CC/CV Step Down Converter - High Power - 8-32v In, 1-28v Out

Details

This is the big brother of my 2596 based constant current driver, this one can really handle the jandle with input from 8v to 32v, and output from 1v to 28v and several amps of current.

Step Down / Buck Converter topology, so the output is always less than the input.

Some actual test results!

* 28v at 1.42A out (39.76W), 32v 1.34A in (42.8W), 92% efficiency
* 10v at 4A out (40W), 32v 1.5A in (48W), 83%
* 5v at 4A (20W), 32v 0.833A in (26.6W), 75%
* 10v at 2A (20W), 11.6v at 1.86A in (21.5W), 93%
* 5v at 4A (20W), 11.6v at 2A in (23.2W), 86%

Temperature rise of about 4 degrees per lost-watt (that's Input Watts - Output Watts), so at the 10v@4A level that was about 32 degrees rise.

I did not look at the ripple.

Usage (Setting)

1. Wind both potentiometers anticlockwise about 20 turns, this puts them at the minimums.
   
2. Connect input power
   
3. Use a multimeter in DC Volts mode to measure the output voltage (no load), and adjust the Voltage potentiometer clockwise to get your desired voltage
   
4. Use a multimeter in DC Current mode (make sure your meter can handle the current, put it on the 10A range) to measure the short circuit current across the output (no load), wind the Current potentiometer clockwise to get your desired maximum current.
   

Additional Specs

* Voltage: In 8 to 32v; Out 1 to 28v
* Current: Tested continuously up to 4A as above, I wouldn't exceed 6A
* Maximum output power: tested at up to 40W, achievable output power depends on input to output ratio, current you are drawing, and any additional cooling. In short, if the heatsink hits 65 degrees you need to add a fan.
* Dimensions (including heatsink): 65mm long, 48mm wide, 24mm high
* Potential uses: power supply, led driver, battery charger... anything you need an adjustable current limit and an adjustable voltage really.