Looking to drive 15-20 high power LEDs

Ok so first off I would like to say that I know almost nothing about microcontrolers and only a little about circuits. So I will start with what kind of LEDs I want to use, they are 10W RGB LEDs no common anode but I figured I could just solder the anodes together to make a common one (not sure though). Here are the specs of the LED DC Forward Voltage: Red 7V ~ 8V; Green 10V ~ 11V; Blue 10V ~ 11V DC Forward Current: 350mA. And I would like to be able to control the color and brightness of each led, connect the driver to wifi (I plan on building an application for the computer to controle all of that), and have a timer to turn them on and off automatically. I understand that this will be pretty complicated with the wifi and all of that but I am ready to learn how to do all of it, so any help I can get will be very helpful! Oh and one more thing please don't suggest other LEDs or a ready made controller because I want to do this DIY.

any help or even where to start would be appreciated!

First off you need more information on those LEDs, the voltage you quoted is too high for them to be normal single LEDs. So a part number or better still a link to the data sheet would be good. Next you will need a constant current driver for each colour of each led, this is going to get expensive.

well if you look at the led it looks like each color has 3 I don’t know what to call it but they are in series so I think that is where the higher voltage comes from. Here is a link to the ebay listing.

http://www.ebay.com/itm/10W-HIGH-POWER-RGB-FULL-COLOR-LED-LIGHT-10mm-dia-200-C-/220772661641?_trksid=p5197.m7&_trkparms=algo%3DLVI%26itu%3DUCI%26otn%3D4%26po%3DLVI%26ps%3D63%26clkid%3D6032449281630465839#ht_2510wt_1027

and about having a driver for each of the colors of each LED is there a way that I could just have like 1, 2,3 , or more and then split up the power and controle each color that way?

Yes they look like they have three of each colour in seriese.

The only way to control more than one LED with the same controller is to put them in seriese. Then they will show all the same intensity and need a higher voltage. You will also need to look to how you are going to arrange the heat sink on these LEDs as it looks like it is not built in.

well if I were to put them in series I could not control the color of each LED could I? and I ordered one of them to look at and see what I can do with heat dissipation.

It looks like what you have there is actually 9 LED's on one chip. 3 reds in series, 3 greens in series and 3 blues in series. You can think of them as 1 real bright LED of each color. This is why the forward voltage is higher than regular LED's would be. You are correct that in series, you can't control them individually. As you Pulse Width Modulate (PWM) each color, you can make that color brighter or dimmer. You can get lots of different colors by adjusting the relative brightness of 2 or more colors.

Be sure to add current limiting resistors and dissipate the heat. Too much of either will let the pretty smoke out and lead you to spend more money.

Lazy Glen

Be sure to add current limiting resistors

No, these are high power LEDs a current limiting resistor doesn't cut it at these powers, you need a constant current driver for each LED you want to control.

ok so I decided that I am going to use 16 of these LEDs, which from what you guys say I am going to need to build 48 constant current drivers. now what if I did multiplexing on them, is there a way I could use maybe 3 drivers (one for each color) or maybe six (cluster them in groups of eight that way I could have two on at a time.) and just direct the power to each LED for a fraction of a second?

Yes multiplexing will cut down on the number of constant current drivers you need. However the LEDs will not be as bright in direct proportion to the on off ratio of the multiplexing. You might compensate for this by driving more than the rated current through the LEDs but you have to see a data sheet to see how far you can push them.

I knwo you dont want to hear abotu other LEDS..

but maybe these are more up your alley? and fit your specs?

10W RGB from LED Engin

http://www.ledengin.com/files/products/appnotes/LZ4-2xxx10-MCPCBapNote.pdf

http://www.mouser.com/ledengin/

however READ the specs carefully..

there are MANY configurations for these 10W LED ENGIN leds.. I only have used the LEDS that come on starboard/pcb/heatsinks..etc

(LUXIII's, P4's, Rebels, Cree & Led Engin's)

depending on your application.. the lens you choose may also effect the outcome.

these vF's might be easier to work with;

MIN: @ 700mA Red 2.00 Green 3.20 Blue 3.20 Amber 2.24

MAX @ 700mA Red 2.96 Green 4.40 Blue 4.48 Amber 3.44

http://www.ledengin.com/files/products/LZ4/LZ4-00MA00.pdf

good luck!

Grumpy_Mike: Yes multiplexing will cut down on the number of constant current drivers you need. However the LEDs will not be as bright in direct proportion to the on off ratio of the multiplexing. You might compensate for this by driving more than the rated current through the LEDs but you have to see a data sheet to see how far you can push them.

well could I have each LED turn off and on say 100 times a second? or would that be to hard to do, or does it matter how many times it turns off and on?

xl97: I knwo you dont want to hear abotu other LEDS..

but maybe these are more up your alley? and fit your specs?

10W RGB from LED Engin

http://www.ledengin.com/files/products/appnotes/LZ4-2xxx10-MCPCBapNote.pdf

http://www.mouser.com/ledengin/

however READ the specs carefully..

there are MANY configurations for these 10W LED ENGIN leds.. I only have used the LEDS that come on starboard/pcb/heatsinks..etc

(LUXIII's, P4's, Rebels, Cree & Led Engin's)

depending on your application.. the lens you choose may also effect the outcome.

these vF's might be easier to work with;

MIN: @ 700mA Red 2.00 Green 3.20 Blue 3.20 Amber 2.24

MAX @ 700mA Red 2.96 Green 4.40 Blue 4.48 Amber 3.44

http://www.ledengin.com/files/products/LZ4/LZ4-00MA00.pdf

good luck!

I will look into these LEDs, but I will also have to take into account the price per LED. Thanks for the links.

yeah they arent cheap..

but they are really bright.. guess it depends on your needs/project. =)

for some of the stuff I do/play with they are some of the brightest that are used.

Do you know how much they are?

you'd have to look at that specific vendor/retailer to get a price.. it varies on the type you buy...

the 10W RGB/RGBA leds "I" use are around the $15.00 mark or so..

ok well thank you! I will look and see which one best suits my needs.

well could I have each LED turn off and on say 100 times a second? or would that be to hard to do, or does it matter how many times it turns off and on?

One hundred times a second is easy to do but it doesn't matter how many time it is turned on an off, what matters is the time it is on relative to the time it is off, or the on off ratio. If it is on for x micro seconds and off for x micro seconds you have a on off ratio of 1:1 and the LED is only pumping out half as much light. if it is on for x micro seconds and off for 4x micro seconds then you have a 4:1 ratio and it is only pumping out one fifth of the light. Because the eye's light response is not linear this is not the same as one fifth the brightness but it is not as bright.

Grumpy_Mike:

well could I have each LED turn off and on say 100 times a second? or would that be to hard to do, or does it matter how many times it turns off and on?

One hundred times a second is easy to do but it doesn't matter how many time it is turned on an off, what matters is the time it is on relative to the time it is off, or the on off ratio. If it is on for x micro seconds and off for x micro seconds you have a on off ratio of 1:1 and the LED is only pumping out half as much light. if it is on for x micro seconds and off for 4x micro seconds then you have a 4:1 ratio and it is only pumping out one fifth of the light. Because the eye's light response is not linear this is not the same as one fifth the brightness but it is not as bright.

ok I get that. thanks for the help.