I've been reading the forum for some time now but this is my first post and as I don't know anything about electronics <.<, please be nice ; )
So what I'm trying to do is essentially to drive 14 strings with varying numbers of 1W LEDs (2 to 10 to be precise). The strings will need voltages from ~3V to 24V and all LEDs need a current of 350 mA. I would like to be able to regulate the brightness via a computer that communicates with an Arduino Uno connected to a TLC5940. The LEDs will get their power from a CAT4201 from ONSEMI.
I was able to hook up the TLC5940 and the Arduino nicely. The system also accepts commands from my computer but now I'm stuck with the high powered LEDs as I don't have a clue what to do with the driver. I saw that most of the people use a CAT4101 to drive the LEDs, but this requires the use of a resistor to limit voltage and I would like to prevent that. After digging a bit I found the CAT4201, which is a step down LED driver for up to 350 mA which sounded perfect. I added a link to the data sheet at the end.
So my questions are
Does the following schematic work (I'm a bit worried if I wired the CTRL correctly)? Input would be directly from a Meanwell 70 W 24 V power source and PWM would come from the TLC5940 through the R2 to CTRL.
Would I need a transistor between the TLC5940, which is a current sink, and the CTRL?
If it works can I add any number of LEDs (not exceeding the 24V) with each requiring 350 mA to the output?
In the CAT4201 data sheet it is noted that a 2 Ohm resistor should be added between the 24V input and C1 to protect against too high current. Is it really necessary as I would like to keep the efficiency high and this would dissipate 2.5 W (if I calculated correctly)?
Is the Meanwell power source of the correct type (there seem to be infinite different variants <.<) and 70 W enough headroom if there are 60 W of LEDs?
Thanks in advance!
DataDatasheet CAT4201Datasheet Meanwell NES 75-24
LEDs 2.3 to 3.5 V, 350 mA, 1 W
/P.S sorry for the strange schematic. I tried to do it with EagleCADs free version but it kept crashing when I wanted to save (very frustrating >.<).