2 Replies Latest reply on Dec 1, 2012 12:14 AM by Drew Fustini

    Raspberry Pi GPIO pin max current

    Drew Fustini

      I became curious recently about the max current per pin on the Pi.  I thought I might share some of the helpful references I found.  I read this discussion on the Foundation's forum:

       

      http://www.raspberrypi.org/phpBB3//viewtopic.php?f=44&t=12498

       

      Two great references were linked from that thread: 

       

      GPIO pads control

      http://www.scribd.com/doc/101830961/GPIO-Pads-Control2

      documentation by Gert which concludes:

      all the electronics of the pads are designed for 16mA.

       

      Understanding Output

      http://www.thebox.myzen.co.uk/Raspberry/Understanding_Outputs.html

      Explains relationship between voltage, current and impedence.  It summarizes:

      A maximum of 16mA per pin with the total current from all pins not exceeding 51mA.

       

      Further explanation:

      When the Pi was designed, they used a figure of 3mA per GPIO pins in determining if the regulator could supply enough current. Hence the simple 3mA limit mentioned before. However, if not all the pins are supplying current then you can divert those pin’s share of the current into the ones you are using. Hence the total recommended current limit of 17 * 3 = 51mA.

       

      BTW, I noticed that Gert has posted other useful Pi technical documents on Scribd:

      http://www.scribd.com/gvanloo8080

        • Re: Raspberry Pi GPIO pin max current
          morgaine

          Those links were very good reading, thanks for that, Drew!  The precise info is very useful.

           

          PS. Enable every single Javascript source on Scribd or the documents seems to omit all kinds of info.  In fact I'm not even sure I'm seeing it all, as some of the articles end rather abruptly.  That site has always given my browsers on all my machines trouble of one kind or another, and completely blank pages or hung access there aren't uncommon for me.