Cree Presentation LED

8/10/2019 Cree Presentation LED

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Copyright 2009 Cree, Inc. pg. 1

Lumen Maintenance


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Lumen Maintenance Definition

Definition: change in light output of a light source over operationallife, relative to initially measured light output

Lxx= time to xx% of original light output

L70= time to 70% of original light output

L50= time to 50% of original light output

pg. 2


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50,000 Hours Is

Trivia Point: 50,000 hours is:

137 Years at 1 hour/day

68.5 Years at 2 hours/day


22.8 Years at 6 hours/day17.1 Years at 8 hours/day



pg. 3


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LED Lumen Maintenance History


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LED Lumen Maintenance Critical Parameters

1. TAIRAmbient Air Temperature

2. TJJunction Temperature

3. TSP/ TC/ TSSolder-Point Temperature /Case Temperature

4. IFForward Current /Drive Current


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Cree Lumen Maintenance Model

Degradation in first 5,000 hours is mostly due to degradation inthe silicone encapsulant.

After 5,000 hours, this mechanism drops out and the slower chipdegradation dominates.

Good quality LEDs in well-designed fixtures will last for decades

under normal use and operating conditions.


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How Do You

Know TheyLast >50,000

Hours?

L70Lifetime PredictionIF= 350 mA


8/23Copyright 2009 Cree, Inc. pg. 8

L70Lifetime PredictionTAIR= 45C



L70Lifetime PredictionTAIR= 55C



Low temp (25C) testing is a good surrogate forthe LED chip depreciation1-2% @ TJ= 65C

40,000 Hour / 4.5 Year XLamp Long-Term Data

At lower ambient air temperature, LEDs hardly depreciate at all.

pg. 13



System Lifetime is What Counts

System Lifetime is What Creates Value

LED Lamps: Practically never

fail; depreciate very slowly in a

well-designed system

Optical Components: Can

(rarely) yellow over time and

lose light; system design choice

Driver: Much improvement on

rel and performance especiallywith the large suppliers.

Heat Sink: Linchpin of the entire system.

If this is poorly designed, all the other

components can be compromised



Binning



What is LED binning?

Used to define similar groups of parts by performance characteristics

Not unlike other industries that bin based on performance, ie:microprocessor

Cree XLamp LED binning based on two parameters:

Flux (total light output)Chromaticity (white), Dominant wavelength (color)

Even fluorescent tubes are binned by chromaticity

daylight, warm white, etc.



Two Main Types of Binning

Brightness or Flux Binning

Minimum luminous flux orradiant Flux

Bin sizes (flux range)varies by supplier

Chromaticity or Color Binning

Some defined Boxin thewhite area on or near theBlack Body Locus (White LEDs)

Dominant Wavelength (ColorLEDs)



Brightness or Flux Binning

Flux = total light emitted in all directions

Measured using an integrating sphere



Luminous Flux Binning

LEDs are tested & sorted into luminous flux bins

Performance binning is very standard in the semiconductorindustry (e.g., CPUs), but confusing to the lighting industry whereperformance is very standardized

102.3 lm

Driver

350 mA

Flux:



Chromaticity Binning

Driver350 mA

CCy: 0.35

CCx: 0.32



Design & Specification Strategies

Insist on the tightest binavailable

Pay the highest pricepossible

Strategy #1

Understand light, binning,and your application needs

Do the mixing yourself inyour fixture if theapplication will allow it

Save money

Strategy #2



Let Cree do the mixing for

you...EasyWhite Consistent color

No complicated mixing recipes

Reduced inventory

Ease of manufacturing

Strategy#3

Design & Specification Strategies


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EasyWhite

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