full technical analysis - alphaled · projection lighting - 30 sept, 2009 • voltage drop is a...

Full Technical Analysis

Contents

• Specification summary• XSM technology• Background (Information per specification point)• Reliability• Usage

• Electrical• Dimming• Thermal• Optical

• Benchmarking

Projection Lighting - 30 Sept, 2009

Alpha LED / Xicato Spot Module: Specification summary

The Xicato Spot Module (XSM) is the first genuine LED equivalent for halogen with no compromises: not aesthetic or light technical.

Aesthetic – Compact: similar size to MR 16 lamps– Allows enhanced creativity in luminaire design

Light technical– Similar intensities possible compared with 20-50W low voltage halogen lamp

range– Choice of Colour temperatures (2700, 3000 and 4000K)– Consistent colour (Colour point consistency <2 SDCM part to part)– Natural colour appearance (colour point on BBL - absolutely no 'binning')– Colour Rendering Index of 80+ or 97 (with R9 > 90)– Uniform beam (intensity and Colour Temperature – no yellow ring or shadows)


Advantages (beyond light technical thresholds)

• Cost of ownership (life and efficacy advantages):

– 8 - 23W XSM wattage compares with 20 – 50W low wattage halogen lamp wattage– 50khr XSM life (to 70% lumen maintenance) compares with 2-4khrs low wattage halogen

lamp life

• Extremely low heat (IR) and UV in beam

• No mercury or lead

• IP66 (ideal for outdoor usage)


Alpha LED / Xicato Spot Module: Specification summary

XSM technology


Patent pending internal optical mixing cavity

Patent pending thermal design

Patent pending Corrected Cold Phosphor' technology

LEDs (not to scale)

Allows enhanced creativity in luminaire designProjection Lighting AlphaLED range:


Visit www.alphaled.co.uk for more information

http://www.alphaled.co.uk/�

Similar intensities possible compared with 20-50W low voltage halogen lamp range

Peak intensities with typical 70mm reflectors


Product FWHM Beam Angle

20deg 40deg 60deg

400lm 1200cd 640cd 400cd

700lm 2100cd 1120cd 700cd

1000lm 3000cd 1600cd 1000cd

Similar intensities possible compared with 20-50W low voltage halogen lamp range


Typical 70mm Diameter Reflectors 54mm & 94mm Diameter Reflectors

Choice of Colour temperatures(2700, 3000 and 4000K)


Consistent colour(Colour point consistency <2 SDCM part to part)


MacAdam 1942Visual sensitivities to color differences in daylight

J. Opt. Soc. Am. 32:247-274

1 step just noticeable difference2 step required for white scenes4 step acceptable for colored scenes


Industry best colour consistency performance via Corrected Cold Phosphor TechnologyTM

•Tuning of phosphor to match aggregate wavelength of LED array

•Separated thermal path of front plate and LED array keeping phosphor cold thus temperature effects on the different phosphors in the mix minimised

The Xicato specification (red box dimensions) for 2700K is +/-40K in CCT, +/-0.001Duv, 3000K is +/-50K,

+/-0.001Duv, and 4000K is +/-70K, +/-0.001Duv.

Result- Consistent colour (Colour point consistency <2 SDCM part to part)

Consistent colour (Colour point consistency <2 SDCM part to part)


• CIE 1931 diagram, focused on the 3000K point.

• Data points represent colour points of approximately 1000 XSM 3080-01 modules, manufactured in January 2009. All units produced are shown.

• All modules are within 3 MacAdam Ellipses

• 99% of the modules are within 2 MacAdam Ellipses

• CRI distribution shown below

CRI %

81 14

82 82

83 4

Natural colour appearance (color consistency <2SDCM)

• Moving away from BBL even with the same CCT would affect colour appearance.

• Moving above BBL moves towards green would increases flux but results in a poorer colour quality

• All XSM colour points are on BBL


Colour Rendering Index of 80+ or 97 (with R9 > 90)


CRI 80

CRI 90

•By using different phosphor mixes CRIs of 80+ or 97 are available

•80 + modules have a 20% higher efficacy

•97 modules have industry best colour rendering properties, including vivid red portrayal (R9>90)

97 CRI Series- 2700K Module


CRI = 97 (Typ) (95 Min)

Spectra Artist, (T=70°C)

Ra R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15

Standard 84 85 89 91 86 83 85 88 69 27 72 85 66 85 94 79

Artist 97 96 98 98 96 96 95 98 98 99 97 94 90 96 98 98



CRI = 97 (Typ) (95 Min)



Standard 81 80 85 89 81 78 80 86 66 16 64 79 58 81 93 75

Artist 98 98 99 98 98 98 97 98 98 98 99 98 88 98 98 98



CRI = 97 (Typ) (94 Min)



Standard 84 83 89 92 83 82 83 89 70 22 71 79 63 84 95 79

Artist 97 98 99 99 94 96 97 95 95 92 99 95 78 99 99 96

Uniform beam (intensity and Colour Temperature – no yellow ring or shadows)

Alpha LED / XicatoTypical Halogen LED Array

Halogen lamps and LED arrays can suffer from local variations of light over a surface due to non-uniform illuminance of the source. The Xicato module has a uniform

(Lambertian) emitting disk as source, which is reflected in the beam.


Reliability

Reliability Goal

Demonstrate industry best reliability and lifetime consistency in a package that is durable easy to integrate

• Perform independent tests on Xicato product range to verify lifetime predictions in a variety of conditions (high temperature, high humidity, elevated drive levels, power cycling)

• Test in accordance with IESNA-LM-80-08 in order to meet Energy Star Requirements

• Tests to be performed out to 6000 hours• Achieve IP66 certification for outdoor and rugged applications• Achieve UL Class 1 recognition for entire product range


Reliability Testing Methodology


The lighting industry is flooded with LED claims of “50k hours”, many of which have not been verified or tested to any degree. Although Xicato uses LEDs from manufacturers who have claims of “50k hours”, complete module reliability is independently tested in Wet High Temperature Operating Life and High Temperature Operating Life.

• Wet High Temp. Operating Life (WHTOL) test at 85C & 85% R.H. Power 1 hr. on/ 1 hr. off per EIA/JEDEC Standard Test Method A101-B.• XSM Optical Test time point intervals at 1,000 hour intervals for LM-80-08 requirements.

WHTOL Reliability Test System for Hallberg-Peck Acceleration Factor

HTOL Reliability Test System for Arrhenius & drive current Acceleration Factor• HTOL 55C, 85C, and XSM maximum rated temperature per IESNA LM-80-08. • Lumen maintenance & color point stability 1,000 hour test time point intervals.

Inside

Results DataLumen MaintenanceColor Point StabilityCRI MaintenanceAbnormal Failures

Accurate & comprehensivereliability predictions

over time, temperature,humidity and drive current

WHTOL Results- Lumen Depreciation


WHTOL Results- Color Maintenance after 1000 hours


3000K 4000K

4 MacAdam Ellipse (SDCM)Xicato Specification

•Each set of points represents a different module under test.•Multiple data points represent different WHTOL test time intervals

All data points are within the 2 MacAdam ellipse Xicato color specification limit.

WHTOL Results- CRI Maintenance after 1000 hours


Average CRI shift ≤0.25 0 Modules have a shift greater than 1

Additional Reliability Notes

• The Xicato XSM is an extremely rugged package. It is IP66 rated and does not require any special handling precautions to protect phosphor coatings, LED domes, or other sensitive materials.

• The Xicato XSM uses flip chip LEDs that do not have wire bonds. The wire bonds for many LED solutions are the prime location for failures and often result in a “open” failure that can wipe out an entire LED string or product. Also, wire bond based LEDs are usually susceptible to failures at low temperatures due to thermal shock (fast heating and expansion of bond at turn on).


Summary of Reliability results

• The 700lm product has completed 3,000 hours of WHTOL 85C & 85% Relative Humidity with better than ENERGY STAR standard requirement at high temperature operation only for the SSL lumen maintenance lifetime prediction.

• The 1000lm product has completed 1,000 hours of WHTOL tests with a color point consistency within a 2 MacAdam ellipse Xicato specification.

• The 1000lm product has completed 1,000 hours of WHTOL tests with an average CRI shift of 0.25.

• The 700lm and 1000lm products are UL Recognized LED Modules.

• The XSM product range has passed IP66 certification.



Electrical

XSM Electrical Operating parameters

• The XSM product range is a constant current device where light output is directly related to drive current

– Module can be run anywhere between 1mA to 1000mA (1A)– Operating above 700 mA is not recommend– Operating above 1000mA may cause permanent damage

• In order to operate at the desired drive current, the supply voltage must be equal or greater to the maximum voltage specified for that drive current in the specification table. An under supply of voltage will result in lower than expected drive levels.

• Multiple XSM units connected to a single driver should be run in series (rather than parallel) to avoid uneven current sharing between modules (see next slide).


Uneven current sharing “Current Hogging”

• Each XSM module may have a slightly different forward voltage (Vf)

– This is a result of the manufacturing variance in forward voltage at the LED chip level

• Due to the physics of LEDs, current is exponentially dependent on voltage, so a small change in voltage could have a large impact on current

• Uneven current sharing can lead to the following potential issues:

– Overstressing 1 or more modules (more current than expected), leading to reliability problems

– Unbalanced light output- 1 or more modules look brighter or dimmer than the others


If If

Wire Lengths and Voltage Drop (Copper Wire)


• Voltage drop is a reduction in voltage in an electric circuit between the source (driver) and a load (XSM) due to the resistance of the wire or cable

• If the voltage drops below operating forward voltage of the XSM, full drive current may not be supplied to the module

• Using smaller gauge wire increases voltage drop.• When wiring XSMs, never use wire gauge that is thinner than 24 AWG (.5 mm^2)• In addition to voltage drop, line noise, shielding and EMI should be considered

when using a remote driver.• The formula below can be used to calculate maximum distance between the driver

and the XSM

D=(Vd-Vfmax)/(I x Rw)

Vd= Max output voltage of driverVfmax= Maximum Vf for intended XSM (see spec table)I= Intended drive current (Amps)Rw= Wire ResistanceD= Maximum routed distance XSM to Driver (meters)


Dimming

Color Stability Over Current


4 SDCM

and pc-white LEDs experience peak wavelength shifts when dimmed. Shift toward "blue" with increases in current: band fillingShift toward “red” from temperatureSmall shift with temperature

InGaN-based blue, green, and pc-white LEDs experience peak wavelength shifts when current is changed (analog type dimming).

• Shift toward "blue" with increases in current, but still well within XSM specification

4 SDCM

CRI Stability over Current

The XSM is extremely stable in terms of CRI vs current– Slight shifts with increasing current favoring better color rendition



Thermal

Why Is Heat Transfer and Temperature Important?

Reason 2: Reliability & LifetimeLifetime (reliability) increases as the temperature of the LED decreases


Maximize Lifetime and Reliability by Minimizing Temperature

LEDs- Why Is Heat Transfer and Temperature Important?

Reason 1: PerformanceLight output increases as the temperature of the LED decreases


Maximize Performance by Minimizing Temperature

At 50C test point temperaturethe XSM will get approximately

7% more light (compared to 70C). For 4000k module, this adds 50lm.

Add efficiency To this axis

XSM Thermal Interface


LargeHeat

TransferAreas

Both the designated heatsinkand the reflector assembly (if metal) can be used to conduct heat away from theXSM.

Heatsinking- Using a Luminaire(EFD Software Demo cont.)


Ttp=85°C

Surface temperature distribution

Cross section temperature distribution and flow pattern

Noticed no temperature change when orientation change.


Optical

Xicato module as Lambertian source

XSM module is close to a Lambertian source– Can be considered as Lambertian for practical

purposes– Measured ray trace and photometric files

available for reflector and optic design from Xicato


Reflector Design for XSM

• Beam angle and center beam intensity are directly related to the output diameter of the reflector (see plots below)

• Reflector length helps control the cut off angle (total field of view)



Benchmarking

Accurate to 2 MacAdam ellipsesAs mentioned above, variations in chips and conformal phosphor coating on traditional LEDs result in complicated and undesirable “bins” that integrators and end users are forced to live with.Xicato's design and manufacturing process allowed for a specification to be developed that appealed and was acceptable to OEMs, specifiers and end users. To define a specification, there needed to be a start point and it made sense to start with the US NEMA specification required to meet US Energy Star requirements (equivalent to roughly 7 SDCM). When shown to OEMs and specifiers the result was clearly unacceptable due to large variation in CCT (white color) and DUV (color across the black body line- green above, pink below). The next attempt to define a specification was to fit within 4 SDCM. The result was a specification that may be accepted where quality of light is unnecessary (outdoor applications, etc.) but still unacceptable for most applications. A closer examination to how the human eye works revealed an interesting phenomenon that the eye is less sensitive to CCT changes, but more sensitive to DUV changes (pink or green hues). The end result is a specification that is ~2 SDCM in CCT (along the black body line), but much less than 2 SDCM in DUV (see plots below).


XSM technology c/w pc LED array + collimator modules

• Reliability / ruggedness (often 60-80 small die with wire bonds)• Reliability with low temperature operation due to effect of thermal

shocks (above cause)• Colour point inconsistency (no chance to do phosphor tuning)• Depreciation and colour point change over time - effect of higher

phosphor temperatures (close to junction temperature) and degradation of the encapsulant.

• Greater colour point change with changes in ambient temperature (explained in following slide)

• IP 66 not possible• Light distribution uneven over disc and angle caused by LED

binning, “yellow ring” effect + shadowing caused by multiple light points. (Explained in following slides).

• Phosphor is exposed (any grease etc on assembly will result in light loss). Or if front glass used then 8% losses – effects efficiency.


Effect of binning


Effect of temperature


• Phosphor gets hot, hotter than LED• Phosphor output varies with

temperature• Phosphor has variations in particle size,

concentration, layer thickness …

Blue chip varies in wavelength, efficiency and temperature dependency due to production process spread

Phosphor gets hot as heat generated by the phosphor has to be transported through the (hot)

die, submount and heatsink, and cannot be cooled through the (thermally isolating) lens

Red efficiency cliff

XSM technology c/w separated phosphor modules

• Other separated phosphor modules, with different thermal designs, are bigger (beyond pro-rata for lumen package). Similarly the heat sink requirements.

• Usage of plastic front plates: thermally inferior (affects phosphor degradation) + yellowing

• With other designs IP 66 is not possible• Phosphor deposition method will not allow same colour

point consistency part to part or in time• Also connected with phosphor deposition, unevenness

can cause uniformity issues across beam (see next slide)


Aspect Quantification C/W low voltage halogen C/W MR16 Compact Metal halide C/W Retrofit LED solutions

Quality of light

• CRI 80+ / 97• 3 SDCM• Perfectly uniform

beam (flux and colourpoint)

+• Halogen has better CRI than 80

series version and approx equal to 90 series version, but lower uniformity in beam and colour changes between brands

+• CMH has equal or lower CRI, lower

R9 and lower uniformity in beam and colour point consistency

+• Equal or lower CRI, lower R9, lower

uniformity in beam and worse colour point consistency

Choice of CCT

• 2700K, 3000K,4000K

+• Not such wide choice: 2700K not

available unless via dimming nor 4000K without filters – both strongly decrease efficacy

+• Not such wide choice; 2700K

not available

+• Not such wide choice; 2700K rarely

available

Amount of light

• 340-1000lm depending on drive current / CCT

• Over 1500cd peak I with 40°beam realized

/• Comparable with 20 to 50W low

voltage halogen

(-)• CMH has higher luminous flux, but

output not as well controlled and 50% depreciation at 6khrs (maintained illuminance!)

+• Less light (true retrofits, ie similar size

to conventional equivalents, are limited in wattage to about 7W)

Initial Price • Typical luminaire price: €100

-• Typical halogen luminaire price:

€20

-• Typical CMH luminaire price: €60

-• Typical retrofit LED luminaire

price: €40

Life • 50khrs +• 1-4khrs

+• 12khrs

+• 20-35khrs and no future

proof designEfficacy • 45-55lm/W (increases

with decreasing current CCT)

+• Up to 20lm/W

(-)• CMH in MR16 format is around

50lm/W – but see note above about control and depreciation

/• Comparable efficacy

(or slightly lower)

Comments • 2 year payback possible c/w low voltage halogen with maintenance and energy savings

• Halogen has some UV / IR• Similar size• Less uniform beam

• Run-up time, high voltages, inrush current (lamps / mcb)

• Unsaturated rendering of reddish colours

• No dimming• Some UV / IR• Similar size

With collimated LEDs tighter beams are possible in smaller luminaires.

Shorter payback if light technical compromise is acceptable

Similar size Less uniform beam

XSM technology c/w halogen, CMH and LED MR16 lamps


Uniform beam: XSM c/w halogen and LED MR16 lamps

Alpha LED / XicatoTypical Halogen LED Array

Halogen lamps and LED arrays can suffer from local variations of light over a surface due to non-uniform illuminance of the source. The Xicato module has a uniform

(Lambertian) emitting disk as source, which is reflected in the beam.

XSM technology c/w CMH and CFL

• Outside of MR16 formats of these lamp types it is not fully logical to make benchmarking comparisons as the higher fluxes of the former and larger sizes of the latter result in different luminaire and application areas. As XSM lumen packages increase so downlighting possibilities will increase and these comparisons will become more relevant.

• Currently lumen packages of the traditional technologies can be higher, luminaire efficacies are on a par, light quality favours XSM (mostly because of its colour point stability) and life favours XSM (see next slide for lumen maintenance comparison).


Lumen maintenance comparisons: XSM, CMH and CFL


CMH, typical

CFL, typical

XSM

Full Technical Analysis

full technical analysis - alphaled · projection lighting - 30 sept, 2009 • voltage drop is a...

Documents