LED Record Efficacy and Brightness
Designed for general lighting applications such as street, industrial, and parking garage lighting, the Cree XLamp® power LED sets new records for LED brightness and efficacy, up to 85 lm/W at 350 mA. The XLamp utilizes Cree's performance breakthrough EZBright™ LED chip; both products include technology that was developed in part with R&D funding support from DOE.
Cree's achievement builds on initial research conducted under a three-year DOE R&D project. The objective was to demonstrate that white LED technology could be successfully scaled up (in terms of electrical input/optical output power) to levels suitable for general illumination applications, with superior energy efficiency. The project required significant improvements in such diverse areas as chip efficiency, optical design, and thermal management.
XLamp Performance Builds on Blue LED Breakthrough
The white LED is composed of an InGaN-based blue LED chip and a down-conversion phosphor. The performance of the white LED depends on the quality of the blue LED light engine. The new style EZBright1000 power chip, which provides higher light output and efficiency than Cree's previous power LED chips, includes several advances in device design that improve the light extraction and current injection aspects of the device. Some of these design elements were first investigated and demonstrated with DOE R&D support.
Additional internally-funded R&D efforts enabled Cree to subsequently develop a manufacturable version of the improved LED chip architecture. This work ultimately resulted in a brightness increase of 25 to 30% and a demonstration of packaged blue LEDs with external quantum efficiency of up to 50% at 350 mA drive current. The improved voltage performance of this chip design also improved wall plug efficiency up to 42%. These improvements in the blue LED chip allowed the white LED performance of up to 85 lm/W to be realized.
The new 1 mm x 1 mm EZBright LED power chips deliver twice the brightness of Cree's previous generation power chips. Measured as a bare die, the blue EZBright1000 chip offers a maximum power output of 370 mW at 350 mA drive current, and 800 mW at 1 A of drive current.
Typical luminous flux of the white XLamp is 80 lumens at 350 mA, yielding 70 lm/W. A version that produces luminous flux of up to 107 lumens at 350 mA, or 85 lm/W is also available.