Go Down

Topic: Why arduino can fry? (Read 2 times) previous topic - next topic

dhenry

Quote
I've accidentally shorted outputs and even inserted the 328P backwards


You are in good company there, :).

People screaming about "damages" here simply have no idea what they are talking about; or don't understand the datasheet when they quoted it as support.

Some OEMs went so far to specify shortcircuit current.

Groove

Quote
People screaming about "damages" here simply have no idea what they are talking about; or don't understand the datasheet when they quoted it as support.

Hey! Look people - we've got our very own troll.
Per Arduino ad Astra

James C4S


FWIW... I've accidentally shorted outputs and even inserted the 328P backwards... never hurt the chip (yet).

Damaged components don't always fail immediately after being damaged.



People screaming about "damages" here simply have no idea what they are talking about; or don't understand the datasheet when they quoted it as support.

I'm bookmarking this as a great example of "the pot calling the kettle black."
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

MarkT



Quote
Low (dc) resistance isn't the issue: you can actually short your avr's pins without damaging them

You've done this?


FWIW... I've accidentally shorted outputs and even inserted the 328P backwards... never hurt the chip (yet).

I don't think you can claim that - appearing to still work is not the same as undamaged - overloading the output transistors causes local overheating and perhaps electromigration on the chip which will first degrade then disable the transistors in that area - the reliability and robustness is impaired before obvious/gross loss of function is seen.  Once degraded the risk of future failure without warning is increased.  Manufacturers put values in the abs max spec that are just conservative enough (they don't want to be sued for being unfit-for-purpose, yet want to look as good as possible compared to the competition...  I would always recommend staying below them by a sensible margin.

Quote

Of course, in reality the datasheet specs MUST be adhered to or else the chip WILL get ruined sooner or later.


A more positive spin is obey the abs max constraints so you end up with about strange unexplaned failures in the future!


You
[ I won't respond to messages, use the forum please ]

Docedison

Most (in my experience) "newer" Microprocessors will withstand an accidental short once or twice... to ground, even occasionally instead of once or twice. Most All Microprocessors will survive a short to Vcc once or twice but likely never occasionally and No microprocessor will survive shorting to a positive supply greater than Vcc to less than ground (Negative voltages) without a resistor big enough to limit the current to what the input protection diodes can withstand. Some types of micro's are more robust than others and for some obvious reasons the choice of the Atmel product was a wise one. The '328's are a hardy chip family. I've never yet read here that shorting an "output" pin to ground will destroy that pin or the processor instantly or even soon. I've read many times of the per pin current limits and infrequently of "other" types of shorts. I've NO DOUBT  that a long term short... 5 - 10 minutes would cause enough internal heating to begin the "electromigration" mentioned and even cause the device to fail. That's one major issue with mos devices and overheating from wrong type loads is the major failure event for Mosfet power transistors (Bipolar devices fail in a similar manner from "second breakdown" which is a place on the "overloaded" transistor die that has a crystalline defect, the defect gets hot and fails causing more area's near the failure to fail until the device fails utterly. If the same transistor is never operated at or above it's rated max current these types of failures are most rare. I used to test silicon power transistors for that issue by measuring the C-E resistance... it should be a near open circuit > 5 megs. Measurements less than 50K were a danger flag for me and I replaced those parts. With a mosfet there is no easy way to look for electromigration unless it be in the gate capacitance... The defect in my experience is mainly damage to the gate structure (The oxide layer under the gate metallization) and the damage is really unnoticeable until the device fails although my high power fet use was limited to RF power amplifiers. I used many power mosfets but the ones that failed were the ones that regularly were operated at 100 + Deg C (failed fans or air filters clogged). All of the above mentioned conditions are "Over the Top" and are the exception rather than the rule.... There have been a lot of "My Pin puts out 1.5V... Why? types of questions but not many in which the poster reported failure because of the error...
Did I "Fry" my Uno?, I accidentally connected a pin to Vcc or ground or I connected my servo power to a pin on the Uno because I wanted to turn off the motor...
but rarely reports that the device utterly failed. Common sense is the key here, A short should be avoided if at all possible but isn't cause for failure or ALL of us would be seeing more messages to that effect. Great topic for "Trolling" though... I suspect someone got stood up for "Saturday Night" and is revealing his/her frustration here...

Bob
--> WA7EMS <--
"The solution of every problem is another problem." -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Go Up