Cree XP-P LED pattern arrive


EinW Cree VP-P arrives

I was dying to experiment on some, and they were proving difficult to buy.

They arrived beautifully packaged and even vacuum-wrapped.

XP-P is Cree’s high-intensity led for long narrow beams – it has a 9Wmax 1 x 1mm die with no primary lens. My aim is to pair one with Gaggione’s very nice 35mm LLC15E collimator and try it as a main beam for road use.

Gaggione does not have data for the combination on its website, but it does have data for the LLC15E with an XQ-E HI – another 1mm un-lensed die led from Cree.

They score: ±2.3° by ±7.4° (the beam is elliptical) to 50% centre intensity (so 4.6 by 14.8° FWHM), then ±4.5° by ±10.1° to 10%, and 31.5cd/lm.

The leds are 5,700K (E2) white versions – all XP-P leds are cool white – even the nominally neutral version is 5,000K.

Luminosity is U5 – 360-380 lm at 1A, which, looking at the curve in the data sheet, doubles if the current is tripled to 3A. Forward voltage is 3.1V at 1A and 3.6V at 3A (25°C).

Multiplying the information above: 3A (with sufficient cooling) should deliver at least 33,680cd (360 x 2 x 31.5).

Now to print a holder to check the necessary led-to-collimator-flange distance.

EinW Gaggione LLC15E best mounting positionAt least with a lens-less die, the nominal height of emission is not as vague as when dealing with a lensed die. The XP-P data sheet has a precise 0.75mm from package mounting surface to its optical reference, and the LLC15E (data sheet) requires 14.06mm from its mounting flange to the emissive surface.

Adding these comes to 14.81mm from led mounting surface to collimator mounting flange.

The star substrate to which Cree kindly attached the led samples is 1.15mm thick – making it 1.9mm from final mounting surface to optical reference (I measure 1.93mm to the die phosphor top with callipers).

All told, that is 15.96 mm, which needs adjusting to with 16.0mm to the nearest 3d printed layer.

BTW, getting the first layer thickness correct is the most taxing part of getting a 3D print to an exact height –  there are a lot of parameters to understand.

Watch this space…..


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