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Giving Jaguar the Acid Test 
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Good suggestion, however how can this be done at home in a reliable repeatable way?

And why would a CPU in a fully populated circuit be susceptible when the CPU itself is not? (to its own spec)

There is also load-dump testing, however it's not designed to handle that, so testing for it is kinda stupid.

Fred.

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Fri Aug 30, 2013 10:54 pm
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It is more for handling and installing. I guess you can ignore it since its low volume. Test it by hitting all external I/Os with a cigarette lighter spark against other I/Os, ground, etc. Relatively easy test. Then, you can call it indestructible. :D Sort of...


Fri Aug 30, 2013 11:07 pm
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I meant handling and installing too. Fully populated = built not while being built. The CPU is inert to this to a certain level (as specified in the data sheet), it's going to be better, not worse, surrounded by application circuit from all sides.

Good idea re bbq ignition circuit, or similar. How about a relay turn off spike? We need something measurable and compliant with some relevant specification, or it's not a lot of use "yeah, the voltage was high" - "how high" - "don't know".

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Fri Aug 30, 2013 11:26 pm
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There isn't anything you can do during board assembly except to trust the spec of the parts and take extra precautions. I have access to an ESD Generator at work. Spark plug is another way and you can find specs for those.


Fri Aug 30, 2013 11:54 pm
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I have no idea how that post was relevant. I won't hold it against you, though.

We're talking about testing the fully populated board, where the CPU is isolated by numerous capacitors and resistors and diodes and extremely unlikely to be hurt by synthetic clothing.

Before built, who cares, if the builder is an idiot, that's their problem :-)

Fred.

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Sat Aug 31, 2013 12:42 am
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I misunderstood what you said on the non-populated board.

Obviously, the test is only for fully populated board. You said you wanted indestructible. It won't be if it can't even pass a simple ESD test. I read the schematic, I know it is unlikely. Otherwise, I would have suggested ESD devices to the design. The point is to actually test it right?


Sat Aug 31, 2013 1:03 am
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Yeah, it is. Typical failure modes are these:

User wires wrong pin to wrong thing, power out receives ground or ground out receives power or input receives power, or 5v out receives more than 5v.

and

Bad/careless wire routing leads to wires chaffing through and achieving the same end result as above.

It's pretty uncommon for a synthetic pink tshirt to end up floating around in the engine bay attracting bare wires ;-)

Fred.

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Sat Aug 31, 2013 1:08 am
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You just don't give up do you :D It was just a simple suggestion that was easy to perform, and adds another positive spec on paper. Try not to get too caught up on it. I already said the odds were low. I am only pulling your leg because you said indestructible. :-)

And its not just for the CPU. Its also for FETs, the FT232, etc. It is not uncommon to put addition ESD protection on top of already protected devices.

I'll just keep out of your way from now on. It seems I am bringing you more frustration. :D I'll just be another user.


Sat Aug 31, 2013 1:26 am
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I know it is, and we more or less have that. All ADC inputs have caps on their pins and current limit resistors with diodes to rails. In the time it took the diode to switch, the cap could not have significantly charged. I could be wrong about this, and I know the HV nature of it makes a difference, however there is almost no point if we can't quantify what exactly we tested. IE, we need a voltage, duration, current, energy level, set of params for any meaningful ESD style testing.

FT232 goes through an isolator which handles plenty of volts. It's fine to fry a non-running part of the comms gear, this doesn't have to be robust at all.

FETs are vclamped and ESD protected too. FET drivers may be vulnerable to it, but again, without some sort of test spec it's almost completely pointless.

No, you can't be a user, we don't have any users at all. Only helpful testers who add value and aren't burdens. Staying out of the way is a counterproductive thing to do. However intentionally wasting my very limited time by "pulling my leg" about indestructibility is fucking brain-dead. Cease and desist from such behaviour, please...

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n00bs, do NOT PM or email tech questions! Use the forum!
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Sat Aug 31, 2013 2:36 am
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I suggested a test that you didn't plan to include. I did all I was allowed to do before receiving the burden and useless award. I'd be glad to help. But it seem we have a big issue with communication and understanding. You already rejected the idea instead of putting it at the bottom of the queue. You have issues man. lol... Lighten up.


Sat Aug 31, 2013 3:14 am
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