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Does the RPi 4 have any kind of protection against reverse voltage when the GPIO header is used?

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    You commented on Joan's answer. If you are contemplating using a series diode this is an unreliable method. You should use a diode clamp to supply rails - which is the normal protection mechanism.
    – Milliways
    Mar 14, 2023 at 21:43
  • Thank you Milli for pointing to that. Indeed that was I wanted to to, soldering it anti-parallel between 5V and GND to cause a short-curcuit in case of supplied reverse voltage. With that, I measure between -0.1 to -0.3 V in reverse. It is that I am only not sure if that is less enough to protect the Pi. Mar 14, 2023 at 21:47
  • Your question is misleading. You asked about GPIO which I commented on. The power pins on the header are NOT GPIO. The Pi already has TVS diode. What you now seem to suggest would short your power supply - the result would be unpredictable. I can't recommend this.
    – Milliways
    Mar 14, 2023 at 21:53
  • The power pins on the GPIO header are not GPIO pins, that is right, but I did not say the power pins of the GPIO header are GPIO pins. Shorting the power supply is not unpredictable, it is the wanted behaviour, otherwise the diode clamp - as you recommended - would be useless, as the reason why it works is that (when reverse voltage is supplied) the diode acts almost like a short-curcuit causing the power supply to switch into overcurrent/short-circuit state. Mar 14, 2023 at 21:59

1 Answer 1

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The expansion header GPIO must not be exposed to a voltage outside the range 0V to 3.3V.

The expansion header voltage rail pins have no protection. If you reverse the voltage on the 3V3 or 5V pins the Pi will likely be destroyed.

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    Thank you! Then I will put a Schottky diode in place. Mar 14, 2023 at 14:39

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