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Topic: High Power Led (Read 1 time) previous topic - next topic

xinfinite

Hi,

I want to color controll, with my Mega 2560, 3x a CREE XM-L Color Led
http://www.led-tech.de/en/High-Power-LEDs-Cree/CREE-XM-Serie/CREE-XM-L-Color-on-Star-PCB-LT-2074_120_170.html

Each LED can/will have its own RGBW colorsetting.
(cree xm-l has 4 colors)

My questions:

1. Which powersupply (input 230VAC) do I need for these 3 LED's together

2. Do I think the right way with: With 12 PWM pins on my Mega and 12 MOSFET's between the powersuply and the LEDs, I can dim everything!


Thanks for helping!
Regards,
Jaap

PaulRB

Hi Jaap,

I'm not an expert but I seem to remember reading that pwm to dim high power leds via mosfets can be tricky. A significant amount of charge has to be delivered to or from the mosfet gate in a very short time. If your circuit can't do this, the mosfets to not swtch completely on or off and the result is a lot of heat, which can shorten the life of the mosfets dramatically. There are special mosfet driver chips to overcome this problem.

Paul

jack wp

You may only need 4 PWM signals. If you hook all three boards in parallel. But maybe you want each board to be able to change colors independently. Is that the case?
Good luck, Jack

You might also consider using constant current LED drivers.  There are many on the market these days and many (most?) of them can be controlled with PWM signals.  I suspect that as you develop your design, your LED driver circuitry will evolve into something that's more expensive than just using an off-the-shelf constant current LED driver.

I've used LuxDrive's BuckPucks to drive high power LEDs in a couple of my projects (Crystal Ball Lamp and my chandelier).  However, they're kind of pricy and I'm guessing there are less expensive alternatives available these days.

Hope that helps and have fun with your project!

- Madeline


xinfinite

Thank for your input.

For me it was a difficult issue.
After talking some experts from iPrototype I've choosen the MOSFET ( IRF530 ) solution and purchased a strong powersupply ( TRACOPOWER - TXL 060-3.3S ).
By this, the circuit is very simple and save/strong/fast enough to power and signal all 12 powerleds from the Cree XM-L RGBW.

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