Dimmable spotlight with high power LED

Projects General Guidance
1

Hello all!

I'm working on a project creating a small dimmable spotlight using a 5W COB led from Yujiled. The plan is to have it and an Arduino Nano Matter both powered by USB-C. I'm pretty new to electronics and I'm definitely in a bit over my head so I thought I would share my plan so far to see if any of the experts here had guidance.

My thinking is that I can take 15 Volts from USB to power the LED through a constant current driver. Then I would split off 5 Volts to power the Arduino which would dim the LED using PWM sent to the constant current driver.

Basically my question is, is this the right approach? Will it work at all?
Do I have the power set up right to even turn the LED on?
Would I be better off just using a MOSFET to control the dimming?
Should I use 3.3V instead to 5 to power the Arduino?
Should the USB breakout be at 18V instead of 15V to give some overhead?
Am I completely bonkers for even trying this?

Here are the parts I've been thinking of using:

Adafruit USB Type C Power Delivery Dummy Breakout

Sparkfun FemtoBuck LED Driver:

Yujileds 95+ 5W COB LED 3200K 5600K - 135XL:

5-30V 12V 24V Buck to 5V Buck Converter Board with 1.8A Output:

Likely powered by a USB-C brick with Power Delivery, something like the Anker 511 Charger (Nano Pro):

And an Arduino Nano Matter, naturally:
https://docs.arduino.cc/hardware/nano-matter/

Here is a schematic of my plan so far:

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Any feedback would be appreciated!

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USB is not 15v, it is 5v.

3

My understanding is that USB-C with "power delivery" can go up to 20 Volts.

From the Adafruit breakout board product page I linked above:

It's perfect for use with USB Type C wall adapters that can provide multiple voltages, the standard offerings are 5V, 9V, 12V, 15V, 18V and 20V.

1 Like
5

No?

Did I get something wrong? I certainly could have. I'm here to learn.

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The receiving device is wired to select the voltage potential.

8

Right, exactly, that's why I included the Adafruit USB-C Power Delivery Dummy Breakout, which lets you select the voltage.

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Just wanted to share what I've been able to figure out, maybe it will be helpful for other.

The basic structure I laid out above worked for me, although with a couple of different components. The Sparkfun FemtoBuck worked, but I think I fried two of them soldering on wires. It also gave a high whine when not at full power (although it seemed to work in the configuration right before I toasted the last one). And I think the USB-C Dummy breakout and step-down converter are different, but equivalent modules.

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USB-C is able to deliver up to 20V with the right charger (the one I specced in my original post is not powerful enough). And specs of USB-C can apparently deliver up to 48V.).

Anyway, I hope it helps other people with similar projects, and maybe as a reminder to other new forum contributors like me that other contributors' confidence does not always correlate with knowledge.

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