NOR flash wear - what exactly happens when writing to a sector that have been ersaed too much

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Anonymous
Not applicable

I am trying to understand what will happen to a NOR flash after a single sector is erased to the maximum capacity:

1.- How do you expect this sector will behave (in terms of malfunctioning) when writing and reading?

2.- Will this defective sector have any influence in the other sectors that have not been used?

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1 Solution
VincentH_06
Employee
Employee
10 replies posted 5 replies posted First solution authored

Hi Daniel,

Due to the physical characteristic, all the NOR flash have life time with the limit program/erase cycles, which called endurance. Endurance is related with the program/erase cycles and temperature. With the higher program/erase cycles, the data retention (time of the cells can hold the data) will be worse than before, if your program/erase operations with very short interval and many times on one specific sector, it will accelerate the aging speed of this sector.

For your questions, please see the comments as follow:

1.- How do you expect this sector will behave (in terms of malfunctioning) when writing and reading?

--------The data read/written will be abnormal with incorrect value, and the time for the cell to retain the programmed data will be extremely shorter than the normal sectors  

2.- Will this defective sector have any influence in the other sectors that have not been used?

--------The endurance and data retention is the "sector based" conception, the defect sector will not effect other/neighbor sectors from the physical perspective.

For more information, please refer our KBAs and AN from the following links:

Rapid Cycling and Data Retention – KBA220414

How long will data be retained in Cypress Flash memory devices if only a few erase cycles are planne...

http://www.cypress.com/documentation/application-notes/an217979-endurance-and-data-retention-charact...

Thank you!

Vincent Han

Customer Application Engineer, Cypress

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1 Reply
VincentH_06
Employee
Employee
10 replies posted 5 replies posted First solution authored

Hi Daniel,

Due to the physical characteristic, all the NOR flash have life time with the limit program/erase cycles, which called endurance. Endurance is related with the program/erase cycles and temperature. With the higher program/erase cycles, the data retention (time of the cells can hold the data) will be worse than before, if your program/erase operations with very short interval and many times on one specific sector, it will accelerate the aging speed of this sector.

For your questions, please see the comments as follow:

1.- How do you expect this sector will behave (in terms of malfunctioning) when writing and reading?

--------The data read/written will be abnormal with incorrect value, and the time for the cell to retain the programmed data will be extremely shorter than the normal sectors  

2.- Will this defective sector have any influence in the other sectors that have not been used?

--------The endurance and data retention is the "sector based" conception, the defect sector will not effect other/neighbor sectors from the physical perspective.

For more information, please refer our KBAs and AN from the following links:

Rapid Cycling and Data Retention – KBA220414

How long will data be retained in Cypress Flash memory devices if only a few erase cycles are planne...

http://www.cypress.com/documentation/application-notes/an217979-endurance-and-data-retention-charact...

Thank you!

Vincent Han

Customer Application Engineer, Cypress

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