Multi channel finale high power leds

Thread Starter

Coos Baakman

Joined Nov 25, 2017
6
Hello,
I have 26 3W leds of max 750A, that I'd like to make dimmable using my raspberry pi's 3.3V pwm. I want to use multiple dimmable channels and keep it as tidy as possible. So rather not multiple drivers. I'm having some difficulty finding suitable parts. Mainly because the specs don't match.

I didn't want to built the circuit completely by myself, because I want maximum compactness and minimum energy loss. I trust chips and drivers more for that than I trust myself.

What i'd like to know is:
1) are there led drivers of 750mA constant current that can provide 80V or more?
2) are there maybe chips with multiple channels that can output 80V 750mA?
3) are there any transistors that can switch a 750mA current at 80V?
 

ebeowulf17

Joined Aug 12, 2014
3,274
I'm not familiar with high power LED driver options, but just out of curiosity, why 80V? It seems like an odd, unnecessarily high number.
 

ebeowulf17

Joined Aug 12, 2014
3,274
I guess it could be lower if i arrange the leds in parallel.
I assumed you were planning a combo series-parallel arrangement anyway, because 80V still wouldn't be enough if you were trying to do them all (26 LEDS x 4V = 104V.)

What voltage do you have available for the project? Were you planning to provide 80V (or whatever it ends up being) to the driver/switching circuit, or did you want to start with a lower voltage and have the driver chip step the voltage up as needed?
 

Thread Starter

Coos Baakman

Joined Nov 25, 2017
6
I assumed you were planning a combo series-parallel arrangement anyway, because 80V still wouldn't be enough if you were trying to do them all (26 LEDS x 4V = 104V.)

What voltage do you have available for the project? Were you planning to provide 80V (or whatever it ends up being) to the driver/switching circuit, or did you want to start with a lower voltage and have the driver chip step the voltage up as needed?
 

Thread Starter

Coos Baakman

Joined Nov 25, 2017
6
I have 230V AC available from the plug. Haven't decided yet how to transform it. 6 of the 26 need to be dimmable on a separate channel. All LEDs each need constant current of 750mA.
 

ebeowulf17

Joined Aug 12, 2014
3,274
Wow, these things get expensive when you get into higher amperages!

I found a Linear Technology driver that'll deliver over 100V, but the demo boards are $200, so that's probably overkill.

Searching DigiKey, it looks like you can get 48V output at 1A for about $20, one driver per channel. You could use two drivers with 10 LEDs each and a third with the 6 separate ones.

https://www.digikey.com/product-detail/en/xp-power/LDU4860S1000/1470-2163-5-ND/4488542
 

ebeowulf17

Joined Aug 12, 2014
3,274
Just to clarify, I didn't dig into the datasheet, but I assume the 1A drivers I just linked to can, like most drivers, be set to any current you want up to that limit.
 

Thread Starter

Coos Baakman

Joined Nov 25, 2017
6
I was looking at the MW NPF-60-20, which provides 60W. Could power 20 leds on its own.

I don't think constant current drivers can be turned down. They don't have buttons on them.
 

ebeowulf17

Joined Aug 12, 2014
3,274
I was looking at the MW NPF-60-20, which provides 60W. Could power 20 leds on its own.

I don't think constant current drivers can be turned down. They don't have buttons on them.
That may be true for inline models like the one you linked to. I was picturing board-mount drivers. I just checked the datasheet, and the driver I linked earlier has current set point adjustment with a single resistor - this is typical from what I've seen in my limited experience with other board mounted LED drivers.

IMG_3686.PNG
 
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