White high-output multichip LED

April 04, 2013 // By Graham Prophet
Osram Ostar Stage LEDs from Osram Opto Semiconductors offer high luminance of 48 million candelas per square meter (Mcd/m²) and tunable colour tones from cold white to warm white. Combined with their extremely low-profile design and glass cover with its anti-reflective coating, they provide the basis for compact spotlights with an extremely narrow beam.

This LED is suitable for use in moving head spotlights on stage, fand for architectural lighting. The special feature of the new LED is its tunable white light colour. Two warm-white and two cold-white chips, arranged diagonally in the package, not only enable colours to be mixed at component level but also allow all white tones between colour temperatures of 2700 Kelvin (K) (warm white) and 10,000 K (cold white) to be produced with appropriate control. The LED achieves a high colour rendering index of 94 for warm white and 74 for cold white.

Instead of the usual lens, the LEDs have a flat glass cover with an anti-reflective coating, making them ideal for injecting the light into lens systems. Its etendue (the emission angle/area ratio of the emitting light surface to the projected light surface) in conjunction with external optics is retained, enabling a very narrow beam of light (+/- 9°) to be produced. This beam is smaller by factor of two than for spotlights based on plastic-encapsulated LEDs. Consequently, the luminance of the spotlight is also doubled.

Thanks to the glass cover the Osram Ostar Stage LED also has a much lower profile than previous standard components. At 1.23 mm its height is only one quarter of the usual component height and its footprint is only 5.9 x 4.8 mm. Spotlights can therefore be made very compact.

All the versions of the Osram Ostar Stage are based on the Osram Ostar SMT platform and are suitable for standard solder processes. The chips are fabricated in thin-film technology so that almost all the light produced internally is emitted at the top. The LED is therefore suitable for use with external optics. In continuous operation (DC) the chips can handle an operating current of up to 900 mA. This gives maximum values of 390 lumen (lm) in cold white (10,000 K) and 210 lm in warm white (2700 K). At