A19 Reference Design

Application Note
Cree® XLamp® MX-6 LED
A19 Lamp Reference Design
Table of Contents
Introduction
Introduction..................................................................................... 1
Like all replacement bulbs, LED-based A-19 retrofit lamps pose
Design approach/objectives.......................................................... 2
many engineering challenges. Among these are delivering a
The 6-step methodology................................................................. 2
light distribution and chromatic profile equivalent or superior to
1. Define lighting requirements................................................. 2
comparable incandescent lamps while dissipating the thermal
2. Define design goals............................................................... 3
load of LEDs delivering several hundred lumens.
3. Estimate efficiencies of the optical, thermal & electrical
systems.................................................................................. 4
4. Calculate the number of LEDs.............................................. 6
5. Consider all design possibilities........................................... 8
6. Complete the final steps: implementation and analysis..... 8
Conclusions................................................................................... 15
CLD-AP78 rev 0D
1st page
This application note describes the design of a 40-W equivalent
A19 retrofit lamp based on the Cree XLamp® MX-6 family of
LEDs. This lamp has been designed for the Asian market and
associated emerging national standards. It is a cool white bulb
with a lower Color Rendering Index (CRI) which also makes it a
device not suitable for current European or American national
standards. We created two versions of the lamp, one with the
MX-6 package, having 4 LEDs connected in parallel, and one
with the MX-6S package, having 4 LEDs connected in series,
providing an opportunity to compare the performance of two
physically identical but electrically different LED packages and
www.cree.com/Xlamp
associated drivers.
Reliance on any of the information provided in this Application Note is at the user’s sole risk. Cree and its affiliates make no warranties or representations about, nor assume
any liability with respect to, the information in this document or any LED-based lamp or luminaire made in accordance with this reference design, including without limitation
that the lamps or luminaires will not infringe the intellectual property rights of Cree or a third party. Luminaire manufacturers who base product designs in whole or part on
any Cree Application Note or Reference Design are solely responsible for the compliance of their products with all applicable laws and industry requirements.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are
registered trademarks and the Cree logo is a trademark of Cree, Inc. Other trademarks, product and company names are the property of their respective
owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product specifications, please see the data
sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
Cree, Inc.
4600 Silicon Drive
Durham, NC 27703
USA Tel: +1.919.313.5300
1
XLamp ® MX-6 LED A19 Lamp Reference Design
Design approach/objectives
In the “LED Luminaire Design Guide” Cree advocates a 6-step framework for creating LED luminaires. All Cree reference designs use this
framework, and the design guide’s summary table is reproduced below.
Table 1: Cree 6-step framework
Step
Explanation
1. Define lighting requirements
•
The design goals can be based either on an existing fixture or on the application’s lighting requirements.
2. Define design goals
•
•
Specify design goals, which will be based on the application’s lighting requirements.
Specify any other goals that will influence the design, such as special optical or environmental requirements.
3. Estimate efficiencies of the optical, thermal &
electrical systems
•
•
•
Design goals will place constraints on the optical, thermal and electrical systems.
Good estimations of efficiencies of each system can be made based on these constraints.
The combination of lighting goals and system effiiciencies will drive the number of LEDs needed in the
luminaire.
4. Calculate the number of LEDs needed
•
Based on the design goals and estimated losses, the designer can calculate the number of LEDs to meet the
design goals.
5. Consider all design possibilities and choose
the best
•
•
With any design, there are many ways to achieve the goals.
LED lighting is a new field; assumptions that work for conventional lighting sources may not apply.
6. Complete final steps
•
•
•
•
•
Complete circuit board layout.
Test design choices by building a prototype luminaire.
Make sure the design achieves all the design goals.
Use the prototype to further refine the luminaire design.
Record observations and ideas for improvement.
The 6-step methodology
The goal of this reference design is a 40-W-equivalent, A19 retrofit lamp. This design uses Cree XLamp MX-6 family LEDs combined with
open-market tooling, optics and drivers and focuses on creating a snow-cone-type A19 retrofit lamp.
1. Define lighting requirements
The table below lists important characteristics to consider for the design of the MR16 in this reference design.
Table 2: Ranked design criteria for a 40-W, A19 retrofit lamp
Importance
Critical
Characteristics
Units
Luminous flux
lumens (lm)
Efficacy
lumens per watt (lm/W)
Illuminance distribution
footcandles (fc)
Color uniformity
Form factor
Important
Price
$
Lifetime
hours
Operating temperatures
°C
Operating humidity
% RH
Correlated Color Temperature (CCT)
K
CRI
100-point scale
Manufacturability
Ease of installation
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
2
XLamp ® MX-6 LED A19 Lamp Reference Design
Because this reference design targets the Asian market, we benchmarked the Korean KSC7651 and Japanese JIS C 7501 standards,
excerpted in Table 3 and Table 4 below.
From the Korean standard:
Table 3: Korean KSC7651 standard excerpt
CCT (K)
CCT Tolerance
CRI
6500
7040-6020
70
5700
6020-5310
70
5000
5310-4745
70
4500
4746-4260
70
4000
4260-3710
70
3500
3710-3220
70
3000
3220-2870
70
2700
2870-2580
70
From the Japanese standard:
Table 4: Japanese JIS C 7501 excerpt
Power
Luminous flux
25 W
230 lm
40 W
440 lm
50 W
600 lm
60 W
760 lm
75 W
1000 lm
100 W
1430 lm
2. Define design goals
The design goals for this project:
Table 5: Design goals
Characteristic
Light output
Power
Unit
Minimum Goal
Target Goal
lm
440
> 440
W
< 10
8
Luminaire efficacy
lm/W
> 45
56
Lifetime
Hours
50,000
50,000
K
5000
5000
CCT
CRI
Power factor
Maximum ambient temperature
°C
70
> 70
0.55
> 0.7
30
40
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
3
XLamp ® MX-6 LED A19 Lamp Reference Design
3. Estimate efficiencies of the optical, thermal & electrical systems
LED Component Performance
Figure 1-MX6A
Figure 1-MX6S
This reference design is based on Cree’s MX-6 product family. The MX-6 LED has a variety of efficacies depending on color temperature,
bin, and drive conditions. The non-directional light output of the MX-6 is ideal for an A19 lamp design; a snow-cone diffuser can further
improve lighting uniformity and give the lamp an even lighting effect. Considering overall system efficiency and cost, we based designs on
the MX-6 and groups\XLamp\Data
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component and illustrate
the
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ge 2
This chart is on page 2
Figure 2
Figure 1: Binning options for MX-6 (left) and MX-6S (right)
Thermal Requirements
Despite LED’s inherent efficacy advantage over conventional incandescent or fluorescent lighting,
up to 75% of the input power is converted to heat. This heat must be dissipated (conducted)
efficiently to ensure LED lumen maintenance and reliability. For a 40-W equivalent A19 retrofit
lamp, we estimate the total power to be dissipated to be around 8 W. For this power level, there
are many existing thermal solutions from which to choose. For this reference design, Cree chose
an existing well-designed cast aluminum heat sink with good workmanship.1 Our simulation and
actual test results confirmed this as a good choice for this retrofit lamp.
Figure 2: Aluminum heat sink
Cree’s thermal simulation2 of the MX-6 design with an input power of 8 W resulted in a solder point temperature estimate of ~60 °C. This
is in reasonable agreement with the actual measurement of 68 °C from our thermocouple steady-state measurement. Figure 3 shows
the thermal simulation of the solder point temperature. Figure 4 shows the thermal simulation of the airflow, in the form of convection
1
2
The heat sink is from a How Nice Optoelectronics A19 bulb
Cree used NIKA EFD Pro with Pro Engineering Wildfire
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
4
Figure 3
Figure 4
XLamp ® MX-6 LED A19 Lamp Reference Design
currents, around the MX-6 A19 lamp. We did not simulate both versions since we do not expect a significant difference in thermal
performance for the MX-6S LED implementation.
Figure 3: Thermal simulation of temperature of MX-6 A19
Figure 5Figure 4: Thermal simulation of airflow around MX-6 A19
Drive Electronics
The choice of driver for an A19 retrofit lamp is constrained by the need for the driver to fit within the limited space of the A19 housing. We
used two drivers for the A19 lamp designs, a low-voltage, high-current driver for the MX-6 lamp and a low-current, high-voltage driver for
the MX-6S lamp. Because of the high-voltage nature of MX-6S LED, its driver is expected to have higher efficiency. For safety concerns,
we limited our design to isolated power designs.
Figure 5: General circuit design for MX-6 driver
Both power supplies use a flyback design. The power factor for each of these drivers is above 0.5, and both were designed to fit in the
form factor of an A19 lamp.
Figure 6 shows that the driver for the MX-6S lamp is appreciably smaller than the driver for the MX-6 lamp.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
5
XLamp ® MX-6 LED A19 Lamp Reference Design
Figure 6-MX-6S driver
Figure 6-MX6A driver
Figure 7
Figure 6: Drivers for MX-6 (left) and MX-6S (right)
Secondary Optics
Uniformly distributed lighting is a key requirement for an LED-based A19 retrofit lamp. The secondary optics must diffuse the light from
the LED and distribute it evenly and uniformly, giving an effect of a diffuse source rather than a bright hot spot. Good secondary optics
contribute to both brightness and color uniformity without a great sacrifice in optical efficiency. The three sample diffusing domes we
evaluated all were 85% efficient. That is, there was a 15% loss of signal when using a diffusing dome. Figure 7 shows an example of a
diffuser used in an LED lamp to achieve a uniform lighting effect.
Figure 7: Diffuser example
4. Calculate the number of LEDs
We used Cree’s Product Characterization Tool (PCT) to estimate the number of LEDs to be used, specifying parameters such as light
output and limitations of driver and optical efficiency. Due to the different LED arrangements in the MX-6 and MX-6S packages, we paid
special attention to the bin from which we selected the LEDs. We wanted to compare the two lamps and, because the binning conditions
are different, the power levels are also different.
As shown in Figure 8 and Figure 9, we chose to use four MX-6 LEDs from the Q5 flux bin (order code MX6ASWT-A1-2B0-Q5) and four
MX‑6S LEDs from the R4 flux bin (order code MX6SWT-A1-3C0-R4) for the two A19 retrofit lamps.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
6
XLamp ® MX-6 LED A19 Lamp Reference Design
LED System Comparison Report
1
System:
450
Target Lumens :
$
Price
SYS # LED SYS lm tot
0.100
0.110
0.120
0.130
0.140
0.150
0.160
0.170
0.180
0.190
0.200
0.210
0.220
0.230
0.240
0.250
0.260
0.270
0.280
0.290
0.300
0.350
0.400
0.450
0.500
0.550
0.600
0.650
0.700
16
15
14
13
12
11
11
10
10
9
9
8
8
8
7
7
7
7
7
6
6
5
5
5
4
4
4
4
3
Flux
Model
Tsp (ºC)
Q5 [107]
462.3
473.6
479.3
479.5
474
463.1
491.6
472.6
498
471.1
493.7
458.7
478.5
498.1
453
469.9
486.7
503.3
519.8
459.6
473.7
451.4
505.8
557.7
486
523.9
559.9
594.2
469.9
75%
Electrical Efficiency:
LED 2
Cree XLamp MX-6 {CW/WW}
Current (A)
Model
85%
Optical Efficiency:
LED 1
SYS W
5.92
6.15
6.31
6.39
6.39
6.32
6.78
6.59
7.03
6.72
7.11
6.68
7.04
7.4
6.8
7.12
7.45
7.78
8.11
7.24
7.52
7.5
8.77
10.09
9.15
10.25
11.37
12.52
10.25
Flux
70
LED Vf
2.78
2.8
2.82
2.83
2.85
2.87
2.89
2.91
2.93
2.95
2.96
2.98
3
3.02
3.03
3.05
3.07
3.09
3.1
3.12
3.14
3.21
3.29
3.36
3.43
3.49
3.55
3.61
3.66
Model
Cree XLamp MX-6 {CW/WW}
Tsp (ºC)
Q4 [100]
$
Price
SYS # LED SYS lm tot
17
16
15
14
13
12
11
11
10
10
9
9
9
8
8
8
7
7
7
7
7
6
5
5
4
4
4
4
4
LED 3
459
472.2
479.9
482.6
479.9
472.2
459.5
485.8
465.4
489.2
461.4
482.3
503.1
465.5
483.8
501.9
454.8
470.4
485.8
501.1
516.5
506.2
472.7
521.2
454.2
489.6
523.3
555.4
585.6
70
Price
SYS W
6.29
6.56
6.76
6.88
6.92
6.89
6.78
7.25
7.03
7.46
7.11
7.51
7.92
7.4
7.77
8.14
7.45
7.78
8.11
8.44
8.78
9
8.77
10.09
9.15
10.25
11.37
12.52
13.67
(none)
Flux
Tj (ºC)
$
25
-
LED Vf
2.78
2.8
2.82
2.83
2.85
2.87
2.89
2.91
2.93
2.95
2.96
2.98
3
3.02
3.03
3.05
3.07
3.09
3.1
3.12
3.14
3.21
3.29
3.36
3.43
3.49
3.55
3.61
3.66
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LED System Comparison Report
8: Cree’s
PCT
with MX-6
This document is provided for informational purposes only and is not a warranty or Figure
a specification.
For product
specifications,
please data
see the data sheets available at www.cree.com.
Copyright © 2009-2011 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree, the Cree logo and XLamp are registered trademarks of Cree, Inc.
1
System:
450
Target Lumens :
Current (A)
LED 1
Model
Flux
R4 [130]
75%
Electrical Efficiency:
LED 2
Model
Cree XLamp MX-6S {CW/WW}
$
Price
SYS # LED SYS lm tot
85%
Optical Efficiency:
Tsp (ºC)
70
Flux
LED 3
Model
Cree XLamp MX-6S {CW/WW}
R3 [122]
$
Price
SYS # LED SYS lm tot
Tsp (ºC)
70
(none)
Flux
Price
Tj (ºC)
$
25
-
SYS W
LED Vf
SYS W
LED Vf
0.020
13
467.7
5.85
16.86
14
472.7
6.3
16.86
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0.030
9
466.8
6.28
17.44
10
486.7
6.97
17.44
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0.040
7
469.7
6.71
17.98
8
503.8
7.67
17.98
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0.050
6
490
7.4
18.49
6
459.9
7.4
18.49
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0.060
5
477.9
7.59
18.98
6
538.2
9.11
18.98
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0.070
5
544.2
9.07
19.44
5
510.7
9.07
19.44
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0.080
4
485.7
8.47
19.86
4
455.8
8.47
19.86
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0.090
4
533.6
9.73
20.26
4
500.7
9.73
20.26
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0.100
4
578.7
11
20.63
4
543.1
11
20.63
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0.110
3
465.9
9.23
20.97
4
583
12.3
20.97
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0.120
3
496
10.21
21.28
3
465.5
10.21
21.28
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0.130
3
524.2
11.21
21.56
3
491.9
11.21
21.56
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0.140
3
550.5
12.22
21.82
3
516.7
12.22
21.82
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0.150
3
574.9
13.23
22.04
3
539.5
13.23
22.04
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0.160
3
597.6
14.23
22.24
3
560.8
14.23
22.24
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0.170
3
618.3
15.24
22.41
3
580.3
15.24
22.41
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0.180
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MX-6S data
0.200
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0.210
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Copyright
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to change without
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registered #N/A
trademarks and
the Cree logo
is a trademark of
Cree, Inc.
Other trademarks,
product
and company
names are#N/A
the property of their
respective owners
imply specific
product and/or vendor
0.250
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specifications,
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sheets available
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information,
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#N/A
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#N/A
7
0.270
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
0.280
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
XLamp ® MX-6 LED A19 Lamp Reference Design
Table 6 shows the characteristics of the MX-6 LEDs selected for this A19 reference design.
Table 6: MX-6 and MX-6S characteristics
Component
Bin
Light Output
Test Current
Vf at
Test Current
Power
Efficacy
MX-6
Q5
107 lm
300 mA
3.3 V
0.99 W
108.7 lm/W
MX-6S
R4
130 lm
60 mA
20 V
1.2 W
108.3 lm/W
With both designs having the same number of LEDs, efficacy and light emission pattern, this design effort is a good comparison of the
two different driver-design efficiencies. The results can serve as a reference on MX-6 and MX-6S performance in overall luminaire designs.
5. Consider all design possibilities
Due to the vast quantity of A19 retrofit designs and parts available in the market, our team tried a number of combinations of available
heat sinks, optics, and driver solutions. We finally chose to use an A19 kit from Shenzhen How Nice Optoelectronics Co., Ltd. that includes
a heat sink, metal core printed circuit board (MCPCB), E27 screw base, and optical diffuser.3 The diffuser in this kit has a measured
efficiency of 85%. Secondary-optics efficiency can reach 90%; however, since the primary function of this diffuser is to mix light and
even out any hot spots, more internal mixing would cause a decrease in efficiency. We believe this optical efficiency is acceptable in this
reference design. We believe that increased efficiency is possible in a custom design.
We chose drivers from TXM Power Co. Ltd. and Gain High Ltd. The general specifications are shown in Table 7. The specifications were
rather straightforward for the low-voltage design; the current is determined by the PCT calculation and the voltage is greater than the
forward voltage of four LEDs connected in series. For the high-voltage design, we did not connect all four MX-6S LEDs in series; we made
two strings of two LEDs connected in series then connected the two strings in parallel. The LED voltage of the MX-6S LEDs connected
this way is about 40 V.
Table 7: Driver specifications
Driver Design
LED
High current, low voltage
High voltage, low current
Arrangement
Output Voltage
Output Current
Vendor
MX-6
4 LEDs in series
13.7 V
450 mA
TXM Power Co. Ltd.
MX-6S
2 parallel strings of 2
LEDs in series
38.2 V
165 mA
Gain High Ltd.
6. Complete the final steps: implementation and analysis
The methodology described above determined a suitable combination of MX-6 LEDs, components and drive conditions. This section
describes how we assembled two A19 retrofit lamps and compares their performance with our targets for a 40‑W equivalent A19 retrofit
lamp for the Asian market. This section also includes a comparison of the driving schemes for the two reference designs.
Prototyping Details
1. We verified the component dimensions to insure a correct fit.
2. Following the recommendations for the XLamp MX family LEDs, we reflow soldered the LEDs onto the MCPCB with an appropriate
solder paste and reflow profile. We cleaned the flux residue with isopropyl alcohol.
3
Kit model HLS-F60
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
8
XLamp ® MX-6 LED A19 Lamp Reference Design
3. We applied a thin layer of thermal conductive compound to the back of MCPCB and secured it to the heat sink with the screws
provided.
4. We inserted the driver into the lamp housing, fed the DC output wires through the thru-hole and soldered them to the corresponding
terminal pads on the MCPCB.
Figure 10 components
Figure 10 completed A19
5. We soldered the driver input wires to the E27 base wires’ power connection. We tested the connection by applying power to the E27
base and checked that the LEDs were lit.
6. After the functional check, we assembled the lamp housing and the E27 base. This kit uses a snap-in design. Other kit designs may
vary.
7. We screwed on the diffuser cap.
8. We performed final testing.
Figure 10: Assembly of components to become an A19 retrofit lamp
Results
Thermal Results
Cree verified that the thermal dissipation performance of the heat sink aligns with our simulation. As shown in Figure 11, a thermocouple
was secured to an LED with Arctic Silver thermal epoxy to measure the solder point temperature. The steady-state solder point temperature
of 68 °C shown in Figure 12 demonstrates that the thermal housing is sufficient for this design. An infrared thermal image of the lamp at
steady state, shown in Figure 13, also verified the temperature is within our design estimate.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
9
Figure 13
XLamp ® MX-6 LED A19 Lamp Reference Design
Figure 11: Thermocouple attached to MX-6
LED
Figure 12: MX-6 A19 solder-point temperature measurement
Figure 13: Steady-state
infrared thermal image of
MX-6 A19 lamp
Based on the measured solder-point temperature (TSP), the operating wattage of the LED and the typical thermal resistance of 5 °C/W for
the MX-6 LED, the resulting junction temperature (TJ) was calculated to be 78 °C.
TJ = TSP + (LED power*LED thermal resistance)
TJ = 68 °C + 2 W * 5 °C/W
TJ = 78 °C
Based on Cree’s LM-80 testing of the MX-6 LED and using industry standard extrapolation methods, Cree expects this A19 lamp to achieve
a lifetime of at least 50,000 hours.4
Visual Performance
Figure 14 is a plot of the luminous distribution in the 0 to 150 degree zone for the MX-6 snow-cone retrofit lamp along with the distribution
for a typical compact fluorescent lamp (CFL) and an incandescent lamp. By design, the snow‑cone lamp is more “forward directing” than
the omnidirectional CFL and incandescent lamps. The luminous distribution curve in Figure 14 also shows a smooth change over the
viewing angle, giving an evenly lighted surface. The full width half medium (FWHM) of the distribution is about 140 degrees. We believe
this is acceptable for a lamp that is mounted upside down in many ceiling fixture applications, in which lighting the ceiling is not a critical
requirement. This design also gives an even color distribution, as shown in the CCT distribution plot in Figure 15 and the photograph in
Figure 16. In summary, this design meets the optical requirement targets for this design.
4
After 50,000 hours of operation, in a well designed system, the LED will still deliver at least 70% of its initial luminous flux.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
10
XLamp ® MX-6 LED A19 Lamp Reference Design
Figure 14
Figure 15
Figure 14: Normalized luminous distribution comparison
Figure 15: CCT uniformity comparison
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
11
XLamp ® MX-6 LED A19 Lamp Reference Design
Figure 16
Figure 16: Lighting effect of MX-6 A19 retrofit lamp on a white wall background
Optic results
Cree tested both designs for lumen output in a 500-mm integrating sphere.5 We waited ten minutes to allow the lamps to reach steadystate before measurement. Table 8 summarizes the test results. We note that the light output from the MX-6 lamp is slightly below the
450-lm target, despite the unit producing 450 lm in an instant-on measurement. The thermal lumen depreciation at elevated temperatures
can be improved by a better heat-sink design. Another solution is to increase the output current to 485 mA; however, due to the time
required to incorporate a new driver, we did not pursue this option because the MX-6S design met the light output requirement. Another
reason for the shortcoming is the actual diffuser efficiency is 85% rather than 90% in the PCT estimate.
5
Measured in an integrating sphere at Cree’s facility in Santa Barbara, CA.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
12
XLamp ® MX-6 LED A19 Lamp Reference Design
Table 8: MX-6 A19 retrofit lamp optical results
Characteristic
Unit
MA-6A
MA-6S
Light output (10 min on time)
lm
410
451
Current
mA
462
165
Power
W
8.6
7.9
Efficacy
lm/W
47.7
57
CCT
K
5951
4922
Lifetime
hours
50,000
50,000
71.4
68.9
CRI
Compared to the MX-6 lamp, the MX-6S lamp offers advantages in light output, current and efficacy. In addition, the high-voltage MX-6S
lamp can operate with smaller and higher efficiency drivers.
All the benefits of using the MX-6S LED are not reflected in PCT data. In an article in the February, 2011, issue of LEDs Magazine, Matthew
Reynolds of National Semiconductor shows that using high-voltage LEDs results in lower operating temperatures of driver electronics,
presenting the possibility of drivers that are more efficient and reliable.6 In the PCT analysis in Figure 17, a 6% increase in driver efficiency,
from 80% to 85%, delivers an equivalent 6% improvement in efficacy.
Improvement Opportunities
We estimated the results of one potential improvement in the MX-6S A19 retrofit lamp. The PCT was configured to use the data measured
for the MX-6S lamp: target lumens of 450, 85% optical efficiency, 80% electrical efficiency and TSP of 68 °C. Using the 8.6-W power level
of the MX-6 lamp to utilize the “spare” power available to the MX-6S LED, we extrapolated an increase in the lumen output to 525, a 7%
improvement while maintaining the CCT and A19 form factor.
Figure 17 is an estimate of the results of using warm-white MX-6S LEDs to achieve a warmer CCT than that of the cool-white LEDs used in
the design. The figure presents data for warm-white LEDs from the Q5 and Q4 flux bins in comparison to data for the cool-white LED used
in the design. The PCT was again configured to use the data measured for the MX-6S lamp: target lumens of 450, 85% optical efficiency
and 80% electrical efficiency and TSP of 68 °C. The data show that power greater than 10 W is required to achieve 450 lumens. The drive
current must increase to 100 mA for the Q5 LED and to 110 mA for the Q4 LED. The higher TSP for the warm white LEDs reflects one result
of the higher power level. At this power level, the Q4 LED efficacy value drops to 40 lm/W, below the target for this design but possibly
acceptable if color temperature is more important than efficacy.
6
Reynolds, Matthew, “High LED Drive Currents with Low Stack Voltages Create Efficiency Challenges,” LEDs Magazine, February, 2011, pp 53-59.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
13
XLamp ® MX-6 LED A19 Lamp Reference Design
LED System Comparison Report
1
System:
450
Target Lumens :
Current (A)
LED 1
Model
Flux
Tsp (ºC)
68
$
Price
SYS # LED SYS lm tot
Flux
LED 3
Model
Cree XLamp MX-6S {CW/WW} x2
Q5 [107]
$
Price
SYS # LED SYS lm tot
80%
Electrical Efficiency:
LED 2
Model
Cree XLamp MX-6S {CW/WW} x2
R4 [130]
85%
Optical Efficiency:
Tsp (ºC)
80
Flux
Cree XLamp MX-6S {CW/WW} x2
Q4 [100]
Tsp (ºC)
85
$
Price
SYS # LED SYS lm tot
SYS W
SYS lm/W
SYS W
SYS lm/W
SYS W
SYS lm/W
0.020
14
506.7
5.92
85.6
16
459.5
6.67
68.9
18
475.6
7.45
63.8
0.030
10
521.8
6.55
79.6
12
496.7
7.76
64
12
457
7.71
59.3
0.040
8
540.1
7.21
74.9
10
535.5
8.89
60.2
10
492.6
8.84
55.7
0.050
6
493
6.95
70.9
8
521.4
9.15
57
8
479.6
9.1
52.7
0.060
6
577
8.56
67.4
6
457.6
8.45
54.2
8
561.3
11.21
50.1
0.070
6
657
10.22
64.3
6
521
10.1
51.6
6
479.2
10.05
47.7
0.080
4
488.7
7.96
61.4
6
581.2
11.8
49.3
6
534.5
11.74
45.5
0.090
4
536.9
9.14
58.8
6
638.4
13.54
47.1
6
587.1
13.47
43.6
0.100
4
582.3
10.33
56.3
4
461.5
10.21
45.2
6
636.6
15.25
41.8
0.110
4
625.1
11.55
54.1
4
495.4
11.42
43.4
4
455.5
11.37
40.1
0.120
4
665.5
12.79
52
4
527.3
12.65
41.7
4
484.8
12.59
38.5
0.130
4
703.3
14.04
50.1
4
557.2
13.89
40.1
4
512.3
13.82
37.1
0.140
4
738.7
15.3
48.3
4
585.1
15.13
38.7
4
537.9
15.06
35.7
0.150
4
771.4
16.56
46.6
4
610.9
16.38
37.3
4
561.6
16.31
34.4
0.160
4
801.9
17.82
45
4
635
17.63
36
4
583.7
17.55
33.3
0.170
4
829.7
19.08
43.5
4
656.9
18.88
34.8
4
603.8
18.79
32.1
0.180
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
0.190
#N/A
#N/A
#N/A
#N/A
#N/APCT data
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
Figure 17:
for warm#N/A
white MX-6S
LEDs
0.200
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
0.210
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
Driver-Circuit Comparison
0.220
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
0.230
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
We employed two driver circuit designs for the MX-6 LEDs in this reference design. Table 9 is a summary of the results. They
are both
0.240
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
primary
feedback
flyback
designs
accuracy
loss#N/A
are very #N/A
similar. The power
the MX-6S
driver is
0.250
#N/A
#N/A
#N/A and current
#N/A
#N/Aand inherent
#N/A
#N/A required
#N/A to run#N/A
#N/A
0.260
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
about 9% less than that for the MX-6 driver, as shown in the efficiency difference. There are two main losses in the MX-6 driver design
0.270
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
0.280
#N/A
#N/A design:
#N/Aa large#N/A
#N/A
#N/A
#N/A
compared
to the MX-6S
voltage drop#N/A
and a high
current #N/A
loss. The #N/A
large voltage #N/A
differential
can be viewed
as#N/A
similar to
0.300
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
transformer
conversion
efficiency:
the #N/A
larger the differential,
the
larger the
loss. For
the high current
loss, #N/A
the output#N/A
power loss
can be
0.350
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
stated simply as:
This document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com.
Copyright © 2009-2011 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree, the Cree logo and XLamp are registered trademarks of Cree, Inc.
2
loss
P
=I xR
where R = total internal resistance
I = output current
When the output current increases, power loss also increases. This is a simple explanation of the efficiency difference and the reason
for creating a high-voltage version of the MX-6 component, thereby presenting an opportunity to optimize other system components to
increase overall system efficiency.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
14
XLamp ® MX-6 LED A19 Lamp Reference Design
Table 9: MX-6 and MX-6S LED-driver results comparison
Characteristic
4 MX-6 LEDs in Series
4 MX-6S LEDs in 2 Parallel
Strings of 2 LEDs in Series
Input voltage
220 VAC
220 VAC
Input power
8.6 W
7.9 W
Output current
462 mA
165 mA
Output voltage
13.7 V
38.2 V
Power factor
0.58
0.55
Efficiency
73.6%
79.8%
Current ripple
38%
12%
Conclusions
In this reference design, we accomplished the goal to design a 40-W equivalent, A19 retrofit lamp for the Asian market using the Cree
XLamp MX-6 and MX-6S high-power LEDs. Using four MX-6 and MX-6S LEDs, the snow-cone lamps are comparable to a traditional A19
incandescent lamp but use 80% less power and offer a lifetime of more than 50,000 hours.
Our tests showed that the components used in this design satisfied most of our requirements and provide reasonable performance for a
reference design. Improvement in every aspect of the design can be made by applying resources to optimize each of the optical, thermal
and electrical components. Moreover, comparing the MX-6 and MX-6S A19 lamps reveals that the MX-6S LED offers the possibility
of reducing other system-component limitations to further increase system efficiency. This is an example of a design that presents
opportunities for enhancement to reach higher performance levels.
Reliance on any of the information provided in this Application Note is at the user’s sole risk. Cree and its affiliates make no warranties or representations about, nor assume any
liability with respect to, the information in this document or any LED-based lamp or luminaire made in accordance with this reference design, including without limitation that
the lamps or luminaires will not infringe the intellectual property rights of Cree or a third party. Luminaire manufacturers who base product designs in whole or part on any Cree
Application Note or Reference Design are solely responsible for the compliance of their products with all applicable laws and industry requirements.
Copyright © 2011-2016 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree® and XLamp® are registered trademarks and the Cree logo is a trademark of
Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. For product
specifications, please see the data sheets available at www.cree.com. For warranty information, please contact Cree Sales at [email protected]
15