC title

• G06F3/0653

  Monitoring storage devices or systems · CPC title

• G11C16/10

  Programming or data input circuits · CPC title

• G11C16/3431 Primary

  Circuits or methods to detect disturbed nonvolatile memory cells, e.g. which still read as programmed but with threshold less than the program verify threshold or read as erased but with threshold greater than the erase verify threshold, and to reverse the disturbance via a refreshing programming or erasing step · CPC title

• G11C16/26

  Sensing or reading circuits; Data output circuits · CPC title