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.

3 comments:

  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.

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    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).

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    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.

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