Multiple LEDs - drivers suggestions

alesh · Jan 27, 2013

Hello CPF!
I am building a horticulture lamp. However I got stuck at planning power supply.
The lamp will consist of 12 XM-L's, 6 XP-E reds, 12 RebelES royal blues and 18 Rebel deep reds. My intension is to be able drive XM-L, blues and reds separately at 2A, 1A and 700mA respectively. I also need to be able to dim each string by arduino (not PWM in order to keep max efficiency).
The requirements are:
0-2A, 40V min for XM-L's
0-1A, 40V min for blue Rebels
0-700mA, 56V min (or 2x 28V) for reds, both

At first I wanted to buy MW drivers - HLP series but 3 of them would cost me about twice as much as LEDs themselves so I started thinking of another way.
IE buy a 48V PSU and some buck drivers for 1 string of each XML & blue, and 2 strings of reds. Or 24V and 2 strings of XML & blue and 3 of reds. Someone can recommend any buck driver meeting requirements? Or even suitable buck IC's?

Someone can give me a piece of advice which (if any) is the way to go? Or tell me that this is not a good idea and suggest another? I'm looking for affordable price, efficiency and dimmability.

Sorry for my English. Must be kind of funny for native speakers:laughing:

Thanks!

LuxTiop · Jan 29, 2013

My two cents would be to look for a boost topology on your LED drivers, the boost topology gives 90%+ on the driver efficiency. Something like the FLEXblock offered by LEDsupply might do the trick, but there are many other vendors which supply boost drivers. Just make sure to check the maximum voltages on the drivers.

Good Luck

Lumencraft (Matt) · Jan 29, 2013

Hi alesh,

The thing that comes to my mind would be to get 3 Hyperbuck drivers from taskLED. These could run each sting individually and you can use a trim pot for each to get exactly the output you want. You can set the on board trim pot to limit the maximum current each string would see, and then hook up an external 50K pot for the dimming of each string. The only part of your criteria this doesn't fit is that taskled drivers use PWM.

alesh · Jan 31, 2013

Thank you very much for your responses.

These TaskLED drivers look actually pretty well. I really like all the features. They're almost the same price as the MeanWells I wanted to buy at first but these can go up to 80V and 3.2A if I'm not mistaken. It makes plenty of room for adding new LEDs in the future. However it would make the heat loss at the board itself about 25W. It seems to me way too much. Any idea how much power it can handle? Provided that it's properly cooled (attached to a large alu heat sink with forced air convention) ? [Not expecting to use it that hard, just wondering how many LEDs can I possibly add.]
I'm thinking about using a digital potentiometer for dimming via MCU. It should do well, shouldn't it?

a.

Lumencraft (Matt) · Jan 31, 2013

The hardest I have ever driven a taskled driver was to about 95 watts. The only limitation to what they can do is based on the input current. The driver I assume you are referring to with the 80V output is the hyperboost. The data sheet for that one says the input should be under 5A for best performance. So as long as your power supply is variable so you can get the Vin just a couple volts below the total VF of your LEDs the setup you mentioned should work fine.