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Anyone knows what's the maximum input/output current for the individual GPIO pins?

Perfectly fine if someone is able to point me to the Broadcom BCM2837 datasheet, which I for some reason, cannot find anywhere. (Only managed to find BCM2835, which is for Pi 1...)

SlySven
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Russell Sim
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    Even if your current appears to be within the limits of the device, any fault of the device you're driving can cause substantial current to flow in one or more odd and harmful ways. Consider using transistors controlled by the GPIOs to drive your high-load device. – nanofarad Mar 04 '16 at 11:19

3 Answers3

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Assuming the Pi 3's GPIO pins are the same as the Pi 2's, which I've seen that they are, then the max output of all of the GPIOs together is 50mA. (Source)

This is an interpretation of the rather sketchy documentation, and was actually a design limit of the power supply NOT a limit of the chip (which is NOT documented). The original Pi has an on-board linear regulator which was limited to 50mA, but the B+ and later have a switch mode regulator which can supply more. Electrical Specifications of GPIO

But, the Pi 3 did get an upgrade in terms of USB power supply, so more power hungry USB devices could be used without a powered hub. Whether this applies to the GPIO as well has yet to be seen.

Milliways
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Patrick Cook
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    "Whether this applies to the GPIO as well has yet to be seen." As in burn a Pi and report their findings? Or something a bit more mundane? – Aloha Mar 13 '16 at 01:05
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    @PandaLion98 As in we don't know until the foundation says something about it or someone tests it. I'd be happy to do it when my 3 comes, it wouldn't burn a Pi, it just wouldn't power the device. – Patrick Cook Mar 13 '16 at 01:28
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    So, in practical terms, if you want to run 6 LEDs through GPIO pins at modest 10mA, you are destroying the Pi? I don't mind 16 mA limit per pin, but total 50mA is really pathetic. – Pygmalion Mar 21 '16 at 08:47
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You will not get an official answer.

The party line has always been that you shouldn't draw more than 16 mA from an individual GPIO or more than 50 mA from the GPIO as a whole.

The maximum output of the 3V3 rail is a separate issue. It is more than 50 mA on recent Pis (I have a feeling it may be 500 mA sustained but you would need to check the specs of the converter chip being used on the Pis you are using).

EDITED TO ADD

To the best of my knowledge, based on Adafruit information, the 3V3/1V8 converter (as I think used on A+, B+, Pi2B, Pi3B) can supply up to 1 amp shared between the 3V3 and 1V8 (internal) rails.

joan
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  • How is the combined current available to the 3.3V rail a separate issue than the combined current to the GPIO pins as a whole? Aren't they essentially one and the same in that regard? – Bassinator Nov 07 '18 at 16:38
  • @Bassinator The GPIO aren't connected directly to the 3V3 rail. If they were they would be fairly useless as they would always be high. They are switched on/off/into various other modes via internal circuitry. That internal circuitry is only designed to handle about 50mA. – joan Nov 07 '18 at 17:32
  • `That internal [switching] circuitry is the part that can handle 50 mA` - that makes sense. However, I have also seen from Gert (supposedly one of the original RPi engineers) that the 50 mA limit is _per block_, of which there are 3. Wouldn't this total out to a combined limit of 150 mA? Why not? – Bassinator Nov 07 '18 at 20:45
  • @Bassinator All the accessible GPIO are in the same block (pad 0). – joan Nov 07 '18 at 21:40
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I think you will be fine to assume that that part of the hardware has not been changed (Integrated Circuit Engineers are as lazy as the rest of us so if there is no reason to change things they probably won't!) - besides changing things like the individual pin characteristics means that the software that sets them up ("device tree" files and the interpreter for config.txt ) would have to also be rewritten, which is more work for other people as well...! 8-)

SlySven
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