LED test / review EN Cree XLamp XHP70.2 P2 40E, XHP70B-01-0000-0D0BP240E Firstly, a note: After writing so many German LED test reports, this is now my first one also written in English. Because English is not my native language, there could be some smaller (or bigger?) mistakes in the text. Despite that, I hope this report is helpful for all of those who want to build some lights with this big LED. Technical data of the emitter tested here Tj 85 °C, If 2100 mA (6V) Order code: XHP70B-01-0000-0D0BP240E Nomenclature from manufacturer: XHP70.2 Type: quad die Binning: P2 (typ. 1,830 lm) Forward voltage: typ. 5.6 V, max. 6.1 V (12 V: typ. 11.2 V, max. 12.2 V) max. Strom: 4,800 mA (12 V: 2,400 mA) rated CCT: typ. 4,000 K (color kit 5-Step 40E) Viewing angle: typ. 120 ° Thermal resistance (junction to solder point): typ. 0.9 °C/W LED junction temp.: max. 150 °C I purchased the emitter from Mouser. Unfortunately, the first sample was not working properly – the nominal light flux at binning conditions was at least ≈ 20 percent lower than stated in the datasheet. In addition to this some of the dies already lit up at 3.2 Volts, despite missing overcurrent. But Mouser reacted in a professional way and after a short conversation they send me a replacement, which I used for this test. First appearance Like all new generation Cree LEDs the XHP70.2 appears yellow in color. The whole visible die including the outer surfaces is covered with phosphor; the external dimensions are 7.00 x 7.00 mm (0.276 x 0.276 in). The footprint is the same as that of the predecessor so the whole range of accessories for old XHP footprint should also be compatible for this new LED. This allows lower development costs when updating products. On the pictures the four dies can be easily discerned. Because of the symmetric shape of this LED it's possible to use lathe spun components for spacers or insulation gaskets. Like the XHP70 the needed voltage can be set via the LED PCBs electrical layout. All available XHP70 and 70.2 are suitable for 6 or 12 V forward voltage. If the middle contact on the LED (thermal pad) is isolated from anode/cathode electrically, the LED runs on 6 V config (2S2P). Otherwise, if the thermal pad is connected with anode/cathode, the LED runs on 12 V config (4S4P), which halves the needed current. Also see this image (Cree). Light emitting surface The visible light emitting surface area is bigger than that of the XHP70 – but the gaps between the four dies are noticeably smaller, too. Because of that, the surface brightness density should be lower despite the higher possible lumen output. Typical for the new Cree LEDs is the blue-yellow-dotted phosphor layer on the surface, and the yellow layer around the dies. The gaps between the single dies are small and also covered with phosphor. Because of this they emit too light. The total light emitting surface (LES) area of the XHP70.2 is 31.52 mm² (0.0489 sq in) in size. The four single dies are 7.88 mm² (0.0122 sq in) each. Power and Overcurrent I compared this LED with other popular emitters, like XHP50.2/70 and MT-G2. (Click on the diagrams for larger images!) Within official parameters: at 4,800 mA (max. forward current in 6 V config): 3,810 lm @ 6.09 V power at rated maximum: 29.2 W efficiency at 4,800 mA: 130.5 lm/W at 2,100 mA (Binning conditions, 25 °C Tsp): 1,876 lm @ 5.73 V – calculated at 85 °C acc. to datasheet and Cree PCT: 1,705 lm - N4 The emitter tested does not reach the binning specified from Cree (1,830 lm @ 85 °C/2,100 mA). It’s not P2, but N4 (1,710 lm). I measured a lot of emitters (around 30) in my test setup. Most of all light flux results (also calculated to 85 °C Tsp) are equal to specified binnings, sometimes lower, sometimes higher. A XHP50.2 tested and shown in the diagram corresponds to the binning specified by Cree (J4). Currently I cannot measure the luminous flux at 85 °C directly. So I had to calculate the flux for hot binning (85 °C) acc. to the specs in the datasheet. From 25 °C the decrease to 85 °C in luminous flux is around 12,5 percent. Overcurrent: 20 Amps lab power supply maxed out! possible light flux maximum not reached at 20 A, 9,228 lm @ 7.29 V at 20 Amps power at maximum 145.8 W Sweet Spot at 15 A (8,379 lm @ 6.95 V) power at sweet spot 104.3 W efficiency at maximum 63.3 lm/W efficiency in sweet spot 80.3 lm/W I define the sweet spot as the position in diagram which gives a good average between light flux, current and efficiency. The maximum should be reached at 21 to 24 amps, at approx. 9,300 to 9,500 lumens. LED will be consuming 170 watts! The XHP70.2 performs much better than all other tested LEDs here. The overcurrent capabilities are better and the light flux maximum is at over 20 amps – the maximum range of my power supply. Moreover, the Vf is a lot lower than that of the other emitters. The XHP50.2 is more efficient than the MT-G2 and reaches the same light flux maximum, but at lower current. This is a clear sign that the MT-G2 is outdated and shouldn’t be used in new designs anymore. (maybe if superior color consistency without artifacts in light pattern is required.) The XHP50.2 used in this diagram is measured with bin J4. This is a sign that the XHP70.2 actually emits less total flux than stated in the datasheet for this bin. Luminance The measurements here were done in a totally dark environment, with no reflections on the lux meter. Caution: Because of the lower light flux/binning of this emitter the measurements aren’t fully consistent to XHP70.2 to the P2 bin. LEDcurrent If mAluminance cd/mm2Cree MT-G2 Q0 2,800 19.6 8,600 45.2 16,200 (max) 58.1XHP70 N2 2,800 24.8 8,600 59.8 14,800 (max) 79.3XHP70.2 P2 2,800 22.9 8,600 56.9 20,000 93.3XHP50.2 2,800 45 8,600 100.3 13,800 (max) 121.1XHP35 HI E22,800 (max) 151.4 The surface brightness of the XHP70.2 is higher than that of the XHP70, but it profits only from the higher maximum current and the higher luminous flux, resulting from this. At lower currents the XHP70 performs a bit better, simply because of the smaller light emitting surface. The XHP50.2 and XHP35 perform a lot better and deliver a substantially higher luminance due to high power denstiy (XHP50.2) and dome-less construction (XHP35 HI). Just for comparison: the SYNIOS DMLN31.SG tested here delivers 297.8 cd/mm², the Osram Oslon Black Flat 266.5 and the good old XP-G2 S4 2B 197.3 cd/mm². Light quality and use in optics The newest generation Cree LEDs (XP-G3/L2, XHPxx.2) are similar to each other. The all create a yellow-tinted corona around the spot when it's used in conjunction with reflectors and clear lenses. With this LED it’s the same. To show you this problem in a more practical manner I put the tested emitter in a flashlight which is normally used with a XHP70. It delivers round about 2800 lumens with one 26650 and is equipped with a OP reflector, what should improve the light pattern. The yellow-colored corona is visible and annoying. The spot is definitely cooler than the stated 4000 K CCT - I estimate the color temperature is higher than 4500 K. The specified color temperature can only be reached in cb (ceiling bounce) situations or in optics which mix the light, like diffusors or TIR optics. In a flashlight this doesn’t happen in most cases. But not everything concerning light quality is bad. Because of the missing “gaps” between the single dies, the known “cross” in the spot is in case of using reflectors or lenses totally eliminated and not visible anymore. This problem, known from many standard flashlights, has largely been solved through usage of special/modified reflectors or diffused/matte lenses. Summary The XHP70.2 is a noticeable leap in performance and overcurrent capabilities. With 9228 lumens and 146 watts makes this one of the brightest power LED available today. The light emitting surface is bigger than of the XHP70, in addition to this the beam pattern not only on the whitewall isn’t so good at all. The yellow rings/areas around the spot known from other Cree LEDs like XP-L2 or XP-G3 exists here too. On the other hand, the „cross” known from it’s predecessor XHP70 is not visible anymore. When high luminous flux is the highes priority and the light quality (if used with optics) can be neglected, this LED is currently the best choice! Pros: - ultra high luminous flux! - very high over current capabilities - very low Vf - high efficacy especially at high current - low thermal resistance Cons: - imperfect color consistency when used in clear optics (yellow) - rated CCT can only achieved with mixing the light - emitter tested here has lower luminous flux at binning conditions than stated in datasheet/order code Thanks a lot for reading! Regards, Dominik Mistakes and suggestions are best sent via pm.