Future development of the maximum luminance of LEDs

Flashlight Modding and DIY Parts
108

Ok so I found out two things:

1) The KW CSLNM1.TG (image A) has a smaller lm and cd value than the KW CELNM1.TG (Image B) simply because the datasheet has a larger bin range for the second one. The website then lists the average lumens and candela as the (min+max) / 2 making it seem like the CELNM is better.

image A, CSLNM)

image B, CELNM)

Even though the CELNM may have a higher bin, we likely will never have a chance to purchase those anyway, so effectively it is the same as the CSLNM.



2) Also, as expected, you can see in the datasheet that the smaller thermal pad does hinder the overdriving ability, as the curve only shows 1.7x output at 2 amps, where the CSLNM has 1.75x output.
For this reason, the CSLNM is a much better choice because not only does it perform the same, assuming you get the same bin, but it has the same thermal pad as the black flat allowing it to be used on XP-size boards and gets better overcurrent ability than the CELNM.



As for the performance compared to the black flat, lower thermal resistance only seems to make it maybe 0.05x higher output at 1.5A when compared to 1A according to the flux-current graph. The main benefit will be not having the notch in the corner.

Despite smaller contact pad size, the CSLPM1.TG (seen below left) has almost the same thermal resistance as the Q8WP and gives it the same overcurrent capability according to the datasheet graphs.

The benefit will be that it can now fit on an XP-size board easily just like the black flat.
It is unclear how having the new only-surface-emitting design will affect the intensity, it has no weird polar distribution from side LES like the Q8WP does, The die area is 0.08mm^2 larger, and the flux for the minimum bin is 400 now instead of 355.
With similar or more lumens, and no side LES, but larger die area, I would expect similar cd/mm^2 than the Q8WP, which is already extremely high 245cd/mm^2.

The specs from the website (in this post) show the Q8WP as higher flux because the highest bin goes up to 710lm while the new LED only goes to 630.
But since we seem to never get the highest bin anyway when buying our LEDs this likely does not matter as much as the minimum bin does.

Based on this, there are two LEDs which are important to test as soon as they are available to buy:
OSRAM OSTAR® Projection Compact, KW CSLNM1.TG
OSRAM OSTAR® Projection Compact, KW CSLPM1.TG

109

Very interesting, thanks for the heads-up! These looks like a very nice, practical upgrade! The bigger die of the KW CSLPM1.TG could allow for higher max lumens. The central solder pad is smaller though compared to the Q8WP, but the thermal resistance is actually the same.

110

Yup!
I would guess the CSLPM will get similar intensity to the “new black flat” CSLNM and just more lumens.
The insulated center pad and no cut corner makes these LEDs really appealing, even if they don’t perform much better than the current ~250cd/mm^2 LEDs.
But of course I do hope that they perform a bit better.
I can’t wait for them to be available :slight_smile:

111

It would be interesting to test Stanley HCNW115AJTE

  • 0.96 mm²(unclear, up to 1 mm²) (Blackie: 1.122)
  • 265-410 lm at 1A*3.25V (Blackie: 250-400 at 1A*3.05V)
  • 3 K/W (Blackie: 4.3)
  • 2.096 mm² thermal pad (Blackie: 2.67)

If top bins are orderable, that could be a win.

112

Interesting, the package does look a bit weird though!
One difference: the Stanley has two bond wires.

113

Luminus now has a new LED on the site, the XP-G2 sized brother of the SST-40, the SST-20 (datasheet).

Features:

  • Thermal resistance: 3.5°C/W (XP-G2: 4°C/W, CSLPM1.TG: 2.6°C/W)
  • two different solder profiles:
  • => A120: XP solder profile with neutral center solder pad
  • => B120: smaller Osram (Black Flat, Square etc.) solder profile with neutral center solder pad
  • rated up to 3A
  • square die (not retangular)
  • brightness at 1.5A: up to 10.7% higher compared to XP-G2 S4, average might be closer to S3

Maybe 220-230cd/mm^2 are possible? Benefits here are that the new Luminus LEDs seem to be chaeap and easy to obtain. They also seem to still have a cool-white tint after de-doming.

114

Love those bond wires… :person_facepalming:

115

I wouldn’t worry about those right now. The SST-40 goes up to 9A and also had just two. It’s possible that they use the same ones in this LED.

116

And, though not the scope of this thread, the SST-20 comes with some warm 95 CRI versions.

117

Not too concerned with current capabilities, those long bond wires make it very hard for a clean de-dome. They tend to break when the dome releases during the chemical de-doming process. I went thru over 30 SST-40’s. Vinh gave up on them too, he just shaves them now.

118

I wish a purely chemical dedome would be easier with these, but I’m not holding my breath. I’ve had good luck with a combination of shaving / slicing / chemical dedome. Considerably more work, but still good results.


click for larger image

119

SST-20 L2 6500K is available on kaidomain for $3.19.

120

prophotonix never answered.

I found 2 more companies which may be willing to make a batch of custom LEDs:

At least the latter has the necessary expertise:

I haven’t mailed them, if one wants to do it - just do it.

121

What is the die size of old XP-G2?
Here I see 2.16 mm².
In the CRX thread 1.66 mm² for old and 2.18 mm² for new…

200 cd/mm² seems semi-consistent with the smaller number.

122

1.66mm^2 for the first version from 2012-2014

123

Then koef3 got about 216 cd/mm²

124

One thing to note here is that the way of measuring the die size is not perfectly accurate. It is usually done by carefully taking a picture and then counting pixels.

125

What about this LED (don’t know if this LED is already discussed)?
http://www.nichia.co.jp/en/product/led_product_data.html?type='NJ2W270A-Y7'

126

I noticed it a few months ago, but didn’t see any big benefits. The rectangular shape of the die is definitely a downside.

They do state the luminance!

Die size: 0.93mm^2
Real thermal resistance: typ 4.1cd/mm^2
Luminance at 700mA: avg 110cd/mm^2

Edit:
The Black Flat is 20% larger, but only does 66cd/mm^2 at 700mA. So the Nichia might actually be really good if one can live with the die shape! Thanks Schoki!

Edit2:
The weird thing is that it’s a 6V LED! This makes it easier to drive the LED to its max in single cell lights, there are good boost drivers available.

I wonder how far apart the two dies are. This could ruin the beam with smo reflectors.

127

OK, so let’s consider the dies separately, so we can compare with Blackie a bit better.
Half-Nichia:
.465 mm² die. 110 cd / mm² at 1.5 A/mm² and 5 W/mm².
Blackie:
1.122 mm² die. 110 cd / mm² at 1.25 A/mm² and 3.85 W/mm².

Nichia has a bit better thermal resistance, but it doesn’t seem to be enough.
Also, its LES is significantly higher than die size in case of Nichia.
So probably not too good….