Lpc2000

Hi Dave,

let me try to explain. The 10 years are specified after all 10k 
reprogramming cycles done. It is all about how many ppm (or for that 
matter fits) the device will have. The target is always to have 0 
failures over the specified time. Statistically thats not really 
possible but every vendor tries the best to get as close as possible. 
With this is mind the typical retention is much more along the value of 
100 years (no typo) than 10 years. Typical being that even at 100 years 
less than 1 in 100 may be less than 1 in 1000 devices is expected to 
fail.

So, in an attempt to answer your question what happens after ten years? 
The probability of one bit in the whole flash memory failing increases 
day by day, and after ten years the fit rate is just a little higher 
than after 1 year and just a little lower than after 20 or even 50 or 
100 years. To the closest approach what will happen, nothing bad to the 
flash.

There was an answer from Robert stating that reprogramming cycles have 
a stronger effect on the data retention than temperature, well both 
have an effect because high temperature is used to simulate fast aging, 
so at higher temperatures, the years go by faster ;-) 

Given your less than 60C and just a few programming cycles, though 
shall not fear any failures in more than 20 years. 

Hope this help, Robert


--- In lpc2000@yahoogroups.com, "foreigner_ca" <va3dp@r...> wrote:
> Hello to all, this is my first post in this group.
> 
> I'm thinking of using the LPC2138 in a design that must have a 20
> year life cycle. The literature says the flash has only 10 year 
> retention, but in other flash devices that is affected by
> temperature, write cycles etc. 
> 
> Is there any more detailed info on this? For example, if I only write 
> to the flash a few times and keep the temperature below 60C, can I 
> expect longer retention?
> 
> Cheers
> Dave