# Technical Evaluation: Lamina Atlas



## evan9162 (Oct 27, 2007)

I was ordering a few parts and saw that Mouser also happened to have the newish Lamina Atlas in stock. I figured I'd pick one up and see what it's made of.

The Atlas is basically an improved version of the BL-4000. It's spec'ed to output more than the BL-4000, with improved efficiency. Let's check it out:







Here it is next to what it competes with in terms of specs - the Luxeon V star. They are about the same size. Both use a quad-die, series-parallel configuration, resulting in nominal current level of 700mA, and typical Vf at that current level in the 7V-ish range. If you're familiar with the BL-4000, then a couple of differences are immediately apparent. If not, here's a picture of the BL-4000 so you can compare:






The Atlas has a silver ring around the optical dome (which is made of clear silicone). The optical dome is also substantially taller. This ring may be to allow optics to rest on the Atlas without the risk of damaging the part, and the taller dome may improve performance with certian optics as well. Finally, you can easily see the individual dies of the Atlas, so it appears that they are also using a conformal phosphor coating, which provides better off-axis color quality.

You can see how widely spaced apart the dies of the Atlas are, especially compared to the tightly packed dies on the Luxeon V. This will mean that the Atlas will not focus well in normal sized reflectors - if you thought the "donut-hole" problem was bad with a Luxeon V, it'll be much worse with the Atlas.

Here is a close-up of the 4 dies with only fractions of a mA of current flowing:






Close up of the two top dies:







You can see that each die is using two bond wires on each contact. There are no less than a dozen bond wires holding things together electrically. In addition, you can see the top contact pattern on the LED dice. This contact pattern is unlike any I've seen so far between all the LEDs I've worked with, including the XR-E/Seoul P4, Luxeon I/III/V, or K2/Rebel. It would be interesting to know who they're sourcing their dies from. 

Let's see what this thing's made of...

First, beam profile:






Pretty average beam profile. From a distance, pretty much equivalent to a Luxeon V. Of course, up close things will be substantially different.

Here's the raw performance data:

```
Current (mA)	0.1	30	130	310	670	980	1260
---------------------------------------------------------------------
Vf		2.5*	5.29	5.79	6.32	7.08	7.61	8.07

Watts				0.75	1.96	4.74	7.46	10.17

Lumens				49	106	193	248	285

Lumens/W			65	54	41	33	28


*No light was produced, which is unusual.  Every other LED produces some
small amount of light at this current level.  The low Vf is probably a
result of current jumping across the junction without actually producing
light.
```

Next, the Vf curve:






The series-parallel arrangement already assures a Vf higher than the single-die devices we're used to. However, these dies don't maintain a low Vf very well at higher current levels. This significantly reduces efficieny at higher current levels.

Next, luminous output:






While the Atlas is outputting more at a given current level than these other LEDs, keep in mind that it (like the Luxeon V) requires twice the voltage and thus twice the power to do so. So while the output might seem good, the efficiency really isn't that great. I've had poor luck with Lamina products taking high levels of overdrive without suffering damage, so I didn't bother pushing it past about 1.2A.

Next, efficiency:






The Atlas is hanging out in Luxeon V territory for efficiency. Notice the efficiency dropping off faster than a Luxeon V at higher current levels. This is due to the Vf which increases dramatically at higher currents, vs. a Luxeon v who's Vf stays relatively flat as current increases.

Finally, "droopyness":






The efficiency of the Atlas drops of a lot more than comparable LEDs. Even the Luxeon V maintains its efficiency much better. And when you consider that each die of the Atlas is receiving only half the current of the single die LEDs (like the Rebel, XR-E, Seoul P4), you can see that the dies in the Atlas have a pretty big performance deficit.


So, are they worth it? For me, no. The Atlas costs about $16, but only offers (at best) previous generation efficiency. The widely spaced quad dies in the optical cavity make it hard to focus in small reflectors. You can get almost the same level of output (close enough to not matter) from an XR/E, Seoul P4, or Rebel-100; each of which will be over twice as efficient, have a much smaller source size making optics and reflectors perform better, for less cost (even for the premium bins). Plus, the Atlas only comes as a "star", limiting the use in certian smaller form factor applications. We are also starting to see fierce competition in the multi-die, high output LED market from competitors like Edison Opto, Osram, and even Seoul, all of which offer higher output levels in the same package size, and better efficiency.


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## jeffosborne (Oct 27, 2007)

Excellent report, evan9162! Thanks for the insight into this part. Your photos are quite good, what are you using to take them?

Cheers,

Jeff O.


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## Erasmus (Oct 27, 2007)

jeffosborne said:


> Excellent report, evan9162!


I second that! Great work, Evan!

When reading this review I think it is uninteresting for people on this forum. Low efficacy and really a PITA to focus it in a flashlight-size reflector. 

On the other hand it would be great if Cree could make this type of LED, with 4 chips mounted as close as possible to each other in a series-parellel config. Imagine the four Q5 binned chips, that would give at least 428 lumen at a power consumption of around 5 watts. That setup would be more than twice as efficient!


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## evan9162 (Oct 27, 2007)

Canon PowerShot G3 (4 years old now)

For the macro shot, I use 3 macro lenses stacked + a reversed 55mm SLR lens.

This is what gets attached to the front of my camera:


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## evan9162 (Oct 27, 2007)

Added a close-up of the top two dies to better show the top contact pattern.
Also added the actual performance data (forgot to do that in the original posting)


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## tvodrd (Oct 27, 2007)

:thumbsup: and thanks! (Why I can't stay away from this place!)

Larry


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## MikeRD03 (Oct 28, 2007)

Hi evan,

Thanx for your report. I read enough to know that the Altas is obsolete for me 

cheers,
MikeRD03


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## Anglepoise (Oct 28, 2007)

Thanks Evan,
Great stuff here as usual.


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## easilyled (Oct 29, 2007)

Many thanks for the valuable input. :thumbsup:

Threads like these are so helpful in determining choices.


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## VidPro (Oct 30, 2007)

questions boss?
i was looking at the atlas only for the purpose of RGB, because its 6 wire RGB, not common connection stuff.
so we already know the lumen effiecny would be rotten on that, but its all about the color.

and in the picture, and i see it in your picture too, there is a Black Blob on the solder pads of the star, i think on the RGB there is 3.
What the heck is it? see right there next to the numbers on the atlas chip.


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## 1 what (Oct 30, 2007)

Great overview.
Thanks.
Good to know somebody else uses Mouser.


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## evan9162 (Oct 30, 2007)

VidPro said:


> questions boss?
> i was looking at the atlas only for the purpose of RGB, because its 6 wire RGB, not common connection stuff.
> so we already know the lumen effiecny would be rotten on that, but its all about the color.
> 
> ...



I believe that's a protection diode. It may serve as reverse voltage protection, ESD protection, or both.

Since there's only one circuit in the white, there's only one protection diode needed. Each of the 3 RGB sets needs seperate protection, so there are 3 present. Like previous products, lamina uses a common board with common circuitry between the white and RGB products, and just doesn't use the other traces on the white products.

I haven't bothered checking if the protection diode is in series or parallel with the device. If it's in series, it may explain why the Vf gets so high - but, I very seriously doubt that's so, since it would also mean all the current would be passing through that diode - which is a lot of power for such a small device to dissipate (1/2W to 1W). So I'm pretty sure the device is in parallel with the LEDs.


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## evan9162 (Oct 30, 2007)

1 what said:


> Great overview.
> Thanks.
> Good to know somebody else uses Mouser.



I use Mouser and Digikey, because neither has decided it should carry all of the parts I need for my various projects. It's roughly a 70/30 split between Digikey and Mouser respectively. It's a pain to source parts between two suppliers.


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## VidPro (Oct 30, 2007)

evan9162 said:


> I believe that's a protection diode. It may serve as reverse voltage protection, ESD protection, or both.
> . . . .
> .


 
thanks.
would you be able to stuff a meter across the blob and check it for me?
i would really like to know if its a diode or a resister, and if its a diode, in series i would really like to know if its a "good" one with small voltage drop.

so if its ESD protection, then it could be just "external" vrses "internal" and could be basically the same thing in other emitters, just visable, and on the star instead of the emitter?


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## evan9162 (Oct 30, 2007)

VidPro said:


> thanks.
> would you be able to stuff a meter across the blob and check it for me?
> i would really like to know if its a diode or a resister, and if its a diode, in series i would really like to know if its a "good" one with small voltage drop.
> 
> so if its ESD protection, then it could be just "external" vrses "internal" and could be basically the same thing in other emitters, just visable, and on the star instead of the emitter?




It's definitely a diode. It has a turn-on voltage around 1.1V. It's in parallel with the whole LED array (so doesn't add to the Vf of the LED). It looks like it may be more for reverse voltage protection than anything. It could be a zener, but there's no way to test it to find out Vz without removing it from the board. 

The anode is connected to the - power pad, and the cathode to the + power pad, so it's only forward biased when you connect power backwards to the Atlas. The problem with this arrangement is that if you use a low voltage power source to find the proper polarity (which is pretty safe to do for many LEDs), and wire it backwards, it will forward bias the protection LED, pumping several amps through it. If it gets destroyed, then you would be putting the full reverse voltage of your power supply across the LED array, which could damage it.

I think if you end up damaging/destroying the protection diode, you can just remove it all together, and it won't affect the functionality of the LEDs at all. But you may lose some transient or ESD protection as a result.

In short, the Atlas does not take reverse voltage well AT ALL. Even a small amount could destroy the protection diode. Definitely pay attention to the power pad markings if you decide to use one of these.


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## VidPro (Oct 31, 2007)

thanks Evan.


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## chimo (Oct 31, 2007)

Very nice write up. Thanks!


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## James Jackson (Nov 1, 2007)

Evan,

Thanks for the writeup on the Lamina Ceramics LED.

I reluctantly decided last year - or early this year - to abandon Lamina Ceramics as a potential supplier of LEDs - as it seems that almost every LED that they introduced early-on is now discontinued.

I'm not sure about current status of the BL-4000, but the BL-1000, BL-2000, and BL-3000 are (if I'm not mistaken) obsolete - and no longer in production.

I purchased several of the BL-2000's (I believe this was the ones), and put them through testing... and was impressed. But - when I went to order them again... Mouser no longer carried them, and Lamina Ceramic's web site had them flagged as discontinued. (I felt like I had had the rug pulled out from under me.)

Very frustrating.

Thanks again for the report. Personally, it wouldn't matter to me if you gave an extremely glowing report on this LED - I wouldn't use it just because it is from Lamina Ceramics.

Regards,

James Jackson
Oztronics


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