External power from a regulated source

Development Boards Arduino
1

Looking at the schematic (http://arduino.cc/en/uploads/Main/ardui … ematic.pdf) and reading various references (including http://arduino.cc/en/Main/ArduinoBoardDuemilanove), it would appear that the Duemilinove can get power from three sources.

  • The first is from the USB

  • The second from the external barrel connector (7-12V)

  • The third by feeding in a regulated supply of 5V INTO the 5V connector

    • It is this last method that I am unsure about. Nothing I have read says this is directly allowable, and yet there are allusions to this. This statement in the Arduino spec sheet is not exactly clear, but certainly could be read as the 5V pin could take an external regulated 5V supply.

    5V. The regulated power supply used to power the microcontroller and other components on the board. This can come either from VIN via an on-board regulator, or be supplied by USB or another regulated 5V supply.

    I wish to power the Duemilanove from the regulated output of the SFE lipo charger/boost regulator (http://www.sparkfun.com/products/10300) connected to the 5V terminal of the Duemilinove.

    Will this work?

    2

    I’m not looking at a schematic but it should work. The only problem i would see is that you shouldn’t power a regulator on its VOUT side.

    3

    Works fine for me with an Uno. I’m using Sparkfun’s neat little [breadboard power supply. My project was warming up the on-board Uno regulator a bit (it doesn’t have much of a heat sink), so I changed to the external power supply. The way I read that excerpt from the spec sheet, this is exactly what they mean, even if they don’t make it perfectly clear. I don’t know of any reason it wouldn’t be OK.](http://www.sparkfun.com/products/114)