Solid state lighting science and led theory of operation december 2010

David Cox

December 2010

Solid State Lighting Science& LED Theory of Operation

Copyright © 2010 Cree, Inc. pg. 2

Learning Objectives

• Basic intro to LED technology – specifically, White Lighting-class LEDs – and the critical engineering disciplines required to design an LED luminaire

• Develop a high-level understanding of the inter-disciplinary trade-offs needed when designing with LED light sources

• Understand how LED brightness and color binning work, their strengths and limitations

• Learn the role that proper thermal management, driver design, and optical design play in determining key operating parameters and lumen maintenance


LED 101 Outline

• Basic LED Concepts– Theory of operation

– Materials of construction

– LED packages & types

– LED technology

– Color

– Binning

– LED reliability & lifetime projections

• LED Performance in the REAL world

• LED standards status, cost trends

• Final thoughts

We’re Going To Get Our Hands Dirty


2008Production White

LED LampExceeds 100 lm/W

…A Brief History of Lighting

1879Edison Light

Bulb

U.S. 223,898

1901Fluorescent

Tube

~1990“High Brightness”

Red, Orange, Yellow, & Green LEDs

2000White LED Lamp

demonstratesIncandescent

Efficacy (17 lm/W)

1919Sodium

Vapor Lamp

1970sFirst Red

LED1995

“High Brightness”Blue, Green LEDs

2005White LED Lamp

demonstratesFluorescent

Efficacy (70 lm/W)

• Current lighting technology is about 100 years old

• LEDs began as just indicators, but are now poised to become the most efficient light source ever created


One Problem to Address as an Industry…

• We expect top quality, know how to tell when we are getting it, and are willing to pay for it

• We know extravagant marketing claims on this are not realistic

• We know what we are getting when we buy a Yugo

We may not [YET] know how to tell on SSL…

pg. 6Copyright © 2010 Cree, Inc.

16.5” Lowes

Time zero

22” Linear

LED Puck

16.5” Linear97.8% Drop

1000 hours

84.1% Drop

96.9% Drop

Not a Binning Problem (Poor LED Selection)

The LED Matters

Copyright © 2010, Cree, Inc.

pg. 6


• LEDs consist of several layers of semiconductor material

• Light is generated in the PN junction when a current is applied

• Monochromatic (single color) light; must be down-converted with a phosphor

• The color of light from the LED depends on the materials used

• There are two material systems used to produce LEDs in all colors

– Red/Orn/Amber: AlInGaP

– Green/blue: InGaN

LED: Theory of Operation


Materials of Construction

* Guckes Indium Corporation; 22nd EU PV Solar Conference, Milan Italy 4Sep07, p.5-6 http://www.indium.com/_dynamo/download.php?docid=552.

•White, Lighting-class LEDs: • …contain no mercury, metals

• …utilize no rare or exotic materials

• …save A LOT more energy in use thanthey consume in manufacturing

http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/matthews_chicago09.pdf

• …are RoHS compliant

• …contain no substances of very high concern (SVHCs) as defined in the EU REACH program

• …are “Article Exempt” from an EPA TSCA standpoint


LED Packages and Types

Lamp TypeDrive

CurrentLight

OutputBrands Applications

T1-type (3 – 7 mm)

5 – 20 mA <1 – 4 lm (Commodity product)

• Indicators• Novelty lights• Traffic signals• Electronic signs

Surface mount

5 – 20 mA 1 – 10 lm

• TopLED• SideLED• Cree

CLA1A

• Automotive• LCD backlighting• Electronic signs

P4 20 – 100 mA 1 – 20 lm • Piranha• Automotive• Channel letters

High power 200-1500 mA 50-400 lm

• DRAGON• LUXEON• XLamp

XPG

• General illumination

• Portable• Architectural

Multi-small chip

200-700 mA 150-500 lm

• XLamp MX6

• XLamp MLE


Multi-power chip

200-1000 mA 300-3000 lm

• OSTAR• XLamp

MPL• XLamp

MCE



RGB Blue LED + Phosphor

Pros:• Tunable CCT,

colors• Any color

possible

Cons:• Difficult to

control• Low CRI (<50)• Lowest LPW

efficacy (<40LPW*)

Pros:• Single LED type• Easy to control• Easy secondary

optics• Good CRI (~82)

Cons:• OK efficacy

(~40– 60LPW*)

Pros:• Highest

efficacy (+20-30% v. blue + phos*)

• Highest CRI (>90)

Cons:• Complicated

to control

Four Ways To Produce White Light with LEDs

Blue LED + “Remote” Phosphor

+

“BSY” + Red

Pros:• +5-10%

efficacy v. blue + phos

• Good CRI (~82)• Easy to

control

Cons:• High cost due

to complex LED binning

• Rigid form factors* Achievable system efficacy @3000K, varies somewhat by application


Traditional Lamp vs. LED Technology

From an applications standpoint, the most important differences are in:

– Directionality of generated light

•Omni-directional vs. directional

– Means of evacuating generated heat

•Convection vs. conduction

Bulbs:R

efle

ctor

(light)(heat)

LEDs: 90°-140° viewing angle

(light)

(heat)

(light)

Note: Lighting-class LEDs provide a thermal path, typical through-hole LEDs do not


•LED Chip:– Determines raw

brightness and efficacy

•Phosphor system:– Determines color point

and color point stability

•Package:– Protects the chip and

phosphor

– Helps with light and heat extraction

– Primary in determining LED lifetime

LED Technology


Chip Architecture Features

• A photon is a terrible thing to waste…

– Surface Features

– Beveled saw cuts

– Internal mirrors

– Thin Film

– Flip-chip

XT

Mirror layer

Wire Bond Pad

AlInGaNlight emittinglayer

Backside ohmic contact metal

SiCMetal bonding layer


n-AlInGaN

Mirror layer

Wire Bond Pad

AlInGaNlight emittinglayer


Metal or semiconductorMetal bonding layer



Raw Efficacy Enables More Applications

2007 2008 2009 2010 2011 2012

Parking Deck

Roadway

Downlights

PAR lamps

MR16 lamps

A-lamps

T8 lamps

High Bay

70

100

65

X

X

X

X

X

100

150

100

?

?

?

X

X

175

250

150

50-60

20

?

?

?

Value

400

60-70

20

40

?

400

400

70-90

35

60

32

400

Value

90+

50

75

32

400

Approx Wattage Equivalents


Implication #1: LEDs Are – Today – The most efficient commercially available white light source and improving all the time…

• Beyond saving real dollars on energy, a couple non-obvious things happen when the LEDs become more brighter and more efficient:– Fewer LED are required for a given lighting

application

– Brighter LEDs enable penetrating higher and higher-volume lighting applications

Value

MR16

200920112012

MR16 Volume by Wattage

Technically Viable in


LED Chips: Analog Components

• Light output and LPW efficacy varies with input drive current

• Different LED types are BINNED at different currents• No such thing as “OVERDRIVING” an LED– Driving above (or below) the binning current is accepted

and expected– Watch thermals and LM-80 data at high drive currents

Input Current (If, mA)

Binning Current (mA)

“Droop”

LPW efficacy

Lig

ht

Ou

tpu

t, E

ffic

acy

Light OutputMax Drive

Current (mA)


Chip Name

PicChip Size

(mm)

Typical*

Binning

Current (mA)

Current Density

@ Binning Current (A/cm^

2)

Typical Light

Output at Binning Current*

(lm)

Max Drive

Current*

(mA)

Light Output @ Max Drive

Current (lm)

Current Density @ Max Drive

Current (A/cm^

2)

TR 3500.35x0.47m

m20 12.2 20 167 47 101.3

EZ7000.7 x

0.7mm350 71.4 94 500 139 102.0

EZ1000 1 x 1mm 350 35 114 1000 252 100.0

EZ14001.4 x

1.4mm350 17.9 130 2000 551 102.0

LED Chips: Size Doesn’t Matter

• Small chips droop; Big chips droop• Small chips sometimes appear to have higher efficacy since

they are customarily binned higher up the droop curve• Primary real difference (not an advantage or disadvantage)

is in the optics very application-specific

* Typical data sheet of packaged LED lamp


Engineering Trade-off between:

• Efficacy (LPW)• ∆CCT• Source size

• Color Stability•Reliability•Cost

• Binning• IP• Color

Phosphor Deposition Approaches

4. Chip coating or plate3. Conformal coating

1. Glob 2. Dispersed in encap


Typical Lighting-class LED Package

The LED Package provides:– Protection for the LED chip from the outside environment– Conductive path to carry generated heat away from the LED chip– RI matching from the LED chip to air

Reliability– Lens & encapsulant systems should not discolor under

UV and exposure to high amounts of luminous flux

LED chip, RI~2.2

Substrate

Air, RI = 1.0

Lens, RI ~1.4

Wire Bond

Phosphor


LED Packaging Trends

• Application-specific• Smaller size• Multiple high power chips• Multiple small chips• Phosphor coatings vs. glob or

dispersed• Higher wattage packages• Deposited silicone primary

lens systems• “Fried Eggs”

Last Gen Packages

New Gen Packages


Cree XLamp LED Product Portfolio – Lighting

Copyright © 2010, Cree, Inc.

pg. 21

XLampSingle Die Multiple Die

XR-C XR-E XP-C XP-E XP-G MX-6 MC-E MP-L

Footprint (mm)

7.0 x 9.0 3.45 x 3.45 6.5 x 5.0 7.0 x 9.0 12 x 13

Max Current

500 mAUp to 1.0 A

500 mA

1.0 A 1.5 A 1000 mA 700 mA (per LED)

250 mA(per string)

Viewing Angle

90° 90° 110° 115° 125° 120° 110° 125°

LM-80 accepted

LM-80 accepted

LM-80 accepted

LM-80 accepted

LM-80 accepted

LM-80 accepted


∆CCT

• Indoor linear applications are particularly sensitive to this and can benefit from an LED with good ∆CCT control

• In general, Outdoor lighting is very forgiving on this


Relative Advantages of the Approaches

Small-chip, dispersed phosphor

Pros:• ∆CCT, uniformity of

light• LM-80, Energy Star

Cons:• Limited drive

capability

• Generally higher VF

• Large source size for secondary optics

Large-chip, coated phosphor system

Pros:• Much higher drive

capability

• Generally lower VF

• Small source size; good for TIR optics

• LM-80, Energy Star

Cons:• ∆CCT, uniformity of

light

Fried Eggs

Pros:• Tons of light –

thousands of lumens

• Ease of use

Cons:• Lower efficacy• Thermal & binning

challenges• No LM-80, Energy Star• Huge optical source


Describing Color: Numbers & Words

Spectral Power Distribution(~100 numbers)

Chromaticity (xy or HSB))(2-3 numbers)

Color Temperature(1 number)

“Warm White”

Descriptive Prose(Language)


Visible Light Spectrum of Various Sources

• Which one is closer to the Sun?• Normalizing Incandescent to CRI = 100

makes the CRI scale somewhat arbitrary• New standards – such as Color Quality

System (CQS) is currently being considered for ALL light sources

LED

FL HID

The Sun

Incandescent


Color Temperature Discrimination

• People’s ability to discern differences in color vary by CCT

• Specify your LEDs and design your systems tightly for indoor/warm colors; more loosely for outdoor/cooler CCTs

– 3000K +/- 50K– 4000K +/- 90K– 5000K +/- 140K– 6500K +/- 240K

Color Temperature Discrimination

0

100

200

300

400

500

600

700

800

0 2000 4000 6000 8000 10000 12000

Color Temperature (K)

Ju

st

Noti

ceable

Ch

rom

ati

cit

y

Diff

ere

nce (

K)

Source: Wyszecki and Stiles, Color Science


Color Rendering Index System

1

3

4

5

6 7

8

3000

4000

6000

2500

2

D659

10

11

12

13

14

• First proposed in the 1950’s

• Based on color comparison of 8, then14 sample tiles with unsaturated colors

• Incandescent bulbs are – by definition – CRI 100

• RGB LEDs have fully saturated colors and actually pay a mathematical penalty in the CRI system


CRI of Selected Light Sources

1 2 3 4

5 6 7 8

9 10 11 12

13 14

Source CRILow Pressure Sodium <5

High Pressure Sodium 20

RGB LED (typical) 31

Mercury Vapor 43

Cool White Fluorescent 63

Metal halide 64

Cool White LED 70

Daylight Fluorescent 76

Warm White LED (YAG) 81

Tri-phosphor Fluorescent 82

F32T8 Tri-phosphor 85

BSY + R LED 93

Halogen MR16 99

Incandescent 100


Color Rendering/Color Quality In Real Life

CRI = 62 CRI = 93

CRI = 80 CRI = 92


•David MacAdam – a scientist at Kodak – performed the first basic research in the late 1940’s

•Found a JND (Just Noticeable Difference) in color varied statistically by observer, size, and orientation in CIE 1931

MacAdam Ellipses

One Step(68.3%)

Two Step(97.5%)Three Step

(99.7%)

Note: shown 10x actual size


Binning – Root Cause

• The human eye is extraordinarily sensitive, so small process variations in LED chip wavelength; phosphor thickness, concentration, composition; and/or deposition conditions make a big perceived difference in white light CCT & quality

Blue LED

White Light

YellowPhosphor


Binning – Two Types

• Chromaticity binning

– Some defined “box” in the white area on or near the Black Body Locus

– Bin sizes (x, y coordinates) varies by supplier

• Brightness or LF binning

– Minimum luminous flux (most suppliers)

– Bin sizes/flux range varies by supplier


Luminous Flux Binning

119 lm

Driver350 mA

Flux:

25ºC


Chromaticity Binning

Driver350 mA

CCy: 0.41CCx: 0.445

25ºC


LED Testing Conspiracy…?

• LEDs are manufactured in very high volume

• LEDs go into a many different applications and operating environments

• Light output is diminished as a function of temperature

NIST Comparison of Pulse vs. Steady-State*

* Y. ZONG, Y. OHNO, National Institute of Standards and Technology, NEW PRACTICAL METHOD FOR MEASUREMENT OF HIGH-POWER LEDS, p.4, CIE SYMPOSIUM, July 2008

• Therefore, LEDs are tested in the factory at ~20ms pulse at 25ºC testing rather than steady-state

• A new IES LM standard is being proposed for pulse LED testing

No Difference!


LED Bins in Context

ANSI C78.377A

~4-step MacAdams

~7-step MacAdams

~2-step MacAdams

Cree EasyWhite™~2/4-steps


LED Yield to Bin

* For illustrative purposes only, not actual data

Yield Loss

Some bins zero yield


LED Color History

2007

2009

2006

ANSI C78.377-2008 3000K Quadrangle

2010

2-step

4-step


The LED junction is the area of the chip that actually creates light. Under normal operation, this area of the chip will get hot

LED Junction Temperature (TJ)

Running an LED above its rated maximum junction temperature will decrease its active lifetime and accelerate its lumen maintenance loss

The LED junction temperature is affected by:• Ambient temperature of the LED’s immediate surroundings

• Thermal path between the LED junction and ambient conditions

• Power dissipated by the LED

The LED junction temperature is measured by:• Measuring the board temperature (Solder Point)

adjacent to the LED (TSP)

• Computing the junction temperature (TJ) based on the drivecurrent and data sheet parameters (RTH) is straight-forward


Junction Temperature Calculation

• TJ = TSP + RTH * IF * VF

– TSP is solder point temperature

– RTH is the thermal resistance of the LED in ºC/Watt (LED datasheet)

– IF is the forward current in Amperes

– VF is the forward voltage in Volts

• Example:– TSP = 60 ºC

– RTH = 9 ºC/Watt (from data sheet)

– IF = 700mA (0.7A)

– VF = 3.2V

TJ = 60 + [(9) * (0.7) * (3.2)] = 80 ºC

TSP


Thermal Path is Critical to LED Lifetime

• 5mm lamps have almost no thermal path

• RTH >350ºC/W typical

• Chip (TJ) and phosphor can essentially cook themselves

• Lighting-class LEDs are designed for high temp operation

• RTH <10ºC/W typical

• Lamp can stay within data sheet parameters with good thermal design

Thermal path

Lighting-class LED5mm LED

No Thermal path


Trivia Point: 50,000 hours is:

137 Years at 1 hour/day68.5 Years at 2 hours/day34.2 Years at 4 hours/day22.8 Years at 6 hours/day17.1 Years at 8 hours/day11.4 Years at 12 hours/day5.7 Years at 24 hours/day


LED Lifetime

40%

50%

60%

70%

80%

90%

100%

110%

0 10 20 30 40 50 60 70 80 90 100

Operating Time (k hrs)

Lu

men

Ou

tpu

t (%

)

100 W Incandescent5mm LED42W CFL

50 W Tungsten Halide400 W Metal Halide25 W T8 FluorescentLighting-class LED

• Lighting-class LEDs become dimmer over time with no catastrophic failure

• End of life defined by the LED becoming too dim – needed to define Lumen Maintenance (L70)

• Not all LED types have long lifetime

Courtesy LRC, Rensellaer Polytechnic Institute


Semiconductor Reliability Testing

• Reliability test methods and acceptance criteria for semiconductor components have been standardized (JEDEC, EIAJ, others…) and practiced for decades– Think: processors, regulators, microcontrollers, etc..

If you’ve recently flown in an airplane, driven in a car, or talked on a cell phone, you’ve trusted your life on this body of scientific work and testing…


LED Reliability Testing

• LEDs are semiconductor components that happen to emit light…

• Most LED manufacturers conduct standardized semiconductor component reliability testing – the same tests Intel tests their microprocessors with – on their LED lamps

• The Illumination Engineering Society of North America published IES LM-80-2008 18 months ago to characterize the Lumen Maintenance aspect of LED semiconductor components

• Note: Lumen Maintenance ≠ LED Lifetime. Another standards committee – TM-21 – is working on that aspect of the problem


LEDs Last Forever!! [under ideal conditions]

Well-designed systems with Lighting-class LEDs at low TA, TJ will run a very, very long

time…


Predictive Algorithm* Under Real Conditions

2,000 4,000 8,0006,000 10,000 12,000 14,0000

70

80

110

90

“A” “B”

5,000

% L

F

Slope A =ΔyA

ΔxA

Slope B =ΔyB

ΔxB

100

• Air Temperature (TA)• Solder Point Temperature (TSP)

• Junction Temperature (TJ)• Drive Current (IF)

Comprehends:

* One of several under consideration by TM-21 committee


Typical Lighting-Class LED Lifetime


LED Lifetime Is Irrelevant

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: Currently the weakest point of the system, but the big companies are working on this

Heat Sink: Linchpin of the entire system. If this is poorly designed, all the other components can be compromised


SSL Luminaire: Multi-Disciplinary Effort

Delivered

lumens

Electrical

• Integrated systems approach required

• LED light is different than existing light technologies

• Not intuitive at first

Thermal Delivered

LPW

• These charts are on all LED data sheets; familiarization with them is essential to good results

Optical


Lumens, LPW in the REAL World

1. Find 700mA point on relative intensity curve

2. Typical LF should be:

LF = 87.4 lm * 175%LF = 154 lm

EASY!!

Case Study:Can Light, 650 lumensWarm white (3000K) XLamp XP-E, Q2 LF Bin (87.4 lm)700mA IF


Lumens, LPW in the REAL World, p.2

3. Determine your thermal pad temperature (Tsp)– Requires

measurement

LF = 134 lm

Assume Tsp = 60°CLF = 154 lm * 87%

EASY!!




4. Find 700mA on VF curve

VF = 3.36V @ 25ºC

5. Calculate VF @ 60ºC from data sheet (TCOV)

VF = VF@25ºC –(TCOV(60-25))

VF = 3.36-(0.004(60-25)) VF = 3.22V @ 60ºC

6. LPW = lumens / Watts= lumens / VF * IF

= 134 / 3.22 * 0.7= 59.6 LPW

EASY (kind of…)!!



Optical Losses

Secondary Optics

Reflector

Lens

85%-90% Efficient 75%-95% Efficient

Diffuser


Driver Losses

60

65

70

75

80

85

90

0 20 40 60 80 100

Output Load (% )

Effi

cie

ncy (

%)

Generally, 80% - 85% is a good estimate – but some will claim MUCH

higher


Your Boss shows you press releases from LED companies and the spec sheets of LED

luminaires from your competitors and wants to

know why your design is so uncompetitive?


7. Assume:– 86% Efficient

Diffuser– 80% Efficient Driver

Delivered Lumens, LPW= 134 * 86% (optical loss)= 115 lumens= 115/3.22 * 0.7= 51 LPW, 6 LEDs needed, ~650 lm

= 51 LPW * 80% (driver loss)= 41 LPW (wall-plug, delivered LPW)


• SSL generally outperforms CFL bulbs with higher rated lumens– Tested delivered lumens using max lux from 9’8” height across variety of CFL

sources and popular fixture and trim kit options– 700lm SSL outperforms even 1750lm CFL on all but one configuration

• Tests demonstrate high delivered lumen efficiency of 700lm SSL

*Measured at 9.8ft height using high volume downlight fixture

Ma

xim

um

Lu

x*

Lumen Comparison: Rated vs. Delivered


0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

0 100 200 300 400 500 600 700

Drive Current (mA)

Rela

tive I

nte

nsi

ty (

%)

Iterative Process: More Power = More Light…


0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

0 100 200 300 400 500 600 700

Drive Current (mA)

Rela

tive I

nte

nsit

y (

%)

0

10

20

30

40

50

60

70

Effi

cacy (

lm/W

) '

…But More Power = Lower Efficacy (Droop)


•There is often an opportunity to trade-off drive current and thermal design for both system LPW (efficacy) and overall system cost

Wide Operating Range is Key to Optimization

If(mA) 700 550 400

LPW 41 44 48

# of LEDs 6 7 9

Energy Star? No

Cost $ $+ $++


System: 650 86% 80%

Model Model Model

Flux Q2 [87.4] Tj (ºC) 25 Flux Q2 [87.4] Tsp (ºC) 60 Flux Tsp (ºC) 25

Price -$ Price -$ Price 2.10$

SYS # LED SYS lm/ W LED Vf LED lm SYS # LED SYS lm/ W LED Vf LED lm0.100 28 64 2.99 28 30 60.7 2.87 26 #N/A #N/A #N/A #N/A0.150 19 62.2 3.03 41 21 58.2 2.91 37 #N/A #N/A #N/A #N/A0.200 15 59.3 3.08 53 16 55.6 2.95 48 #N/A #N/A #N/A #N/A0.250 12 57.4 3.12 65 13 53.3 2.99 58 #N/A #N/A #N/A #N/A0.300 10 54.7 3.16 76 12 51.9 3.02 69 #N/A #N/A #N/A #N/A0.350 9 53.6 3.2 87 10 50.1 3.06 78 #N/A #N/A #N/A #N/A0.400 8 51.7 3.24 98 9 48.4 3.09 87 #N/A #N/A #N/A #N/A0.450 7 50.6 3.27 108 8 47.4 3.11 96 #N/A #N/A #N/A #N/A0.500 7 49 3.3 118 8 45.4 3.14 104 #N/A #N/A #N/A #N/A0.550 6 48.1 3.33 128 7 44.1 3.16 112 #N/A #N/A #N/A #N/A0.600 6 46.9 3.35 137 7 43.1 3.18 120 #N/A #N/A #N/A #N/A0.650 6 45.8 3.38 146 6 41.9 3.2 127 #N/A #N/A #N/A #N/A0.700 5 44.4 3.4 154 6 40.9 3.22 134 #N/A #N/A #N/A #N/A0.750 5 43.3 3.42 162 6 39.7 3.23 140 #N/A #N/A #N/A #N/A0.800 5 42.2 3.44 169 6 38.9 3.24 146 #N/A #N/A #N/A #N/A0.850 5 41.2 3.45 176 5 37.7 3.25 151 #N/A #N/A #N/A #N/A0.900 5 40.4 3.46 183 5 36.6 3.26 156 #N/A #N/A #N/A #N/A0.950 4 39.5 3.47 189 5 35.6 3.26 161 #N/A #N/A #N/A #N/A1.000 4 38.6 3.48 195 5 34.7 3.27 165 #N/A #N/A #N/A #N/A1.100 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.200 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.300 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.400 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.500 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.600 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.700 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.800 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A1.900 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A2.000 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A

Cree XLamp XP-E {CW/NW/WW} Cree XLamp XP-E {CW/NW/WW} (none)

Target Lumens : Optical Efficiency: Electrical Efficiency:

Curr

ent

(A)

Pass #1: 25'C Tj Pass #2: 60'C Tsp LED 3

Tools For Doing It: Product Characterization Tool (PCT)

www.cree.com/PCT


Real LED Levels of Performance (Current)

• Just like traditional lamps, ballasts and fixtures, LEDs have losses beyond the boiler plate data sheet specs…

• …but the source of losses are somewhat different:– Thermal (also a source of Lumen Depreciation)– Optical (lenses, etc.)– Driver (electrical losses in power conversion)

6000K 4100K 3500K 2700KData Sheet LPW 150 135 121 108

Typical* Thermal Loss 10% 10% 10% 10%

Typical* Optical Loss 10% 10% 10% 10%

Typical* Driver Loss 15% 15% 15% 15%

Achievable* LPW 98 88 78 70

CRI ~75 ~80 ~82 ~83

* Typical w ith average/good design practices


Projected LED Levels of Performance (2012)

• LEDs will be the most efficient mainstream light source available• >100 delivered LPW roadway light possible• Indoor fixtures >90LPW (wall-plug)

6000K 4100K 3500K 2700KData Sheet LPW 180 162 145 129

Typical* Thermal Loss 10% 10% 10% 10%

Typical* Optical Loss 10% 10% 10% 10%

Typical* Driver Loss 15% 15% 15% 15%

Achievable* LPW 117 105 94 84

CRI ~75 ~80 ~82 ~83

* Typical w ith average/good design practices


SSL Standards (U.S.)

• 4 years ago: Major objection to LED• Today:

– RP-16 – SSL Definitions– ANSI C78.377 – chromaticity– IES LM-79-2008 – SSL photometry– IES LM-80-2008 – Lumen Maintenance– UL 8750 – Safety

• Most of the major piecesare in place, many more onthe way…

• Being practiced and referenced widely by industry and governmentprograms

RP-16 – SSL Definitions

ANSI C78.377

LM-79

LM-80

UL 8750

TBD


SSL Standards Status

Standard Draft Comment Comment Resolution

Publication Status

IES RP-16Definitions X X X Complete

ANSI BSR C78.377A, Chromaticity

X X X Complete

IES LM 79, Luminous Flux X X X Complete

IES LM 80, Lumen Depreciation X X X Complete

NEMA LSD-44, 45, 49 (White Papers)Best Practices for SSL Interconnect, Sub-Assemblies, Dimming X X X Complete

ANSI C82.77, Harmonic Emission Limits – Related Power Quality Requirements for SSL X X X Complete

NEMA SSL-1, SSL Drivers X X X Complete

NEMA SSL-3, LED Lamp Binning X X X

NEMA SSL-4, Physical, Mechanical Standard for LED Retrofit Lamps

NEMA SSL-6, Dimming Practices for SSL Integrated Lamps X

NEMA SSL-6, Dimming Practices for SSL Integrated Lamps X

NEMA-ALA Joint White PaperDefinition of Functional & Decorative Lighting X X X Complete

UL 8750LED Safety X X X Complete

IEC 62471-2, IES RP-27Photobiological Safety X X X Complete

IES TM-21LED Lifetime X

CIE TC1-69,Color Quality System X

47 CFR Part 15 (FCC)Radio Frequency Emissions for SSL Components, Drivers X X X Complete

IEC 62471-2, IES RP-27Photobiological Safety X X X Complete

Status of NEMA, ANSI, IES, IEC, and CIE Solid State Lighting Standards (Partial List)

Rev. 5-Aug-10


0.31

0.32

0.33

0.34

0.35

0.36

0.37

0.38

0.39

0.40

0.41

0.42

0.43

0.44

0.45

0.30 0.31 0.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39 0.40 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48 0.49 0.50

CCx

CC

y

BBL+

2700 K

+

3000 K

+

3500 K

+

4000 K

+

4500 K

+

5000 K

+

5700 K

+

6500 K

ANSI Fluorescent Lamp StandardANSI C78.377A LED Standard

ANSI Chromaticity Standard


NEMA SSL-3 Binning Standard

ANSI C78.377A SSL Chromaticity Standard

New NEMA “SSL-3” Binning Standard

Under Development


This Has Happened Before….

VHS

Vacuum Tubes

Film

CRTTV

Light Bulbs/ Fluorescent

Tubes

Transistors

1940s – 1960s

DVD

1980s – 1990s

Flat Panel

TV and Display

s

1990s – 2000s

Flash Memory1990s –

2000s

Solid State

Lighting2000s – …

“Brick” phones

Smart phones1990s –

2000s


Moore’s Law for Transistor Cost

-36% CAGR


Four-year Lighting-class LED Snapshot

• >88% reduction in $/lm (plus 65% LPW improvement)

• 100’s of Millions of Lighting-class LEDs shipped

• Driven by brightness, package and process improvements &

volume

Cool W

hit

e (

6000K

)N

orm

alize

d $

/lm

XR59 lmXR

59 lm

XR-E80 lmXR-E80 lm

XR-E100 lmXR-E100 lm XP-E

110 lmXP-E110 lm

XP-E120 lmXP-E120 lm

XP-G130 lmXP-G130 lm

-47% CAGR


Generic Outdoor SSL Economics

Payback (years)

1st Gen BetaLED

105

SSL fixture technology improvement will have

at least as much impact as LED Technology

MH CoOLED CoO

1st Gen

2nd Gen BetaLED

• 30% + efficacy• 40% lower cost

2nd Gen

Cos

t of

Ow

ners

hip

($)

Slope = energy $$

Maintenance Event

First Cost


Final Thought…

• LED lighting systemscan deliver real energy,real maintenance, and real environmental benefits – today – andperformance is increasingall the time

• Taking a multi-disciplinary approach – light source driver thermal optics – is required to get quality results

• You don’t have to be a “shade tree” mechanicto use LEDs – but for the time being, it is helpful…

Business

Solid state lighting science and led theory of operation december 2010