Re: M25P32 failure

In article <IK->, Vladimir Vassilevsky <> wrote:
>
> We are using M25P32 flash memory in one of the projects. It is used as
>a boot memory; normally, it is written only once or twice. However,
>there is a significant percent of failures; almost 25% of parts quit
>working after several weeks of operation. The failure is gradual: it
>starts like occasional hangups while reading or programming, then it
>happens more and more often, and at last the part fails entirely.
>What could it be? Have you encountered anything like that?

We have a few products that use these, several thousand units in the field for
a few years now and not a single problem; at least not with the M25P32

Our usage pattern is a bit different though, they get continuous reads for 1-8
hours per day and then a sector erase & write maybe once a month or so.
Although there is one product where they do get 2-3 bytes written once per
second and that's been OK too. They're running at 3.3V and I believe the clock
rates on the SPI are between 0.8 and 4.0 MHz depending on the product.

What exactly do you mean by hangups? Do you mean that the WIP bit in the
status register remains set for longer than it should during a write / erase?
The maximum times for write, sector erase, and bulk erase are 5 ms, 3000 ms
and 80000 ms respectively (yes, the bulk erase feature is a bit of a joke). I
don't see how you could have hangups during reading, since there's really
nothing to wait for during a read so either you get the correct data or you
don't.