High Power LED drivers?

Hello,

I am currently working on a LED solution for a party-bus. The plan is to have high powered leds in the roof which are controlled by sound. (Beat detection) The problem I am experiencing right now is that these LED uses 350 mA each. Each unit contains 3 internal LEDs (for each color), so in total each unit draws 1050 mA.

Most LED drivers I have looked at only supports around 80 mA per channel.

My question is if you guys know of any high power constant current LED drivers? (Or another solution for my problem)
It would also be nice if it used some common interface like SPI to control brigthness.

Thank you in advance!

you can just use some cheap motor driver, and hookup the motor output to your LEDs, you can also use the speed control for brightness control:

http://www.robotsimple.com/Motor_Controller_and_Driver/TB6612FNG_Dual_Motor_Driver_Carrier
http://www.robotsimple.com/Motor_Controller_and_Driver/SN754410_Motor_Driver_IC

These two both can do 2 channels, each about 1A. If you can limit your LED power to be a bit less than 1A then you can use these cheap drivers.

You can also use MOSFETs like I have here driving a speaker.
Replace the speaker with your LEDs and use appropriate current limiting for the voltage drop of your LEDs.
Good for high voltage, high current - may need to secure them to a heat sink depending on how much current you have.
With on resistance of .0095 ohm, running 1 amp thru means you're only dissipating .0095W, so they should be pretty cool. (P=I^2 * R, = 1*1 * .0095 = .0095W)

Thanks for the ideas!

I will hopefully get around to try both of these ideas :slight_smile: Waiting for some parts I need.

This

Modified to use a mosfet.

about three steps in he shows a modification so a PWM or digital out can control it. A heat sink and heat sink compound is a must for what you are driving.

The arduino has six pwm outputs. It takes three PWMs per device to be able to set colors. So you could have several devices but only be able to set two colors. The PWMs signal can go to multiple drivers if the lead length isn't too long.

There are some other considerations but first you will want to get one working. Then worry about choosing a power supply to compensate for the horrible automotive power and how to run the cabling.

These are interesting.

Why wouldn't it really be possible to just use a strong NPN transistor and PWM to control the brigthness with these high powered LEDs?

Controlling the max current with a 5W resistor?

On a side note, each channel would only draw 350 A max right? 1 channel for each color in the LED.

MOSFETs have the benefit of having really low turn on resistance, so they don't get hot like NPN transistors.
$1.53 each for 10, TO220 package is easy to work with.

Still need current limit resistor calculated from voltage supply, LED voltage drop, and current.
Unless its built into the high power LED package. Anyone seen a link or a datasheet?

Alright, that clears that up :slight_smile:

These are some really cheap ones I wanted to test out:
http://www.dealextreme.com/details.dx/sku.4530

Hopefully they work as intended, if not, well...they were cheap so it won't be a big issue.

Thanks for all the ideas, hints and help.

You might be able to get away with these

$1.63 for small qty at mouser

I'd probably limit it to 1 device per LED tho, use 2 outputs per color to drive your LED module.

With a 5 V supply, you'd be limited to 1 LED per IC, each color will need its own current limit resistor. With V=IR, or R=V/I -> (5V-2.5V)/0.350A = 7.1ohm (use 7.5 as closest standard
so real current will be max of (5-2.5)/7.5 = 0.333A
P= I^2 * R -> .333*.333*7.5 = 0.83W
and do similar calculation for the the 3.2V devices
So you'd probably want something rated for at least 2W to keep it from burning up if it ran all the time and wasn't ventilated very well, such as

Since these are common anode (from the user comments) you can't really put them in series to take advantage of a high source voltage. That would be one advantage of discrete parts - can wire up 3 or 4 in series with a 12V supply and drive with 1 line.
Look at some of the discrete parts here
http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=%2Fleds.htm
LEDs are $1 each in small qty, less as you get more.
The tradeoff is more wiring to create the strings of 3 or 4, the advantage is far fewer current limiting resistors needed, so you have to make the labor/material cost tradeoff.