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.
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)
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.
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?
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.
Waiting for some parts I need.