New LEDs for High-Bay and Outdoor Lighting Applications Offer More for the Money

As lighting engineers look for new ways to simplify their designs for outdoor applications, while at the same time addressing the need for lower cost and higher lumens, LED manufacturers are paying attention. A number of products directed at high-reliability apps have been introduced that deliver a wider range of lumen options, different package styles, and longer life — all contributing to a lower-cost solution.

The total illumination market last year was estimated at $14.5 billion, and it is forecast to grow at a compound annual growth rate (CAGR) of 12 percent through 2017, according to the market research firm Strategies Unlimited. Philips Lumileds and Cree Inc. are cited as examples of two LED manufacturers helping to push the technology into new territory.

Cree is on the fast track when it comes to delivering higher lumens in single-die and array packages. One example is the company's XLamp XM-L2 LEDs, which provides up to 186 lumens/W at 350 mA and 25°C. Based on Cree's SC³ (silicon carbide) technology, the XM-L2 LEDs also are said to double the lumens-per-dollar spec and deliver 20 percent more lumens per watt compared to the original XM-L LED. The upshot: lighting designers can use fewer LEDs at a lower cost, while simplifying their design.

Cree says the XM-L2 LEDs (Figure 1) are designed for very-high-lumen applications such as indoor, high-bay, and outdoor lighting. They are compatible with existing XM-L LED designs and leverage the 5 x 5 mm XM footprint, which means lighting designers can incorporate the XM-L2 LEDs into existing XM LED designs, which shortens the fixture design cycle and improves their time to market.

Figure 1: Cree's XLamp XM-L2 LED delivers up to 186 lumens/W at 350 mA, 25°C.

The XM-L2 LED delivers very high efficacy at high drive currents – 1,198 lumens at 116 lumens/W efficacy at 3 A and 25°C (other key specifications are presented in Table 1). The LED is available in 2,700K to 6,200K color temperatures (characterized at 85°C) and offers minimum CRI options of 80, 85, and 90.

Because the XM-L2 LED is a successor product to XM-L LEDs, the application of Energy Star qualification requires only 3,000 hours of XM-L2 LED LM-80 data, instead of 6,000 hours, according to Cree. It is also UL recognized and features a level 4 rating.

• Size (mm x mm): 5 x 5
• Maximum drive current (A): 3
• Maximum power (W): 10
• Light output: Up to 1,052 lm at 10 W, 85°C
• Typical forward voltage: 2.85
• Viewing angle (degrees): 125
• Binning: 85°C, ANSI
• Thermal resistance (°C/W): 2.5

Table 1: XM-L2 specifications.

Similarly, Cree's XLamp XP-E2 touts a doubling of lumens-per-dollar and up to 20 percent more lumens per watt in the same 3.45 x 3.45 mm footprint, compared to the original XP-E LED. They are also optically compatible with all XP LED designs. This means that lighting designers can effectively increase the lumen output of the XP-E designs for the same cost and power or lower system cost by using fewer LEDs.

Like the XM-L2 LEDs, the XP-E2 LEDs are based on SC3 technology. These LEDs deliver up to 128 lumens/W at 350 mA and 85°C or 143 lumens/W at 350 mA and 25°C in cool white (6,000K). See Table 2 for additional specifications. The XP-E2 LEDs are available in 2,700K to 7,000K color temperatures with minimum CRI options of 70, 80, 85, and 90.

• Size (mm x mm): 3.45 x 3.45
• Maximum drive current (A) white: 1
• Maximum power (W) white: 3
• Light output (white): Up to 283 lm @ 3 W, 85°C
• Typical forward voltage @ 0.35 A (V) 85°C - White: 2.9
• Viewing angle (degrees) white: 110
• Binning: 85°C, ANSI
• Thermal resistance white (°C/W): 9

Table 2: XP-E2 specifications.

For array products, Cree's XLamp CXA integrated LED arrays now delivers more than 10,000 lumens, allowing the LEDs to be used in new applications such as outdoor area lighting, as well as high-bay lighting and high-output track lights. Two of the newest high-light-output LEDs, the CXA2540 and CXA3050 (key specs presented in Table 3) deliver 5,000 to more than 10,000 lumens.

The brightest CXA3050 can be used to replace up to 100 W ceramic metal halide in spot lighting or up to 175 W pulse-start metal halide in high-bay and outdoor area lighting. Cree says the new LED allows lighting manufacturers to expand their product portfolio with higher lumen products.

• Size (mm x mm): 27.35 x 27.35
• Maximum drive current (A): 2.5
• Maximum power (W): 100
• Light output (lm): 5,000 to 10,000
• Typical forward voltage @ 1.4 A (V), 85°C: 37
• Viewing angle (degrees): 115
• Binning: 85°C, ANSI White, 2- and 4-Step EasyWhite

Table 3: CXA3050 specifications.

The CX2540 LED (Figure 2, specifications in Table 4) delivers up to 20 percent higher efficacy at 5,000 lumens and 3,000K than competing LED arrays of similar size, according to Cree. It also has the same mechanical package as the existing CXA2520 and CXA2530 LEDs, which means it can use the same connector and optics solutions.

Figure 2: The CX2540 LED from Cree delivers up to 20 percent higher efficacy at 5,000 lumens and 3,000K than competing LED arrays of similar size (Courtesy of Cree).

• Size (mm x mm): 23.85 x 23.85
• Product options: High CRI
• Maximum drive current (A): 2.1
• Maximum power (W): 86
• Light output (lm): 4,000 to 8,000
• LES (mm): 19
• Typical forward voltage @ 1.1 A (V), 85°C: 37
• Viewing angle (degrees): 115
• Binning: 85°C, ANSI White, 2- and 4-Step EasyWhite

Table 4: CX2540 specifications.

Cree's CXA LED array family runs a wide gamut of specifications and applications. These devices offer from 300 to more 10,000 lumens and are designed for a variety of applications from GU10 lamps and commercial downlights to outdoor area lighting and high-bay lighting. All CXA LEDs have 6,000 hours of LM-80 data published and support TM-21 reported L90 lifetime of over 4 years, even at 105°C, according to Cree. They are also available in 95-CRI options, which push the performance of LED lighting technology.

Not to be outdone, Philips Lumileds is tackling such LED lighting challenges as light output, efficacy, and quality. Designed for outdoor and industrial lighting applications including streetlights, high-bay lights, wall packs and bollards, its LUXEON R line (Figure 3) is said to deliver more light output, higher efficacy and better quality of light while lowering outdoor lighting costs. As an illumination grade LED, the LUXEON R is hot tested and specified.

Figure 3: The Philips LUXEON R is available in five color temperatures of 3,000K, 4,000K, 5,000K, 5,700K, and 6,500K (Courtesy of Philips).

To ensure uniformity, the LUXEON R (see Table 5 for specifications) offers "freedom from binning." The family is footprint compatible with LUXEON Rebel and Rebel ES. The LED delivers a minimum color-rendering index (CRI) of 70.

• Minimum Flux: 160 to 200 lumens
• Minimum forward voltage: 2.5
• CCT: 3,000K, 4,000K, 5,000K, 5,700K, 6,500K
• CRI Min: 70
• Binning: Freedom from binning < 5SDCM
• Testing: Hot tested and specified at Tj=85°C

Table 5: LUXEON R specifications.

Aimed at outdoor and industrial LED lighting, the LUXEON M series offers a high-lumen output of more than 1,100 lumens and typical voltage of 11.2 V, which drives down system cost and improves system performance, according to Philips.

The LUXEON M (Figure 4) is available in 3,000K, 4,000K, and 5,700K correlated color temperatures (CCT), and delivers more than 1,100 lumens with a minimum CRI of 70. Like the LUXEON R family, the LUXEON M is hot tested and specified at 85°C and offers freedom from binning.

Figure 4: Philips' LUXEON M is available in 3,000K, 4,000K, and 5,700K correlated color temperatures (CCT), and delivers more than 1,100 lumens with a minimum CRI of 70 (Courtesy of Philips).

Summary

To help lighting designers lower their costs and speed their time to market, LED manufacturers are addressing the key challenges of light output, quality of light, efficacy and packaging in discrete and array packages. In most cases, the higher light output LEDs can increase the lumen output of lighting designs at the same cost and power or lower the system cost by using fewer LEDs.

For more information on the LEDs discussed in this article, use the links provided to access product information pages on the DigiKey website.