Tuesday, June 24, 2014

Raspberry Pi power supply

I've been playing with an RPI. So far there's one thing in particular that irks me: its power arrangement. 1A+ @ 5V over µUSB? Really?

No me gusta.

So I've got an idea to design a "cape" (or whatever you call RPI add-ons) to sit on the expansion interface. The board will be as small as possible, but will have a 2.1mm barrel jack and take in 6-12 VDC and supply up to 2A @ 5V regulated by a LM3485 buck converter. Mischief managed.

The board will have a "long tail" DIP jack to mount on the bottom which will allow you to stack other expansion boards on top.


  1. FYI, the RPi limits the amount of current it will supply to USB to (I think) 120mA. On our RPI power supply (using a TDK/Lambda switcher), we have a separate 5V output that powers a Belkin 7 port USB hub.

    1. It's too bad they didn't include a USB port pair of data pins on the GPIO header. It would be useful to bundle in a powered hub with, say, stacking sockets.

      As it stands, though, Pi Power will be able to provide excess power to GPIO connected accessories (using a stacking GPIO header).

    2. Oh, and it turns out that they apparently removed the polyfuses on the rev B boards. So supplying 2A over the GPIO interface should, in principle, easily allow 500 mA on each USB port, plus up to 1A for the Pi and everything else attached. *IF* you're using a rev B.