LED test: LatticeBright XD-3535 (from an SK68 clone)

Flashlight Modding and DIY Parts
1

These LatticeBrights are everywhere in cheap Chinese knockoffs. This one is a 3.45mm package Cree XPE clone from a $3 SK68 clone I got from GearBest in 2015.

Here’s a datasheet for the LatticeBright XD-3535: http://www.latticebright.com/UploadFiles/Document/201705/18080550319626505.pdf

I of course can’t be for sure this emitter is that exact model, but the specs seem to somewhat correspond to my measurements.

Manufacturer’s specs
Forward voltage: 2.8-3.2V at 350mA
Maximum current: 700mA
Luminous flux: 110-165 lumens, 150 lm typical at 350mA at 25°C
Color temp: 5000-8000K, 6500K typical
CRI: Ra 70
LED package size: 3.45 x 3.45 mm

Going by the datasheet mine would be the lowest Q5 output bin (107-114 lm @ 350mA).

Test was done on an Al heatsink. MCPCB was put on top of a graphite thermal pad and clamped securely down with two screws. Tests were done in an integrating sphere.

Maximum output of 322 lumens is reached at 2.2A (3.18V, 7.0W)

Efficacy is passable at low currents but falls under 100 lm/W above 500mA.

Please note that the TM-30 numbers in the table above are from TM-30 version 15. CRI data later is version 18, which generally gives a bit higher numbers.

Color temperature is higher than specified and tint goes out of whack pretty fast when more current is applied. These should probably be only run at a couple hundred mA at most. LatticeBright specs them at 700mA max.

CRI Data

At low currents CRI is better than expected at Ra 76 and TM-30-18 Rf 74. It even reaches Ra 80 above 2A. This of course doesn’t really matter as the color temperature is horribly high at any current starting at 7000K on 100mA and reaching 9000K at 1400mA.

At 300mA

At various currents
100mA
500mA
1A
2A
2.5A

2

Thanks for the data.
It has been some some ago since I last used an XP-E2 in a flashlight build, so many nice(r ) leds to choose from nowadays. But if I do use them again I will remember not to go for a Latticebright by accident :slight_smile:

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As far as I know, LB don’t usually make NW or WW leds. Their usual CCT range starts at 5000k all the way to 10000k.

So, if you got 4000k or warmer tint then you’re pretty safe from LB. Unless some dude actually went up to LB (or some other companies that do make these clones) and ask them to do a custom made CCT.

4

Well, you are actually the only dude I know that does such things :wink:

5

According to that datasheet I linked there should be a warm white version too

6

Ohh wait, I took that back.

Now the question becomes whether the warm white version has been spotted in the wild.