Need help with complex LED circuit

Thread Starter

martnl

Joined Feb 6, 2020
3
I have the following LEDS that I want to glue to a water cooled block (with thermal glue):

100W COB LED (rated @ 30-34V, 3400mA max)
10x LEDS Vf: 1.8-2.4, 700mA max (different colors)
14x LEDS Vf: 3.0-3.4, 700mA max (different colors)

My questions:
What circuit would be best in this case? keeping in mind the fact it's water cooled
How many LED drivers should I use?
could I pull it off with a single driver somehow?
LED longevity is an important issue, so I hope a (partial) parallel circuit would be possible? I can't have all LEDs quitting on me when a single LED dies in the case of an entire series circuit.

and help is very much appreciated!!
 

Dodgydave

Joined Jun 22, 2012
9,873
You need two led drivers, one for the Cob leds, and one 2Amp min rated for the others. Most led drivers can be run in series to save money and time wiring..
 

dl324

Joined Mar 30, 2015
12,264
Welcome to AAC!

What is the voltage of your power source.

LED longevity is an important issue, so I hope a (partial) parallel circuit would be possible? I can't have all LEDs quitting on me when a single LED dies in the case of an entire series circuit.
The lifetime of LEDs is measured in decades when operated within their specs. The failure mode is typically decreased light output vs an open.
 

Thread Starter

martnl

Joined Feb 6, 2020
3
For a LED lamp project (water cooled) I need a proper power supply and electric circuit. There are 3x 34V 3A COB LEDs, 36x 1.8V 700mA(max) LEDs, and 38x 3.4V 600mA(max) LEDs. I have managed to connect all of these to 6 LED drivers, everything connected in series. This is working fine, but I obviously want to reduce this to as few as possible LED drivers, within a decent (series/parallel) circuit. Would this require additional components? The LEDs will be soldered to a 160mm x 80mm PCB.

I am willing to pay for a decent design, so anyone who feels qualified to help, please PM me!

Thanks
 

RPLaJeunesse

Joined Jul 29, 2018
139
Safety is an issue, what is the maximum voltage allowed in the design? I'm betting it could be done with 2 "drivers" and some additional current limiters, but the maximum voltage would be over 100V so definitely not safe without proper insulation and protection. Consider one LED driver that outputs a constant current of 3A at 90-120V DC, feeding the three 100W COB LEDs in series. Now add another driver of 1.9A at 60-80V DC for powering the remaining LEDs. Use 3 simple (custom designed) current limiters, one at 700mA and two at 600mA, to split the 1.9A feed into three branches. The 700mA branch feeds a series string of the 36x 1.8V 700mA LEDs, a string dropping about 65V. For each of the 600mA branches feed a string of 19x 3.4V 600mA LEDs, each string again dropping about 65V. Yes, you need to provide cooling for the custom current limiters, so not the greatest efficiency but probably the simplest approach. Also an issue if the driver wants to force more current than the branches take, it ceases to be a driver and becomes a poorly regulated DC supply. I can think of one other approach that uses a single driver of 6.7A at 60-80V. The solution is not a simple hookup as it needs multiple mixed branches but only small power resistors for current balancing.
 
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