Luminus SST-40, a N4 BA bin tested

Spec sheet here: https://www.mouser.com/datasheet/2/245/Luminus_SST-40-W_Datasheet-1499204.pdf

says one 70 CRI on page 7 - "WCS", where S is for standard 70 CRI. Least this is today of what we know. The SST-20's fill the high CRI niche for now.

Basically high CRI means lower output - that's how it seems to be working now. What's new in the last couple years is we can get NW tints in high output bins, but the high CRI kills the output.

Going to re-post this to this thread as a reference since I took the time to do it. This is two unverified bin SST40’s in two different lights (D80 and Enogear EC21, basically Nightwatch NS22). Both were sold to me as 6500K which I suspect is accurate.

I did this to clarify to myself and others what to expect with a slice vs dome on LED and to predict what an SST40 5000K might do with dome on/off, assuming it behaves similarly.

Here are measurements from two different reflector lights and LED sources taken at the hot spot:

And the wider spill:

In my opinion the 6500K+ with dome on makes my eyes go :confounded: if I look at the spill. It’s awful and basically unusable. The hotspot is generally very intense and far away so it matters slightly less and is probably passable if you need the output.

After slicing, the shift is still noticeable but much better in the spill. The spill becomes more faint so the shift is less bothersome and the hotspot is so intense its hard to notice much difference there.

TL;DR de-dome these at high output or use another LED. The 5000K will probably be better but still have huge shifts. Probably no need to worry about it going too “warm” after dedome. Seems unlikely at any decent current.

I wonder where did Astrolux get the NW sst-40

they do not look like real SST-40s
bond wire pads are different
also the dots are not in square pattern
Die seems to be a tiny bit smaller
Phosphor edge is different, also phosphor itself looks different

That looks at least interesting, if it is not a real SST-40 then at least the forger did its best to make it look like one, if it is a real one then Luminus made a new die for it.

as it seems Astrolux can not source any more 5000K LEDs my thought is it may a very old die, different from any now sold ones

So I tried a N5 BC (Voltage: VH) in my M21A. My LD-A4 driver in the light was ordered with 8-12 Amp range so I set it to the bare minimum. Tail current was measured at 7.94A and voltage across the LED at 3.446V. It’s obviously bright AF, quite close to the sliced dome 3V XHP50.2 that it replaced.

The XHP50.2 measured 3.226V across the LED and the MOSFET probably took a hammering and caused the driver to overheat the whole time.

I will have to replace the LD-A4 with a LD-B4 driver and the corresponding PCB to combat the hot MOSFET. But I need some advice…….
Will it be OK to run the SST-40 at 8A? Or should I dial it down to 7A? The light is being used as a tactical light with high to low modes, no mode memory. So it always starts in turbo.

8A is about perfect.

I’d also put a copper shim on the MOSFET to help it with overheating.

Where can I buy a copper spacer? I have silicone cubes and sheets that I can use to space it. Otherwise I’ll have to make my own… The MOSFET is definitely running cooler with higher Vf of SST-40, but more cooling will definitely help. It’s a pity my 7-9 Amp LD-B4 failed for some unknown reason.

Oh, you just take a copper sheet, and cut a rectangle the size of the MOSFET over it.

Wow… Do I just tape it to the MOSFET?? Sounds risky. I thought about using 1mm silicone sheets on the driver side of a thick circular copper disk and insert silicone cubes on the shelf side to add some pressure as the driver is pressed down by the retaining ring.

Well, don’t you have some thermal adhesive on hand?

That’s how to do it.

Otherwise, you can risk a short.

Yeah I have some… I will then fill the cavity between the shelf and driver with silicone cubes to add pressure and that little bit extra heat conductivity.

Thanks for the advice.

if you really mod on it switch to a better MOSFET, those mosfets are designed to get heat lost to the PCB side, adding copper on the top wont help

with SIR404 or Infineon with 1.2-2.5mOhm there is at 8A no considerable heat present, those can go up easily to 25-30A
2mOhm*8*8A—>0.128W heat

look into the Emisar D18 for example where the FET is quite stressed
1.25mOhm*35*35A—>1.53W

with a considerably good PCB design preferrred 2OZ copper and thermal viases 1-2W heat are OK

Mosfet resistance is irrelevant in case when linear driver operates in linear mode, in that case power dissipation in mosfet is (V_batt - V_led)*I_led.

So switching to other mosfet won't change a thing. Improving thermal path between mosfet top side and pill does help a lot, but it's not easy to make very good thermal path for deep pills/driver cavities. Example how to do it is S2+ thermal kit:

https://led4power.com/product/ld-a4-thermal-enhancement-kit-convoy-s2/

But again, this is not simple for many flashlights and cost is high, if LD-B4 can be used, it's the best method.

Your calculations are valid only when mosfet is in saturation mode - direct drive, where I^2*R loss it the only cause of heat generation.

Interesting results. I always thought dedoming this shifts the DUV higher which is the opposite of what you got. I wonder why the dedomed SST-40 NW in the Nightwatch NI40 is so horribly green +0.02x.

I might slice my FT03 SST-40 NW since there are now replacement LEDs available. I’ve never attempted a complete de-dome though and dont really want to get into doing that myself.

Have any one successfully dedomed SST40, Not slicing, i want to dedome it because i got a very cool white sst40 and i want it to shift color plus the throw

I just got 10 more SST-40 from KaiDomain. Do you want me to try one for you? What methods of de-dome do you have at your disposal? I would want to do what you could replicate, or it wouldn’t be much use to you. :innocent:

EDIT: Actually, just realized, I have some dead ones I burnt up. I’ll try those first! :smiley:

AFAIK Maxtoch seems to be the only one reliably chemically dedoming these. Seems it wasn’t easy when others tried?

Do you have any idea what chemical they might have used?