[sdiy] EPROM/flash lifetime

[ASSI]

On Donnerstag, 9. Februar 2006 19:31, Barry Klein wrote:
> 1) For EPROM's and Flash - is the lifetime a shelf lifetime or data
> lifetime?

Depends on the specification. If it is not explicitly given, you have to 
assume total lifetime to stay on the safe side. For retention of EPROM 
or Flash it does not matter if the part gets a supply or not (assuming 
it doesn't self-heat).

> 2)If you take a 10 year old eprom and re-write it is it good for
> another 10 years or must it be replaced with a NEW part?

For the EPROM cells themself: yes, if erased and programmed properly. 
For the whole chip, package and system: depends, but at least if it is 
in-system programmable, things should be fine. If you are in doubt, 
replace with a new part, quality control has quite a bit improved from 
20 years ago.

> 3)Has anyone done a study on just what the lifetime is on common ~20
> year eproms has been?  Should we count on our older synths failing
> for this problem (or my ham radio, or my scope, or....)

If you mean those with quartz windows, some people have had 
problems with them after 20 years, not always the fault of the EPROM. 
Some early failures that I've witnessed (after a much shorter time) were 
the fault of the programmer. The same EPROMs re-programmed with the 
correct algorithm still work fine. 

> 4)Are EPROMs even being made now with ROHS forcing new processes?

New packages only, the chips and their manufacturing process are the 
same.


Achim.
-- 
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