Lamina Ceramics RGB module

Hi all,

Just wanted to post some LED pron here. Just got my hands on a Lamina Ceramics RGB BL2000 module from digikey....great response in getting it to Oz so quickly, though I'm still having trouble sitting down after the shipping charges.

I quickly tested it on a bench supply, it appears to be configured as 7 facets 3R3G1B making a total of 51 LEDs. I was too scared to try it at full power until I get it on a heatsink. I'll post pics as when it gets lit. It's common cathode, so a little more complexity in the drive circuitry.

phil

Here are some shots I did March of last year:

that's unreal dude. it's only like $13 for rgb, white, blue, green, or red. in the smaller versions. like 108 lumens typ!!?

what's the catch?

that is 2 items now with RGB arrays that use little BLUE?
why is that? with video blue is hardest thing to get light off of, like when we went to 3 CHIP cameras the blue was finnaly rendered better.
and Blue is not a very high ouput led stuff, when using the average light meter, probably because of how the meters work.
so WHY do they use so little blue in these arrays?
i would think they would do the opposite of what we are seeing?
Blue to the eyes is kinda a dark color.

can it run all 3 colors on full? lots of these RGB stuff that i have seen, will do full of any one of thier colors, but full for ALL the colors at once is not suggested, for heat stuff i assume.

Hi Newbie, looks nice. Have a few questions:
- is that an RGB module? If not what power rating is that module?
- what size heatsink did you eventually use?
- lastly, what sort of driver? I was considering a simple PNP driver using BD140s....but would like some more efficient drivers if you know of any.
Vidpro, thats a good question. I'm hoping to use this as an alternative to discrete LEDs in an RGB torch/camera face light. The color rendering is an important factor. Using my existing RGB torch (see rgb torch thread), I've noticed that nice white mixes for a camera phone needs mostly red, a little less green and much less blue....otherwise the white looks too blue. Particularly when I'm trying to mix to match incandescent.....will investigate more when this unit has a driver. Perhaps this module has been white balanced (which white /ubbthreads/images/graemlins/smile.gif?? ) , though I can't find any mention of this in the datasheets.

phil

Leeoniya, Where did you find the RGB for $13?? best I could find was 20.77 + 5 s/h.
Jeff

Lamina has supposidly slashed their prices in half or so if I remember right for certain parts.

Yes, that is the RGB.

I used a huge heatsink, more than required.

I just made my own boost switchers, and then I did it with buck switchers I made.

Re: Lamina Ceramics RGB module - PSUs

Thanks Newbie,

Sorry to bug you with more questions, I'm just starting with SMPS designs and haven't much experience in them. Who'd have thought getting into the LED business would involve so much work on the PSU side of things! There's a bit of advice for new players.

Anyway, did you use three seperate buck/boost switchers? I'm guessing they were constant current mode configuration? If they were constant current, what's the issues in using that configuration with modules sharing a common cathode?

I was thinking of using just two, one to supply near 3.6V for G/B and near 2V for the red, both in constant voltage mode. Then using a small dropping resistor and some power transistors or mosfets can switch the PWM signals to control brightness. As a long term project I'm hoping to use a 16F88 to do the SMPS and PWM control as per Microchips app note AN874 (Buck Configuration High Power LED driver), which uses a 12F675. Surely if a 12F675 can do one SMPS at 2MHz, the 16F88 can do two at 8Mhz. It has two comparators so can possibly do the dual voltage regulation, though that'd leave only one analog input for general use. The chip could then be controlled by serial i/f and be a nice low componenet count solution.

What's peoples opinions on using a dual SMPS 3.6/2V and conventional transistor emitter drivers vs three constant current SMPS for RGB? Any references on people who've done high power RGB to save me a bit of time? I'm sure it'd be a wonderful learning experience.....but hopefully a short one.

Anyone know of references to artwork and ccts (ie complete no brainer construction) to get some simple high current switchers going till this project pans out, and get some experience in SMPS?

Phil

Re: Lamina Ceramics RGB module - PSUs

Dunno which BL2000 you`ve been looking at Phil ;-) ones I`ve seen have had in each `well`, 7 wells, 3 Red 3 Green and one Blue making 49 dice.

Possibly be better asking about drivers in Electronics forum, though switchers tend to be a bit of a black art that no one wants to talk about....

Or have look for specific high current LED drivers on the interweb, have a read at Future Electronics Luxeon ap notes.

For testing good ole LM317s in constant current mode makes a nice stable test bed.

Yes they will take all there rated current all the time, with a big enough heatsink.

No brainer, as your in Oz:
http://www.oatleyelectronics.com/kits/k207.html

HTH
Adam

P.S. looking for somone stateside handy with soldering iron to do me and Craig, Ledmuseum, quick favour soldering some leads on to one of these, if you can help could you P.M. me please.

Re: Lamina Ceramics RGB module - PSUs

Thanks there Adam, as for the calculations I think I forgot to factor in the negative reality inversion that occurs when you do mathematics upside down like we have to here in OZ......you're right it is indeed 49 LEDs /ubbthreads/images/graemlins/smile.gif

I'll give the LM317s a go until I figure out the SMPS stuff.

I did a little more research on the microchip app AN874....its looking simpler than I thought (though I'm sure that there'll be a catch when I get around to actual soldering). The 12F675 has been configured to use it's comparators, the software control is for creating a voltage via PWM (an RC D/A converter) as a reference to the comparator, plus a bit of software trickery to adjust for dropping battery voltage. Fortunately the 16F88 has an internal programmable voltage reference....which can be sent internally to both comparators on it. Perfect. No need to fiddle about continually monitoring the battery voltage and adjustment, probably could do the SMPS with a couple of lines to configure the comparators and reference, then normal code for brightness/pattern control AND have enough analog lines left over for reading pots. Of course selecting the right components outside the chip is the issue. I'm looking into the various equations and stuff about that now. Thanks for the other references.

phil