Will I burn my RPI if I accidentially provide a large voltage to any 3.3v GPIO pin?

[mannok]

Hi there, I am new to electronic side of RPI. I owned a RPI 4B at the moment. And I have several question about RPI GPIO pins.

May I know if I will burn my GPIO in the follow scenarios?

1. Accidentially provide a large voltage to my RPI's 3.3v GPIO pin, e.g. 10v? (I would keep the current at 0.6mA, will it burnt?)
2. Accidentially provide a 3.3v to a GPIO pin which is configured as an output pin. (again, I would keep the current at 0.6mA, will it burnt?)

3. If any of the above question will burn the RPI? May I know how would that be done? In my merely knowledge, because V=IR. Providing any device with a voltage which is large than which is rated will lead to a large current drawn. However, RPI's GPIO won't control/limit its current drawn. Does it mean that it won't burnt as long as I keep the current low at 0.6mA?

Thanks in advance.

[LTolledo]

for #1 try it! and say good bye to your RPi permanently!

and be prepared to be scolded/reprimanded by jamesh, mahjongg, or other RPF staff.

[PeterO]

Hi there, I am new to electronic side of RPI. I owned a RPI 4B at the moment. And I have several question about RPI GPIO pins.

May I know if I will burn my GPIO in the follow scenarios?

The answers are Yes.

PeterO

[boyoh]

Put your Pi backing It’s box before you do any
More damage. Get a breadboard, and learn
Some basic electronics first ,study OHMS LAW
DO NOT USE THE Pi AS THE POWER SUPPLY
on the breadboard, A 0/12dc adapter will
Be very handy. Your understanding of voltage
And current flow is all wrong. Get a book on
Basic Semiconductor Circuits (By Forrest M. Mims.

Regards BoyOh
Retired Electrical / Electronics Technician

[Gavinmc42]

I once connected 12v to a GPIO pin years ago on a old B.
It toasted that pins circuit and the 5V zener protection diode.
But it still seemed to work after I took off the shorted zener.
How much extra damage did to other parts of the circuit I don't know.
It did reboot and run fine except that pin did nothing and missing a zener.

I pretty much learnt most of my electronics by reading Forest Mims handbooks

[mahjongg]

In short:

RPI GPIO inputs are NOT 5V tolerant!


Longer version:
They are not even more than 3.9 to 4.0V tolerant, in fact any voltage greater than 0.6 to 0.7V (a diode forward drop) more than the GPIO supply voltage (3.3Volt) , that is 3.3+0.7=4.0V, can cause a "latchup", and the current that causes the trigger can be tiny, so current limit resistors won't help.

Technical background:
Latchup is the inadvertent creation of a low-impedance path between the power supply rails (VCC and GND) of a MOSFET circuit, caused by triggering a parasitic n-p-n-p SCR (Thyristor) structure, leading to its destruction due to overcurrent from VCC (3.3V) to GND inside the chip.
see: https://en.wikipedia.org/wiki/Latch-up

[boyoh]

Hi there, I am new to electronic side of RPI. I owned a RPI 4B at the moment. And I have several question about RPI GPIO pins.

May I know if I will burn my GPIO in the follow scenarios?

1. Accidentially provide a large voltage to my RPI's 3.3v GPIO pin, e.g. 10v? (I would keep the current at 0.6mA, will it burnt?)
2. Accidentially provide a 3.3v to a GPIO pin which is configured as an output pin. (again, I would keep the current at 0.6mA, will it burnt?)

3. If any of the above question will burn the RPI? May I know how would that be done? In my merely knowledge, because V=IR. Providing any device with a voltage which is large than which is rated will lead to a large current drawn. However, RPI's GPIO won't control/limit its current drawn. Does it mean that it won't burnt as long as I keep the current low at 0.6mA?

Thanks in advance.

I think you are looking at Ohms Law in reverse
All Inputs & Outputs have Impedance (Resistance)
This means how much current they will Source or Sink when operating at their designed values
Going over their designed values will cause them to
Fail ( burn out) So keep the Voltage and Current
Whiten their designed values.

Regards BoyOh

[rpdom]

As others have already said, the answer to 1. is Yes, connecting more than around 4V (or below -0.7V) on any GPIO pin will damage the GPIOs and will probably lead to fatal system damage (maybe not straight away, but parts of the chip will keep burning out over time).

For 2. The answer is that it could damage the GPIO unless you put a current limiting resistor in line with the GPIO output. 1K is sufficient to limit the current to a safe level for the Pi.

For 3. it is the voltage that matters, not the current. The GPIO inputs are like FETs - they are voltage driven, not current. The actual current needed to drive a GPIO input is in the microAmp range.

[emma1997]

the current that causes the trigger can be tiny, so current limit resistors won't help.

it is the voltage that matters, not the current. The GPIO inputs are like FETs - they are voltage driven, not current.

It's surprising even top experts are not 100% aligned. My understanding is there can be no current w/o voltage and versa vice. Ohms law and junction chemistry both play a part. From a previous post: https://www.raspberrypi.org/forums/view ... 7#p1577337

Working in the semi industry indicated to me at that time just applying a voltage (or current) did not latch. Applying voltage to a pin above avalanche threshold to unpowered IC then vcc after that was what killed chips back then. At least the line I was responsible for. IDK if semiconductor physics are that different for more modern processes. I suspect not much.

Somewhat more recently (about the time joined here) I was actually hired to test a handful of PI2 to destruction. Input abuse was among the torture techniques. My results did not coincide exactly with many of the belief systems floating around here. It was impressive how rugged the Pi turned out to be.

No matter what IMO best stick with the company line and keep at or below 3.3v. If nothing more a matter of liability than anything else (don't come crying if you fail to listen to james, mahjongg, and other top engineers and fall down go boom, lol).

Virtually all modern sensors and MCU (PIC, AVR, STM) run at 3.3v so rarely any need to violate the Pi spec which is clear.

[davidcoton]

My understanding is there can be no current w/o voltage and versa vice.

There can be current without voltage, but only with zero resistance.
There can be voltage without current, but only at infinite resistance.

The above is only strictly valid for DC conditions. For AC (or alternating voltage), replace "resistance" with "impedance", and modify your definition of zero and infinite to make the equations work with complex numbers.

[emma1997]

True. I was referring to an actual electrical "circuit" which does seem to need a bit of each. No such thing as perfect short or open on this planet.

My measurements showed inputs somewhere above 10Gohm but less than 100Gohm the limit of my gear. That might be moisture between pins or other epoxy adulterant for the DUT. So for MOS devices we probably all agree capacitance not resistance is certainly the big deal.

[davidcoton]

No such thing as perfect short or open on this planet.

Superconductivity?

[emma1997]

Well I'm not so experienced in that realm but my understanding is there are issues associated with negative resistance and similar phenomena which do not equate to exactly 0. AFAIK kinda flutters around or pass through that point. So I would have to say you are correct in the same way as a dead clock is exactly correct at least once a day. lol

To drift slightly back on topic this probably does not refer to PI input which is unlikely to have infinitely high resistance. However for practical purposes we can ignore any I think.

[W. H. Heydt]

The above is only strictly valid for DC conditions. For AC (or alternating voltage), replace "resistance" with "impedance", and modify your definition of zero and infinite to make the equations work with complex numbers.

And bear in mind that for EE purposes, the square root of -1 is j.

[LTolledo]

...... just waiting for the OP to re-appear and check out his post on the result of his "wild experiment" with the RPi GPIO

am sure most of us will be "entertained"

[mannok]

...... just waiting for the OP to re-appear and check out his post on the result of his "wild experiment" with the RPi GPIO

am sure most of us will be "entertained"

haha, I keep monitoring the post indeed. Thank you for all the answers.