Abstract

In this paper, the advantages of using Cree and Cree product features will be reviewed, where this included Cree HP and multi-chip Lighting class LED. Meanwhile, suggested LED components for various application segments in general illumination will also be presented in this paper.

Introduction: LED in lighting market

Lighting-class LEDs are now available in Cree that diver the brightness, efficacy, lifetime, color temperatures, and white-point stability required for general illumination. As a result, these LEDs are being designed into most general lighting applications, including roadway, parking area, and indoor directional lighting. LED-based luminaries reduce total-cost-of-ownership (TCO) in these applications through maintenance avoidance (since LEDs last much longer than traditional lamps) and reduced energy costs.

Nowadays, there are over 20 billion light fixtures using incandescent, halogen, or fluorescent lamps worldwide. Many of these fixtures are being used for directional light applications but are based on lamps that put out light in all directions. The United States Department of Energy (DOE) states that recessed downlights are the most common installed luminaries type in new residential construction. In addition, the DOE reports that downlights using non-reflector lamps are typically only 50% efficient, meaning half the light produced by the lamp is wasted inside the fixture.

In contrast, lighting-class LEDs offer efficient, directional light that lasts at least 50,000 hours. Indoor luminaries designed to take advantage of all the benefits of lighting-class LEDs can:

a) Exceed the efficacy of any incandescent and halogen luminaries

b) Match the performance of even the best CFL (compact fluorescent) downlights.

c) A lifetime five to fifty times longer than these lamps before maintenance.

d) Reduce the environmental impact of light: no mercury, less power-plant pollution, and less landfill waste.

e) Instant ON/OFF without delay time compare with HID and fluorescent tube.

f) Low voltage turn on provide safer operation.

g) Small form factor

In fact, LED has a lot of advantages over traditional light source, currently the possible application areas for LED lighting include:

a)     General lighting including, indoor, outdoor and portable lighting

b)     Signage and Indication

c)      Backlighting and video screen

d)     Automotive, forward and directional lighting

e)     Advertisement and retail lighting

Table 1 summarize the Cree high power LED and its electrical and optics characteristic. Up to May 2010, XRE, XPE and MCE have accepted by the Energy star SSL lumen depreciation requirement (LM-80). Meanwhile, XPE is a UL recognized which can be safely used in SSL application

Table 1 Cree HP Led product summary

In the following sections, the focus application area (general illumination) of lighting class LED, MPL, MCE, XP and MX6 will be presented.

Application of Cree Lighting Class LED

MPL LED

Lighting class MPL-EZW LED is a 24 die multiple chip LED which has 3 string and 8 LED chips series. Maximum lumen output can go up to 1350 lumen at 250mA. XLamp MP-L EasyWhite eliminates traditional chromaticity binning and maximizes lumen density, enabling luminaire and bulb retrofit manufacturers to deliver consistent color and required light output to the target end user. XLamp MP-L EasyWhite LEDs reduce LED-to-LED color variation to within a 4-step MacAdams ellipse around the desired color temperature, which is 75% smaller than the total area of the corresponding ANSI C78.377 color region.

Because of its color temperature as well as its high lumen output, it can reduce total system cost and production cost. It is a perfect choice for indoor lighting application such as in table 2.

Table 2. MPL EZW focus application segment

Fig. 1 EasyWhite color temperature

MCE LED

MCE is another multiple chip LED from Cree, compare with MPL LED, it is smaller in size (7.0mm x 9.0mm) and less LED die in its package. In MCE LED, there are 4 individually accessed LED chips which can drive up to 700mA. Maximum lumen can reach 790 lumen when the driving current goes up to 700mA. Because of easywhite CCT and its system cost reduction features similar to MPL LED, it is a perfect choice on indoor lighting. Its light output is equivalent to a 20W 30W MR types halogen lamp.

Fig.2 Comparison of MCE and MR16 halogen lamp

Because of its high lumen output, ANSI sub bin features and uniformity light output, therefore, MCE LED can also be applied in outdoor lighting such as roadway lighting. In additional, because it is also a good choice of MR16 lamp halogen lamp replacement, thus, it can also be applied in landscape lighting as well.

Table 3. MCE LED target application

XP LED (XPG and XPE LED)

XPG and XPE LED is a single die LED which is able to drive up to 1500mA and 1000mA respectively. It can deliver 493 lumen at 1500mA which is 93lm/W and 291 lumen at 1000mA which is 87lm/W. High efficacy makes both LED suitable on various lighting application including outdoor, indoor and portable lighting application.

XP LED is an excellent choice of outdoor, indoor and portable lighting application, compare with XR LED, it has unlimited floor life which is an advantage improve the product quality.

Table 4a XPG LED target application

Table 4b XPE LED target application

For XP LED in outdoor lighting application, designer can consider using outdoor white which has higher lumen/Watt. CCT of Outdoor white is range from 4000K to 5300K which target to replace HID lamp.

Fig.3 ANSI Outdoor White

MX6 LED

MX6 is a lighting class LED which target for indoor lighting application, It has a low forward voltage drop, better color consistency, and isolated thermal path compare with its market competition. A better color quality and consistency makes MX6 LED a good light source for linear lighting and fluorescent tube replacement.

Meanwhile, most recent reliability figures introduces that Cree MX6 LED is able to increase the driving current up to 1000mA. It provides around 250% of lumen output when it increase the driving current upt o 1000mA.

Table 5 MX6 target application

For linear lighting in indoor lighting application, other LED which can be used in in such application includes high brightness LED such as CLA1A and CLP6B. Those LEDs can provide excellent uniformity and color quality.

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