Dimming a high-power LED

Projects General Guidance
1

Hi!

I'm working on a project and part of the project requires the dimming of a 10W LED. I'm familiar with the PWM technique used with lower power LED's but I'm unsure on how I would go about dimming such a high power LED? I will be using a constant current driver to power the LED. The LED is rated at 9-12v with a current of up to 1.1A. Will reducing this current reduce the brightness of the LED? Or will reducing the voltage reduce the brightness of the LED? Sorry my physics knowledge is very limited. Thanks very much in advance!

James

2

Yes reducing the current will reduce the brightness.
You have to use a constant current drive circuit that will allow you to switch it between the set current and zero. Then you PWM that.

4

AFAIK the efficiency of power LEDs decreases with decreasing current. Best efficiency is achieved with a PWM controller.

5

Thanks to all that replied, so if I purchased a controller such as this http://www.gearbest.com/development-boards/pp_140613.html?currency=GBP&gclid=CLGzy86OlckCFQX3wgod0rMHtw , could I then hook this up to the LED instead of a motor as described and then somehow take off the pot and wire that up to the arduino to digitally change the resistance?

6

I would never buy anything where the "makers" scratch out the chip's numbers.

7

Oh okay, thanks. But in theory for a similar product, would that be valid? Thanks for all your help.

8

Well there is a comment about driving an LED at 300mA but that is not answered very well. It depends on if the current can be set and if so how. If that pot sets the current then how are you going to emulate that pot, it will depend on what it does. Also a stepping motor drive with three FETs looks a bit odd to me.

In short I don't think there is enough information on that page to tell if it is sutiable for what you want.