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Topic: Ardunio full power useage and max power input. (Read 540 times) previous topic - next topic


Hello, I'm trying to power both a Raspberry Pi and an Ardunio off the same UBS connection.
The connection is 5v@900amps

Just wondering about the power draw of the Pro Micro including the max amount of amps i can pump into it.

Making a PCB to control them both so using things like common ground and power will make it a lot easier.


Sep 02, 2015, 04:12 pm Last Edit: Sep 02, 2015, 04:12 pm by aarg
What do you mean, "pump into it"? You don't usually pump current into a micro. You apply a voltage.
  ... with a transistor and a large sum of money to spend ...
Please don't PM me with technical questions. Post them in the forum.


You don't "pump power" into a load.    From Ohm's Law, Current = Voltage / Resistance.  

900mA = 0.9 Amps is the limit  of your USB port.   If you draw more current than that, it will shut down,or the voltage will drop, or it will fry.   (A USB port will usually just shut down, but I wouldn't intentionally try stressing it.)  

We don't generally don't know the resistance/impedance of the Arduino or Raspberry Pi, but we could measure the current.   The current will depend on what's attached...  i.e.  If you drive a bunch of LEDs with the Arduino, it will "draw" more current.    Sorry, I don't know how much current it draws with nothing attached.    The Internet tells me the Raspberry Pi draws a little more than 300mA with nothing attached.


A raspberry Pi will take about 600mA and an Arduino about 40mA.

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