I'm wondering if anyone has experience with using a 12V power supply to power the Arduino board.
For the project I'm making (a LED light with R, G, B and white leds) I need 12V to power the leds, so it would be very convenient if the Arduino would work with 12V.
If this is possible I can just use the power connector on the Arduino, and internally connect the leds through the Vin and GND connectors on the Arduino.
The first prototype with 12 1W leds (the final version will have 24 1W leds in total) is now finished and working this way. The problem is however that after a while the Arduino board beneath the power regulator gets very hot (tried it for about 15 minutes now I think)
It's still working, but I'm not sure if it will continue working if I would continue using it this way.
So I would like to know if anyone used the Arduino without problems at 12V before and how hot it got.
The specs on the Arduino (Diecimila, anyway) say that 12VDC in is fine. The regulator chip is a switching type, so it shouldn't get too warm. The rule of thumb for electronics (I've been an electronics hardware tech for 30 years) is that if you can't stand to touch it with your thumb, it's too dang hot.
Still, if you're switching that much power through the LEDs, you'd be better off running separate power to them, versus trying to run that much current through the Arduino Vin circuit board traces (which you risk burning out). If you're handy with a soldering iron, simply add a separate wire from the 'hot' pin of the Arduino power connector to whatever the LEDs are mounted on.
The junction temperature of The MC33269 Linear Voltage regulator is stated to be spec for 150 deg C.
Your observing the classic traits of a linear regular. The efficiency of a linear regular can generalized to be,
Vout / Vin, so 5V/12V is around 42%
At about 170DegC the thermal protection kicks in and shuts down the output. Be careful not to design your application around this. Use better heat dissipation or lower the output current on the 5V output.
