Can this be done?

As some know, I'm a little out of my element with electronics. But I'm relearning some stuff forgotten decades ago and learning some new things too.

That said, here's why I started this thread. And this is entirely hypothetical at this point. Not to mention it's probably been done and you folks are probably tired of answering questions about it.

I have a power supply. Let's say, 20VDC~7A. So, 140W. And one of those 117W Cree COB led with a Vf of 34V (if memory serves).

Is it possible/feasible to power the COB with a CC buck/boost AND be able to control it using arduino based PWM for dimming?

Can it be done? What are the drawbacks, dangers, etc? A better way altogether?

I know I can purchase a controller to do exactly this. But I tend to go the DIY route whenever I can. And if it saves a few bucks in the process, great!

Thanks!

by DangerToHimself
June 19, 2017

Perhaps some of the units you mentioned are confused? Most the Cree LED flashlights use 3.7 volt (18650) batteries and don't give off anything near 100 watts. Maybe you are meaning to say 117 LUMENS? big, big difference. If you shop at Ebay, you can buy these flashlights very cheap (~$10.00). A 100 watt LED is nearly impossible to imagine. A replacement LED bulb for a 60 watt incandecent bulb only uses about 9 watts. Maybe you could look closer to what units (watts, lumens, volts, candle power). Good luck!

by Russ7411
June 27, 2017

Much appreciated, but my post has nothing to do with flashlights. There are 117W Cree COB (chip on board) LEDs.

These are but one example. http://www.cree.com/led-components/products/xlamp-leds-integrated-arrays/xlamp-cxa3070

by DangerToHimself
June 28, 2017

So i did something similar for smaller loads

https://e2e.ti.com/support/power_management/lcd_oled_bias/f/954/t/323072

I think you should forget about the CC and just supply the VF for the LED then make sure your PSU can drive the req.current. Basic discrete pwm with a CC isnt easy.

by Silentknight951
July 06, 2017
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1 Answer

Answer by DangerToHimself

Found info on it after a lot of searching. Can be done at the risk of killing the boost converter. So, not feasible.

+1 vote
by DangerToHimself
June 22, 2017
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