What is the write limit for DataFlash products such as AT45DB641E?

Can multiple writes to the same byte be performed without erase? Of course individual bits can only be set from 1 to 0. Unchanged bytes would be written as FFh in the buffer.

I think documentation from the 8Mbit part several years back did specify this. The current documentation doesn't 'specify' any endurance parameters except in the informative highlights section on page 1. This is quite unusual for a flash memory datasheet.

Thanks, Ross

  • With NOR flash, you can change 1 bit to 0 using a rewrite (as you mentioned) but not the other way around.
    For this reason to return bits to 1 you must use erase operation first.
    Main Memory Byte/Page Program will allow bytes to be programmed into "previously erased locations" only in the main memory array.
    In regards to the endurance parameter:
    For AT45DB641E 100,000 program/erase cycles per page minimum and Data retention: 20 years.

    Best regards,
    Renesas Electronics Online Support

  • Thanks Sarpa.

    I have seen some (not common though) flash devices which specifically advise against writing to a cell more than once between erases (or sometimes at most twice). Good to hear AT45DB641E isn't one of those.

    Cheers, Ross

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