8

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.

figure 3: product Characterization tool analysis of a 450-lumen A19 bulb

This analysis shows us many approaches to delivering a 40-w-equivalent value bulb. In considering drive current and

number of leDs, at one end of the spectrum the four mX-6S leDs can present an 85-v, 100-ma load, consume just

under 10 watts of power and deliver just under 50-lm/W efficacy. Six MX-6 LEDs driven at 350 mA deliver over 63 lm/W

while using under 8 watts of power. Four XP-E HEW LEDs, in the R2 flux bin, can deliver equivalent flux at an improved

efficacy of just over 70 lm/W using 6.9 W of power.

The case for using mX-6S leDs is particularly interesting and not well represented in Figure 3 because the high-

voltage LEDs have the potential to allow for higher-efficiency device drivers. In an article in the April 2011 issue of

LEDs Magazine, matt reynolds of National Semiconductor shows through a simple and elegant analysis that the use of

high-voltage leDs allows for lower operating temperatures of supporting driver electronics — capacitors, inductors and

temperatures for capacitors, for example) and more efficient. In our PCT analysis, an increase of 6% efficiency in drive

electronics, from 87% to 93%, delivers an almost 7% improvement in efficacy.

5

Reynolds, Matthew, “High LED Drive Currents with Low Stack Voltages Creat Efficiency Challenges,” LEDs Magazine, February,

2011, pp 53-59.

Figure 3

Compare:

11

13

12

15

2

System:

450

85%

87%

Model

15

Model

14

Model

21

Flux

3

100.0

Flux

6

93.9

Flux

7

114.0

Price

-

$

2.0

55

Price

-

$

2.0

55

Price

-

$

2.0

55

1

1

1

0.100

4

466

9.61

48.5

17

450.5

5.47

82.4

17

477.7

5.28

90.5

0.110

4

500

10.76

46.5

16

464

5.7

81.4

15

460.5

5.17

89.1

0.120

4

532.8

11.91

44.7

15

471

5.86

80.4

14

466.2

5.31

87.8

0.130

4

563.2

13.06

43.1

14

473.2

5.95

79.5

13

466.7

5.23

89.2

0.140

4

591.2

14.25

41.5

13

470.6

6.13

76.8

12

460.8

5.24

87.9

0.150

3

463.2

11.55

40.1

12

463.2

6.07

76.3

11

451

5.18

87.1

0.160

3

481.8

12.45

38.7

11

451

5.94

75.9

11

478.5

5.56

86.1

0.170

3

498.6

13.31

37.5

11

477.4

6.32

75.5

10

461

5.4

85.4

…

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

#N/A

0.300

#N/A

#N/A

#N/A

#N/A

7

506.8

7.64

66.3

6

464.4

5.93

78.3

0.350

#N/A

#N/A

#N/A

#N/A

6

497.4

7.86

63.3

6

532.2

6.97

76.4

0.400

#N/A

#N/A

#N/A

#N/A

5

464

7.7

60.3

5

498

6.72

74.1

0.450

#N/A

#N/A

#N/A

#N/A

5

512

8.79

58.2

5

551

7.64

72.1

0.500

#N/A

#N/A

#N/A

#N/A

5

557.5

10

55.8

4

481.6

6.85

70.3

0.550

#N/A

#N/A

#N/A

#N/A

4

481.2

8.97

53.6

4

520.8

7.63

68.3

0.600

#N/A

#N/A

#N/A

#N/A

4

514.4

9.93

51.8

4

558.8

8.37

66.8

0.650

#N/A

#N/A

#N/A

#N/A

4

546

10.94

49.9

4

594.8

9.1

65.4

0.700

#N/A

#N/A

#N/A

#N/A

4

575.6

11.95

48.2

3

472.2

7.41

63.7

Current Display Range:

LED Multiple

LED Multiple

LED Multiple

Optical Efficiency:

Electrical Efficiency:

Target Lumens :

LED 1

LED 2

LED 3

Cree XLamp MX-6S {CW/WW}

Q4 [100]

Fine

(0.1A - 0.7A)

Cree XLamp MX-6 {CW/WW}

Q3 [93.9]

Cree XLamp XP-E HEW {CW/NW/WW}

R2 [114]

SYS # LED

SYS lm tot

SYS W

SYS lm/W

Tsp (ºC)

Tsp (ºC)

Tsp (ºC)

x1

x1

x1