Power Arduino through 5V pin

Discussion in 'The Projects Forum' started by ebeowulf17, Jan 15, 2015.

  1. ebeowulf17

    Thread Starter Active Member

    Aug 12, 2014
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    So I've got some projects I'm playing with right now that involve 24VDC and also an Arduino Uno. My 24VDC supply (re-purposed from the guts of a laser printer) also provides 5VDC (maybe 5.2.)

    I'd like to power the Arduino directly from that instead of using batteries or a separate power supply, but I can't find info on its power tolerances.

    The regular power inputs need 7+ to regulate down from, and the 5V pin bypasses the onboard regulator.

    Anyone know if 5.2V is likely to somehow upset it? I realize it will change my default Aref, but any other reason not to do it?
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Look at the ATmel data sheet for the processor. IIRC, it can go to 5.5V.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    You will be fine using the 5V supply. You can add a properly biased 5.6 v Zener to make sure you don't damage your arduino.
     
  4. ebeowulf17

    Thread Starter Active Member

    Aug 12, 2014
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    Good news! Datasheet says 6.0V. More forgiving than I thought.
     
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    Now check some other things.

    Can the on-board voltage regulator chip tolerate 6V on its output pin when its input is not connected?

    Can the USB interface chips tolerate 6V?

    What happens if you have 6V to the board and you plug-in 5V from the USB?

    Can the 6V backfeed into the USB?
     
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