Keyboard + Tablet Question


#1

Hello guys,

I am currently designing my own keyboard PCB (School-/ Travel-Layout). I would like to use the keyboard with my iPad as a travel/ on the go solution.
Now to my question: Will the PCB require too much power for the iPad to handle if I choose to implement a few RGB LEDs into the design?

Thanks a lot in advance


#2

The “official” limit for powering USB accessories from iOS devices is around 100 mA, or at least that’s what’s suggested to use in QMK. I believe that as long as your board advertises 100mA or less, you can actually use more than that, but above some amount the iPad will detect that you’re using more and stop providing power (I don’t know what the actual limit is; I think it might depend on the iOS version).

If you use an externally powered USB hub or (I think) this powered lightning to USB 3 adapter, the iPad won’t know or care how much power the keyboard uses, but that kind of limits on-the-go usefulness. If the lights use too much power, you could probably power them separately using a battery inside the keyboard or even go bluetooth.


#3

thanks for the information