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I have an adafruit 16 port servo driver. In the directions on their webpage, they explain how to wire it, as well as connect an external power supply. They mention not to plug the power directly into the raspberry pi, as it can cause a brownout.

The warning:

Don't try to power your servos from the RasPi's 5V power, you can easily cause a power supply brown-out and mess up your Pi! Use a separate 5v 2A or 4A adapter

The RaspberryPi has a 5v GPIO pin, and I was wondering what the chances of causing a brownout were, and how this could be prevented.

It would be easier for me to wire it directly to the Pi, however, I would like not to break it.

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  • do not use the Raspberry Pi as a power supply ... the RPi could become an expensive fuse
    – jsotola
    Commented Nov 9, 2021 at 3:55
  • If the vendor says not to do it DON'T! In fact this is opinion based, if you want an informed opinion you need to specify how much current it needs and what your power budget is.
    – Milliways
    Commented Nov 9, 2021 at 7:47

3 Answers 3

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Despite the convenience, this may not be your best move:

In addition to the warning you referenced in your question, there is another one further down the page:

Switching directions on the servo can cause a lot of noise on the supply, and the servo(s) will cause the voltage to fluctuate significantly, which is a bad situation for the Pi. It's highly recommended to use an external 5V supply with servo motors to avoid problems caused by voltage drops on the Pi's 5V line.

So, even if the supply meets or exceeds the RPi's pwr sup specs, there's still the noise issue. And FWIW, the term "brownout" may be misleading. What happens is that if the RPi's input voltage falls below 4.63 V, a warning is generated, and at some voltage slightly below that, the RPi simply stops working; i.e. not a safe shutdown.

Finally, your question re supplying 5V power via the "GPIO" has been addressed here.

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As long as the power supply is 5V and there is enough for the servos and Pi there will be no problem,

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I disagee - I think that an external power source for servos is the optimal solution. Taking 5V from the RPi is a bad idea. Depending on the servos, they can draw a fair amount of current which the RPi 5V may not be able to deliver and with cause the RPi to stop - perhaps even rubbishing the SD.

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