LED test / review

EN

Cree XLamp XHP35 High Intensity

XHP35A-H1-0000-0D0BC40E3
XHP35 HI flux E2, ‚tint 3C‘

UPDATE --- 06/23/18 --- raw data added (link)

Since the XHP35 is available on the market, it is often used in high power flashlights. With this LED many flashlight manufacturers got more output at same size and battery configuration. In all the time, I didn’t test this LED though.

In this review I test one of the highest bin availabe XHP35 High Intensity (HI) to date, and – as comparison – a slight less efficient XHP35 HI in C4 bin. I got the XHP35 HI with stated E2 binning a few months ago from a TLF member, the C4 one from mouser.

Technical data

Tsp 85°C / If 350 mA

Order code: XHP35A-H1-0000-0D0BC40E3, of E2 variant not available

Type: quad die (Flip Chip / Lateral)
Binning: E2 min. 590 lm (C4: 475 lm)
Rated voltage: typ. 11.3 V (max. 11.9 V)
Max. forward current: 1,050 mA
Viewing angle: typ. 115°
Thermal resistance: typ. 1.8 °C/W
Junction temp.: 150 °C

Official datasheet is available here (Cree website, pdf)

Appearance and LED die

The XHP35 is the smallest LED of the XHP (eXtreme High Power)series. With 3.45 x 3.45 mm the XHP35 HI has the same size like other XP LEDs and also uses the well known standard XP footprint.

Two bonding wires are visible, and four single dies can be discerned even without power the emitter up. Two of them are not connected via bonding wires, so the electrical connection lays underneath them (Flip Chip technology).

Because of this design the LED runs only on 12 Volts - the dies are connected in 4S (4 in serial).

Because the silicon dome is missing, the emitter is very flat. All Cree LEDs without a dome except the new XD16 are labeled as ‚High Intensity‘ (HI). There is also a High Density (HD) version available, which is fitted with a dome.

The footprint reveals no surprises, here shown in used condition.

Like in unpowered state the four single dies are visible. Unless the other XHP 1st gen LEDs, there is no gap between them. This should improve the beam pattern even in SMO reflectors.

The Light emitting surface (LES) of the XHP35 High Intensity is 5.32 mm² (0.00825 sq in) in size.

Power and overcurrent capabilities

25 °C Tsp, unless noted otherwise.

raw data here

Within official parameters

• At 1,050 mA (max  rated current): 1,537.2  lm @ 13.06 V (C4 bin: 1,355.6 lm @ 13.20 V)
• Power at rated maximum: 13.71 W (C4 bin: 13.86 W)
• Efficiency at 1,050 mA: 112.1 lm/W (C4 bin: 97.8 W)
• At 350 mA (binning current, but 25 °C Tsp): 633.1  lm @ 11.96 V (C4 bin: 558.0 lm @ 12.13 V)
• At 350 mA (binning current, corrected to 85 °C Tsp acc. To Cree datasheet & PCT): 562.2 lm (C4 bin: 495.6 lm)

Overcurrent:

• Maximum at 3,200 mA, 2,851.2 lm @ 15.29 V (C4 bin: 2,495.9 lm @ 15.37 V)
• Power at maximum 48.9 W (C4 bin: 49.2 W)
• Sweet spot at 2,200 mA (2,545.5 lm @ 14.29 V, C4: 2,239.7 lm @ 14.38 V)
• Power at sweet spot 31.4 W
• Bin E2: Efficiency at max 60.2 lm/W, in sweet spot 81.1 lm/W

Interesting facts

• The XHP35 HI stated as E2 is more efficient than the E2 one, at avg. 12 %.
• The E2 LED apparently has a slightly better heat dissipation, the max. current is 200 mA higher
• At 85 °C the light flux of E2 matches pretty much exactly that of the XHP35 HI C4 at 25 °C
• The E2 bin for XHP35 HI is not listed at the Cree PCT. If you would compare the HI E2 with other LED you had to choose the XHP35 HD variant from their list.
• In overcurrent condition the Vf is very high, about 15 V.

Now a few words to the stated flux bin of this LEDs.

The min. light flux for E2 bin is 590 lm @ 350 mA 85 °C Tj. See also Cree PCT for this.

The XHP35 HI E2 tested here delivers 562.2 lm where the C4 delivers 495.6 lm.

Conclusion: the first LED does not reach it’s minimum light flux for bin E2, the C4 binned LED on the other hand is slightly better than stated in datasheet (min. 475 lm @ 350 mA 85°C Tj). So the alleged E2 flux bin is in fact equivalent to D4 bin (min. 550 lm) – the highest XHP35 HI bin which Cree list in his official documents.

Against my experiences, the spread in efficiency is obviously very big. A XHP35 HI E2 I tested much earlier but with the same test setup reaches almost 3,000 Lumens and therefore complies with the stated bin.

The apparently existing of such high bins of Cree emitters makes me suspicious (pictures of Cree reels with XHP35 HI E2 printed circulates even in the BLF). Not only in case of this LEDs such high light flux bins are not listed in official datasheets and the Cree PCT. But why Cree makes such a secret out of LED binnings, and why Cree doesn’t sell this LEDs officially (like at Mouser or something)?

I have a possible theory about this. Maybe the stated highest flux bins are not really binnings, but ‚golden samples‘ which are detected and sorted out at production while sorting each emitter in bin and color kit. Unfortunately the amount of these super-efficient emitters could be much too low – and if such LEDs are offered at the market officially the availability simply could not be guaranteed. This could maybe explain why some of the tested XHP35 HI E2 have a unusually large spread in efficiency.

Maybe some of you members have a better theory about this? The maybe existing spread in the bins and max. light flux could be very interesting for our thrower and ‚maximum possible performance‘ fans.

Luminance

I established a new method for determining luminance, especially to ensure more realistic values for 'real-life' conditions (flashlight use). The measurements are taken with a new original Convoy C8 reflector, but with same heatsink / setup as previously used in flux measurement.

Reflectivity for reflector 85 %

Transmission UCL glass 97,8 %

Values at 25 °C Tsp, for 85 °C Tsp values are 6 to 14 percent lower, depending on LED

LEDs marked with Warning sign uses old values are still taken with previous method (determining die size) due to problematic light distribution (donut holes etc).

Important: due to destroying of the emitter used in the light flux I had to use another XHP35 HI E2, which might be more efficient than other samples (see also 'interesting facts' section above). Selecting of very good samples might be necessary for highest-performance mod projects.

With 171 cd/mm² the luminance of the XHP35 HI in E2 binning is very high. It is as high as of the XP-L HI V3 and comes close to the dedomed SST-40-W!

At approx 35 percent bigger LES as of XP-L HI V3 the light flux of the XHP35 HI E2 used for luminance test is also approx 35 percent higher, so the values are plausible. The C4 one performs much lower, but comes still close the dedomed XP-G3 in highest bin.

Light quality and use in optics

At this point I don’t need to explain further. The XHP35 HI is often used in modern flashlights and their beamshots are published everywhere on the net.

Because of the missing gaps between the single dies there is no big ‚black hole‘ in the center of the spot. At some flashlights there might be some yellow or red areas in the spot (see beamshot) or little dark points, but much better than the weird beam patterns of the bigger XHP50 and 70.

In the luminance test with a Convoy C8 SMO reflector there were no darker spots or miscolored areas in the beam.

To mix the light and get a really nice and uniform color distribution I recommend the use of an OP reflector and/or diffuser film.

Conclusion

A good LED, like everyone know. Relatively nice beam pattern, also a acceptable performance and good handling makes it to a good choice for modding lights. But – there is one big con: the XHP35 HI needs 12 V and also special electronics. Because of this the XHP35 is not suitable for all flashlights despite the same XP footprint.

The flux bin E2 is not reached in this test, it rather corresponds to D4.

Pro

• very high performance for it’s size
• very high luminance, even higher as XP-L HI V3 (E2 binning only)
• industry-standard XP footprint
• Good light quality and beam pattern if used in flashlight optics

Con

• 12 V variant only, special electronics needed
• very huge performance / efficiency spread in E2 labeled samples
• E2 flux bin not reached at sample used in light flux test (D4)

I hope you enjoyed this test - and thanks for reading!

Greetings, koef3