[En-Nut-Discussion] confiability of Flash memory

[Harald Kipp]

Hi,

I've not much experience with AT49 chips, but several years
of experience with Atmel's flash memory build into the AVRs.
The early ATmega103 guaranteed 1000 cycles only and I had
just one chip with a wear-out flash. Two or three had been
reported by customers. 1000 erase cycles can be reached easily
during development, as the AVRs cannot run software in RAM
like the ARM7 on Ethernut 3.

I've heard from other people who did tests and had to
do twice the number of erasures until the first bits
needed more than one erase cycle to switch back to 1.

Thus I'd say, that you can be really optimistic, that the
chip will survive the number of guaranteed cycles. However,
it is possible, that a very low number of chips may be less
reliable than 99.9% of them and may fail earlier.

We recently had a no-name SD card tested on Ethernut 3, which
failed after a few hundred file create/delete cycles.

Harald

At 10:15 20.03.2006 +0100, you wrote:
>Hi all:
>
>I'm working with the Flash memory integrated in my Ethernut 3 to store
>data, and I need to know how confiable is the minimum number of 100,000
>erase cycles that Atmel gives for its AT49BV322A.