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in my project I have to power the Raspberry pi over the GPIO port. I know that the voltage must be regulated to 5V. My input is 24V so I have to convert it to 5V. I'm currently designing a PCB with the power regulation in it. So after research I find 2 chips to do this job: the LM2596 or the 78S05. But I don't know which one use.

My questions are the followings:

  • Which chips is the best and why?
  • If I power the Raspberry pi over the GPIO pin will be I always able to connect USB devices?

Thanks in advance!

Majonsi
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2 Answers2

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Personally I would use neither.

I suggest you use a UBEC.

They cost about 1GBP and will convert a voltage in the range 26-5.5V to 5V.

I use UBECs to power some of my Pis via the expansion header.

Yes, you can power USB devices from the Pi if the Pi is powered via the expansion header.

joan
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You can power the Pi through the 5V pins on the expansion header, but should consider isolation (although if you are satisfied with the safety of the supply this is not strictly necessary). See Raspberry Pi Power Limitations.

You cannot use a linear regulator (most of the energy would go as heat), but a switch mode supply would be suitable. The LM2596 is one such, but you mention a "chip". If you purchase a module which uses this (or a similar) chip it should work. Trying to build your own from a chip is not feasible. You would be better to get a module DESIGNED to generate 5V, rather than an adjustable module.

Joan mentions a UBEC and these are suitable, but rather specialised for models. UBEC tend to be more expensive (at least round here) than other modules. 1GBP (1 Giga British Pound?? - not a unit I am familiar with) seems high ;-)

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Milliways
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