SV: Re: [sdiy] DROID3, Another AVR Synth?

[karl dalen]

>> The difference between TI's 100 years and Atmels 10 years is quite
>> vast!

>Yeah, and it's some of the biggest marketing bullshit I've ever seen (I 
>think you refer to the MSP430 datasheets).

As it appears to, and it has puzzled me ever since TI published the
100 year specs, and im puzzled that it seams that very very few are
questioning that spec in public, i have been searching allower the net
and havent found any debate, most folks seams to accept it!
I have asking about this for years on different forums, 
noone really seams to comprehend the issue!  

>Welcome to the world of 
>Arrhenius' law: draw a diagram log10(t) over 1000/T (T in Kelvin!). 
>25°C is then around 3.35, 85°C at 2.79 and 250°C is at 1.91. 100 years 
>with some margin is 10^6 hours. Now we don't know their activation 
>energy but let's say TI tests the Flash at 250°C and it fails after 
>four days at that temperature: 10^2 hours. Draw a straight line between 
>those two points and read the time at 85°C: 6-2=4 decades over 1.44 
>makes 6-4.44=1.56 decades over 0.56 and that is some 30000 hours. 
>Suddenly doesn't look so good anymore, eh? 

Nope!

>Give them the benefit of 
>doubt and say that they'd really make 10^7 hours at RT (which is not 
>too outrageous) and guarantee just 100 years to have some margin and 
>you get just over 11 years retention time at 85°C, which is then 
>equivalent to the Atmel spec (which I didn't read).

>Physics is the same for all Flash memories and refuses to bow to the 
>will of marketing.

Thank's to that, but still it didnt stop TI's management to force it into
their data sheets, strange is that TI's engineers seams to accept
this bull!??
 
> Unfortunately customers still get confused. 

Very, indeed!

>The fact is one could qualify such a memory for 100 of data retention under 
>worst case conditions if you throw enough money and engineering at it. 
>No manufacturer in their right mind will however specify any longer 
>time than what the market pays for as the cost function involved is an 
>exponential. Under typical conditions any modern technology has 
>retention times far longer than the system lifetime.

A pecularity, for example, Ericsson uses/ed the MC68HC11 MCU's 
in every GSM base station for years, and i know that most of these
systems are still in use today, so lets take one station made in
1990 the data retentention is stated  to 10 years over selected temp 
range, don't remember wich, but i have a bounch of these MCU's
and they are still going strong no failures, lets see,  they are on 
their 16'th year of working! 

> Put differently, 
>the failure rate due to retention is an insignificant part of the 
>overall failure rate. If you worry about your MCU working in 20 years, 
>you need to know the FIT rate (failure in time: how many chips fail 
>until 10^9 seconds of lifetime). But then again, unless you have 
>millions of those systems in the field, that number is of no 
>consequence to you for the typical values you can expect.

What if you exceed the maximum number of
writes, shouldent that fuzz up the memory?

Anyhow thanks for the light put on the subject, most informative!

KD