Following on from my older projects i wanted to design a buck converter to work with the Arduino so that I can charge my lead acid and lithium batteries from higher voltage domestic solar panels.
Older thread here
http://forum.arduino.cc/index.php?topic=247320.0
I finally got the time to design, build and test a newer revision after learning mistakes from the old ones.
The unit is based around the IR2184 synchronous mosfet controller. I am using an awesome high power inductor from coilcraft and 60V mosfets. It is a single sided pcb with thermal via's so that it can be stuck inside a metal enclosure or onto a heatsink with themal tape to remove the heat.
After testing the buck converter section is around 96 - 98% efficient which I am very happy with. Unfortunately to make the design cheaper and simpler I used 4 low forward voltage drop diodes to protect against reverse polarity and reverse current leakage. This brings the actual efficiency down to 89 - 94% which is better than most of the chinese rubbish on the market anyway. I may improve this at a later date by using an ideal diode circuit.
Here is a quick video showing it working