I’m working on a project to use an Arduino to turn on and off around 4 high power 1W LEDs, each using 350mA. From my research it seems I need to use a DC-DC voltage and current regulator to supply constant current for the LEDs.
I plan to supply the LEDs with a 12v DC power supply. It seems I have about two options for powering the LEDs.
Power all 4 in series (3 blue 1 red), total current output on the buck converter would be 350mA, and voltage around 12, assuming 3.2V for the blue LEDs and 2.1V for red. The problem with this option is I’m not sure the DC-DC converter can output that high a voltage to its input.
Power 4 LEDs with 2 in parallel each (Proposed schematic https://i.imgur.com/g8xzo0l.jpg). What I understand is having two blue on one strand will need a voltage drop on that “branch” to be 6.4-6.6V, and then on the other branch to have a current of 350mA I’ve added a resistor to bring that branch current to 6.6V with the red and blue LED. The problem with this solution is I’ve heard the high power type LEDs experience different voltage drops according to temperature and the resistor needed to keep the 350mA current in each branch would be wrong at times and could end up having too high a current on the blue LED branch, I could counteract this by using a lower set current for the whole system.
My understanding with the 2N2222A is to power the base with a 5V signal from an Arduino pin, a resistor about 500 ohms or bellow is fine (I’m still trying to wrap my head around the data sheet values).
What do you think is the best option, or any advice about getting this system working. Perhaps I should use two seperate LED drivers to ensure proper current, or something else entirely? Thanks