I'm going to power my Arduino Mega with a 11.1V 3-cell Li-Po battery pack. I've hooked it up and let the board run for about an hour and I accidentally touch the voltage regulator on the mega board. It left a burn on my finger. Is this a problem?
Would it be a good idea to switch out/replace the default voltage regulator with 3-Terminal 5V 1A Switching Voltage Regulator? I read about this in another thread. The voltage regulator on the board now dissipates excess voltage as heat, and that's what it was designed for. I'm just worried that it will get too hot. I measured the voltage output of the battery at full charge, and it discharges at 12.3V. This board could be on for hours at a time.
The voltage regulator is dropping 11 volts to 5 volts; those 6 volts have to go somewhere - and there they go; as heat. The MC33269D has a dropout of 1.0 volt, which means your input needs to be at least 1.0 volt higher than your output. If you run this regulator on 6-7 volts (say, a 7.2 volt pack), it should run much cooler.
Yes, that could work, too; adding a heatsink as Casey Gross suggested is also a good idea. Reducing the voltage input is probably the simplest. If your system needs the 11 volts, consider splitting the pack into two packs (one of the packs would need to be a 6 volt pack or higher, of course), and running the Mega from the center tap off the larger pack.
The other option is a switching DC/DC converter. These can be very efficient and not waste the energy as heat. Here is one I have used but there are many others:-
If your voltage regulator is getting very hot in normal use, then you must have a short of some kind or a very high load connected to your board. You may want to look at regulators like below, as they are apparently very efficient.
Came across this post earlier today while trying to find ways to fix my arduino and actually ended up switching out the regulator and wrote a blog about it here:
Came across this post earlier today while trying to find ways to fix my arduino and actually ended up switching out the regulator and wrote a blog about it here:
Interesting article, but the web page is poor with hard to read text.
Note: The 7805 does not have a "big heat sink" - on the contrary. The use of voltage above 12 volts will lead to considerable heat-up with the original (superior) and the substituted regulator . When the data sheet says "20 volts" it addresses OTHER limitations. The heating is something quite different. You can of course use 20 volts input, when drawing 30mA or so...
It's probably worth pointing out that even at a 'medium' temperature for a voltage regulator (say 60 degrees C) it'll possibly burn your finger, but not necessarily need a heatsink.
Human digits aren't really good at measuring temperature...
Google LM2574 - it's a tiny (dip8), 0.5A (higher available) step-down voltage regulator, also in adjustable version, which only needs 5 or 6 components to run, has low dropout voltage (in range of 1.23V or so), and high efficiency (over 70%)
I'm using it in my current project to reduce car DC voltage down to 7V before feeding it to arduino.
