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What is the Max Current to Draw from 5V Pin Safely?  Is it 40-50mA like the digital i/o pins?javascript:void(0);

[Reply #1 on:]

one variable is what your using to power the arduino in the first place

[Reply #2 on:]

What is the Max Current to Draw from 5V Pin Safely?  Is it 40-50mA like the digital i/o pins?javascript:void(0);

No it's limited by the power source the arduino board is using. USB can provide about 500ma limited by the on board thermofuse. If on external power maybe a little more depending on the exact voltage you run the external power (or Vin) at. The basic board consumes about 50ma or so, the rest is available at the 5V pin.

Lefty

[Reply #3 on:]

I have a AC-to-DC 12V, 1amp rated wall-wart.  With that plugged in to the barrel jack is it safe to draw 950mA from the 5v pin?

[Reply #4 on:]

I have a AC-to-DC 12V, 1amp rated wall-wart.  With that plugged in to the barrel jack is it safe to draw 950mA from the 5v pin?

Probably not. The 12v feeds the on-board +5vdc voltage regulator chip that then feeds the shield 5V pin as well as whatever the board itself requires. The regulator I think is rated at 700ma max, but can be limited to even less due to the heat loss of from cutting from 12V to 5 volts. It's better from a maxium current capacity to power the board with 7.5 to 8 vdc as it will allow the on board regulator to run cooler at any current demand placed on it.

Lefty

[Reply #5 on:]

oh I didn't realize.  thank you!

[Reply #6 on:]

Since you're using the barrel jack for power, if you need more you can draw it from the VIn pin.  When the arduino is powered via the jack, VIn gives you a direct connection to your supply and bypasses the voltage regulator.  Just don't forget to connect it to a regulator of your own to drop it down to 5v.  I believe you can go as far as 1A before you need to start worrying about overheating things.