xc9536xl IO over voltage

[maxim]

Should be that an over voltage on an IO pin damage flash data witjhout damaging chip macro cells?

[drjohnsmith]

If you IO over voltage, any thing can happen,

What error do you see ?

Typicaly the IO can look like its still working, because of the parallel output transistors,

Outputs can be thought of as being made of many parallel transistors , small low current ones but fast for initial drive, through to BIG slow ones for current .

Small blow much easier than the big ones, giving impression IO is still working,

[maxim]

The IO that dosn't work, is inverted regard to normal configuration, is not the output that can get the over voltage.

The device is sealed with resin and the only pins thet can be connected outside is the input coding address that seem to work.

The input coding usually is setted with jumper.

I have seen that canging little bit the power supply from 3 volt to 3,3  the device stop totaly to working, but the supply current seem to be normal.

[maxim]

I'm looking for technological question and the configuration forum isn't, I think, the right one.
I made hundreds of my devices that works without problem, but just one that was working fine after 6 months have been to stop to work ready.
the component that doesn't work ready any more is a xc9536xl plcc44.

All others components on devices still works fine
I think that the customer have damaged the device with external action like over voltage o laser.
The device is sealed with resin, except for some input pins, and is a very big problem try to reconfigure xc9536xl.
I have seen that if the power supply of the device is low like 2,9 volt seem to almost work except for an output that is inverted respect the normal configuration and if I put the power supply to 3,3 volt the xc9536xl stop to work completely.

[u4223374]

Not working at 3.3V is very odd, since that's right in the middle of the recommended voltage range (3.0 - 3.6V). I can't imagine any damage to the device that would leave it working at 3.0V but not at 3.3V.

It's not just something silly like the chip overheating, is it? The 3.0V vs 3.3V thing could potentially cause that, and I've seen heat dissipation issues with potted devices in the past.

[maxim]

There isn't any over heating or abnormal current absorption .

The current is 30/40 mA both at 2,9/3v that 3,3v . Like all the others chips that works fine.

The customer, I think, did something of very strange like abnormal laboratory test or just caused the problem to try to recover information to reverse engineering my device .

I don't know and I'm tryng to define the exact cause of device disfunction to final reply to customer, to clode definitively the procedure.

It's very hard I know but I need to make a reply to him becouse he is trying to be clever with me.