Using high power LEDs with a 27ch controller

I'm fairly new here, but have been reading a lot here and on a handful of other boards for a few months. Have learned a lot, but some info has been hard to come by.

What i would like to do is use a controller that's normally used for "dumb" led light strips with a high power LED like this:

http://dx.com/p/10w-500-lumen-multi-color-rgb-led-emitter-metal-plate-140-degree-44043

I want to hook it to the PWM channels on the controller, so i can change colors/brightness etc. So first, is it even possible to hook the PWM outs from the controller directly to the led, or do i need a driver between the two? I thought i understood that it didn't need either a driver or a resistor, since the controller is taking care of it.

How do i calculate how many amps is being drawn, just add up all of the max forward currents for each R G and B led? In this case, that page says working current is 350 ma, is that the max current?

This particular LED has six leads, if i understand right, it won't matter if a controller i want to use it with requires one or the other because this led can be either common anode or common cathode, depending on how i hook it up , is that right?

Thank you!

Looks like that controller eliminates the need to use a driver.
The link you gave with the LED you want to buy, says absolutely nothing about the LED. I dont know if 350mA is the starting current or the max current, probably starting current?
Also they do not state whether this 350mA is per colour or for the total LED?
There are clearly 9 dies on the LED, so you can only assume that each row represents a colour, with two leads per row, positive and negative so that each colour can be turned on separately.
That means that you only need a 3 channel controller, so 27 channel is overkill unless you plan to use it on something else in the feature or already have one.

I don't really understand your question about common anode or cathode, but an LED is essentially a diode, that means if you wire it wrong and your voltage goes higher than the maximum reverse voltage, you blow it up.
From the channel specifications you provided:
R = Red Negative
G = Green Negative
B = Blue Negative
COM = Common Positive
That means wire all the positive terminals to the "COM" port and you should be able to figure the rest out yourself.

Hope this helps a bit, your post is rather confusing.

My guess from the look of the board is that it's just PWMing MOSFETs, each rated at 2Amps max pass-through current; so basically the same as you turning on and off a switch really fast, nothing more or less. So the driver situation would be the same as if you were wanting to drive the LED by itself, just with this DMX-controlled board acting as a power switch.
Cheapest and easiest constant current method would be to use a single AMC7135 on each line you want switched; they are 350mA constant current sinks, which appears to be the recommended drive current for this LED. LED has 3x chips in series for the three colours, red chewing 7-8V @350mA, green and blue using 10-11V; if you chucked a 12V power source on there with the AMC7135s it should work, but the red line in particlar might get a bit toasty as there's a 4-5V differential. Could maybe try a 9V regulator on the red circuit to get it closer with less losses as heat / overloaded circuits?

Yes you could set it up as either common anode or common cathode, or neither common. Neither anodes nor cathodes are tied together in that package, which is the case with 4-pin packages.

I have been looking at the controller i mentioned for a few months, a few hours after i made that post, i found some info that implied (but didn't say outright) that the controller is constant voltage, but the LEDs are constant current, and so won't work together. Does that sound right?

I found a different controller:

http://www.aliexpress.com/store/pro...WM-Decoder-350ma-output/701799_509913417.html

That is a constant current decoder, needless to say i didn't sleep last night and spent the time reading and reworking everything for this project. Does that sound reasonable- are these standalone LEDs always constant current devices, or are some constant voltage? Does the new driver i listed above sound like a better solution? It's more expensive, it only drives 16 channels (vs. the original 27), and it only drives them to a max of 350ma/ch.

AJ Botha,

Thanks for saying, here is a link to another LED i was looking at, this one has more info about current and voltage requirements

http://www.ebay.com/itm/9W-RGB-LED-...996?pt=LH_DefaultDomain_0&hash=item19c7242c34

It mentioned 350ma for each color as driving current, and that matches with the 350ma per channel on the new controller i listed above, so it should be ok (?)
Also, that answers my question about common anode/cathode. I guessed that the C meant common Cathode but wasn't sure. Also, i need to drive as many of
these high power LEDs as possible from one unit, that's why nine channels.

Rogue,

Thanks for that suggestion, i did look at the amc7135, it looks like it might work as part of the solution, but not something i'd be able to work out- my knowledge of electronics is very basic- i also need to control the levels of each channel through DMX, which the board i mentioned will do. I spent quite a few weeks working out how to engineer it myself using something similar and an arduino for the control, but, like i figured before i started, it turned out to be far more technical than i could manage, especially since i need DMX control, it looks like more added circuitry would be needed to drive the LEDs, which is beyond my abilities.

After looking more into it the amc7135 seemed a good option. I saw this page

http://dx.com/p/amc7135-1050ma-regulated-circuit-board-for-diy-flashlights-10-pack-1885

Which are drivers that each have 3 of those chips (350ma for each). Dimming the LEDs
(PWM) via DMX is still a problem, i'll have to read a lot more.

Yes, I agree the first controller is constant voltage output, with PWM. The output voltage will be whatever power supply you use. And the second one is constant current, which is exactly what your LEDs want. It looks like AliExpress carries both drivers, maybe cheaper for the first one than the other place, depending on shipping.

If you are looking for cheap, I'd use the first driver with resistors to set the current in each string. AliExpress have a 120W 12V supply for under $10. It's adjustable too, so you could get two, set one a bit high to run the green and blue strings, one lower to run the red strings. You could buy a bunch of 5 ohm, 1W resistors pretty cheap, and adjust the supplies to give you the right current in each string

You might get away with a bunch of AMC7135s. If you do that, put a 10-ohm, 2+ watt resistor in series with each of the red LED strings to relieve some of the power from the AMC chips. Keep in mind though, that the AMC7135 cannot handle 12V. It's true that the LEDs drop the voltage into a safe range for the AMC, but I would not be comfortable saying that they would survive being turned on and off hundreds of times per second (which is what PWM is) for very long. The driver you mentioned has three chips on it, but they are all tied together, so you can only run one group of LEDs at 1050 mA, unless you hack up the board to separate them.

If you are looking for clean and easy, the second driver looks like it is purpose built for exactly what you want to do. Just hook up power supply, LEDs and DMX, and you're done.

I think the second LED you posted is probably the same as the first one, just a fuzzier picture and an extra $2 plus postage!

By just adding a resistor to the 27 channel version, it will be both constant current and constant voltage? It seems that would be less expensive if that works since i need at least 24 channels, so i'd need two of the second (16 channel) controller. If simply adding the resistors amounts to the same thing, it might be better i think. So i can just pick a voltage, say 12V to plug into the 27ch controller and use a resistor on each channel to bring the voltage within tolerance of the led hooked to it?

I'll keep this info regarding the amc7135 in mind if i need to go that way at a later point, thanks for mentioning those details.

robisais said:

By just adding a resistor to the 27 channel version, it will be both constant current and constant voltage?

Click to expand...

Not constant current, more... restricted current. There'll be some variance in the current depending on the LED temperature etc., but it shouldn't be too bad. Definitely not ideal, but should do the job.

FYI, you can get 10x 350mA 7135's for about $1.90 including shipping here. Note that you can also get the newer 380mA versions, which in your case you don't want.

Thanks for all of the help!