Re: Flash retention in uC at higher temps, experience?

"Jim Granville" <no.spam@[EMAIL PROTECTED]
> wrote in message
news:48548d1f$1@[EMAIL PROTECTED]
> TheM wrote:
>> It could be a design with long supply wires (as antennas) and poor RF
>> blocking caps close to uCPU.
>>
>> Flash corruption due to EM field at 6 feet distance sounds a bit far
fetched.
>
> It will not be a Direct Flash Cell effect, but more likely a Software
> crash, that jumps into a Flash Write routine.

Yep, I thought that was the real cause. I think Joerg pointed out GSM
phones
can be especially nasty with their pulsed carrier.

100W VHF at 6-feet away should be relatively easy to counter with proper
pcb
layout and ferrite beads and RF blocking caps, but designer probably never
expected
strong rf fields. Even worse would be if the write protection fuses were
not set.

> This is one reason why many Automotive designs insist on a FLASH_ENABLE
pin, so that a simple SW crash CANNOT cause un-recoverable 
> damage.

I suspect the programmed fuses that should prevent writing over flash
section may
not always work. External pin is probably more reliable.

M