Cree has announced the XLamp MK-R packaged LED that integrates four die and, at 7×7 mm, fits between the 5×5-mm XM-L family and the 9×9-mm MT-G family. The new MK-R LEDs deliver as much as 1600 lm at 15W in a 5000K CCT – matching the light output of many larger chip-on-board (COB) LED arrays for solid-state lighting (SSL) retrofit lamps and luminaires.
"The light output is more in line with what you see from a COB array," said Cree product marketing manager Paul Scheidt. He added that the small – relative to COB arrays – 6.5×6.5-mm optical source delivers a tighter beam angle. The smaller source makes it simpler to add optics to deliver the tight beam needed for directional applications.
In terms of efficacy, Cree is touting the MK-R for reaching the 200 lm/W level. Cree says that the product is the follow-on commercial product to the laboratory 200-lm/W efficacy achievement announced in February of 2010.
"It’s amazing that Cree is able to achieve a 200 lm/W LED so quickly," said Nicola Vendrame, CEO of Linea Light group. "The high efficacy of the MK-R LED means that we can drive the LED harder for more light output without creating heat issues."
Typical operating conditions
Realistically, however, the LEDs will be applied at much lower efficacy levels due to higher drive current and in many instances warmer CCTs. For example, at 3000K CCT, 80 CRI, 700-mA drive current, and 85°C junction temperature, the MK-R delivers 865 lm at 106 lm/W. And many designs may drive the LEDs even harder.
Cree offered some theoretical specs of retrofit lamps calculated based on the MK-R specs. The LED could enable an 18W PAR38 delivering 1215 lm with 3400 cd in center beam candle power (CBCP) – essentially a 90W Energy Star halogen equivalent. The system efficacy for such as design would be 68 lm/W.
Just last week, Cree had announced the 5×5-mm single-die XM-L2 LED family that also targets directional applications. In our article on that LED we covered a theoretical 5W MR16 SSL design that could deliver 369 lm with 7800-cd CBCP and a 9° beam pattern. Cree says that the MK-R will enable a 6W MR16 lamp with 535 lm output, albeit at a lesser 1500-cd CBCP. The difference comes in the wider beam from the larger optical source in the MK-R LED. The 6W MR16 would be the equivalent of a 35W Energy Star halogen lamp, according to Cree.
Cree continues to broaden its product line with LEDs that are increasingly application specific – an industry trend we noted in our feature on packaged LEDs early this year. The MK-R is also another LED that is based on what Cree calls SC3 (SC cubed) – its third-generation silicon-carbide-based manufacturing platform.
"The MK-R LED is another game changer for the industry," said John Edmond, Cree co-founder and director of advanced optoelectronics. "An LED with this level of performance can accelerate the development of high output lighting applications and could enable applications we haven’t even thought of yet." Linea Light's Vendrame added, "The MK-R LED has the right combination of size, color consistency and optical control to enable the next generation of performance in our indoor directional luminaires."