Lumileds’ LUXEON C ES enables small, high-output, complex, multi-color arrays

Multi-color LED fixtures based on a large LED cluster under a single optical system are preferred in many situations for their ability to deliver highly accurate illumination with superior beam quality. Until now, however, LED design has not allowed engineers to address the conflicting needs and challenges inherent to close-packed, high-power LEDs. These challenges include maximizing light output, reducing array size, excellent color mixing, delivering efficiency, complex electrical routing, and thermal management. To properly address such issues, Lumileds LLC of San Jose, CA, USA determined that the best approach was to develop the new LUXEON C ES, available now through Lumileds’ global distributor network.

“Through our discovery process we determined that the best results would come from a large die in a small package with a dome would yield the best, scalable result,” says Benjamin Khoo, Lumiled’ color LED product manager. “Key limiting factors to creating a scalable array solution included LED-to-LED spacing and package edge to die edge clearance. Lumileds engineers successfully addressed both with the new LUXEON C ES.”

A video review of Lumileds investigation and conclusions regarding large, complex color arrays has been published by the LED Professional Symposium.

As part of the design investigation, Lumileds engineers investigated optimal LED arrangement and electrical footprint. They determined that a ‘random’ arrangement of the LEDs provides optimal color mixing. Using multiple colors of course requires complex routing of electrical traces, which also needed to be managed, preferably, on a single layer of copper. The 3-stripe footprint proved to be an exceptional fit for this, especially given the very limited space between LEDs.

Extended analysis proved that high driver current and maximum thermal dissipation could be achieved through the design and the use of an isolated thermal pad with copper pedestal PCBs. In this scenario, LUXEON C ES can be driven at current of >2A for maximum output while achieving the necessary thermal management.

Optically, Lumileds’ engineers determined that the use of a dome (rather than undomed) was optimal, and that light output could be increased by as much as 40% and flux per thermal Watt could increase by as much as 60%.