7

XLamp a19 RefeRence Design

trademarks of Cree, Inc. For product specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at sales@cree.com.

The table below summarizes characteristics and goals from several bulb designs we review in this application note. all

these designs use hemispheric distribution and are considered non-standard leD lamps in the energy Star vernacular.

Characteristic

unit

40-W-equivalent

“Value” bulb

60-W-equivalent

performance bulb

luminaire light output

lm

450

800

power

w

<10

<13

Efficacy

lm/w

>50

65

lifetime

Hours

25,000

ccT

°K

3,000

3,000

crI

80

80

table 5: general A19 system goals

estimAte effiCienCies Of the OptiCAL, theRmAL & eLeCtRiCAL systems

This section is an estimation exercise and discussion for a variety of LED configurations

and system performance to develop initial approaches for system design.

In all the cases we review here, we are assuming a 15% loss in the diffusing structures of

the leD bulbs. This is a representative loss for the cast-plastic diffusive domes.

For a 40-w-equivalent leD bulb we have set up the pcT to compare system estimation

information for three leDs, the Xlamp mX-6S, mX-6 and Xp-e Hew. The settings of the pcT

are to deliver 450 lumens with an 85%-efficient optical system and an 87%-efficient driver

system. we also assume we have a heat sink that allows the system to maintain a 55°

solder-point temperature.

We have configured the PCT display to focus on system-wide information, looking at the

number LEDs required, lumens delivered, system wattage and efficacy.

4

pct.cree.com

XLamp Xp-e heW Led

XLamp mX-6 Led