The industry has built up a significant case for LED lighting as well as a wealth of products for just about every home and commercial application. The benefits of LEDs have not only been trumpeted but also proven empirically in terms of higher efficiency, longer product life, lower costs, and environmental concerns. LED lighting is here, so when will it arrive?

State of the Art?
Although we see new uses for LEDs emerging on a regular basis, LEDs used for general lighting applications seem to be about as good they can get. Naturally, there’s always room for brightness and efficiency boosts. But in the big picture, excluding commercial and special-effects lighting, have LEDs reached state-of-the-art status? Jordon Papanier, marketing manager for LEDtronics, doesn’t believe that any general design breakthroughs are on the horizon.

“Watts per lumens still needs to improve before we can have a general LED room light bulb that fits in the standard A19 bulb package size,” he says.

On the other hand, Irene Signorino, director of marketing, lighting, and automotive products at Microsemi, is more optimistic.

“The LED lighting market in general is definitively still in its infancy stages. It is true there are some specific LED applications that some industry analysts consider in a mature stage. However, the majority of the market is still a world of many open possibilities,” she says.

“We still have lot of work to do to get to state of the art. Most products are good enough to give the consumer an experience similar to incandescent light in the form of total light and color quality for much less power consumption. This is enough to generate interest in LED lighting. However, there is room for improvement,” concurs Peter DiMaso, strategic marketing, lighting power products, at Texas Instruments.

“Key design breakthroughs will come from cost-effectively adding communication and intelligence to the simple light bulb replacement in the form of intelligent occupancy sensing, color tuning, off-site control, and wireless or wired technologies that will be Internet addressable,” DiMaso says.

So we are not yet at the state of the art on the solid-state lighting (SSL) front, and there is room for improvement and innovation.

“When people think about SSL, they often only consider LEDs, which are just one single component,” says Makarand Chipalkatti, senior director, solid state lighting & emerging market initiatives, at Osram Sylvania.

“There is still much work to be done in the overall system of light delivery including optics, architectural integration, power distribution, controls and communications, and the most critically human factor, understanding that it is not about the light bulb, it’s about the light output,” Chipalkatti notes.

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“General lighting: We are in the early stages of an explosive growth pattern for LEDs,” says Tony Carrella, president of Traxon Technologies and e:cue lighting control. “Consumer products are constantly improving, i.e., lumens per watt, CRI (color rendering index), cost, and build replacement will likely become the most active sector.”

SSL Roadblocks
LED lighting is more efficient, lowering electricity bills. It’s also cheaper in the long run due to a very long product lifespan. SSL is as bright or brighter than traditional incandescent and cold cathode fluorescent (CCF) lighting. And, it’s dimmable.

So what’s the biggest impedance to most consumers making the move to all-LED lighting? Almost everyone agrees that cost is the greatest roadblock to widespread acceptance of SSL. On the front end, LED lighting isn’t cheap.

“The primary blocker for the majority of consumers is still price,” says Heather Goldsmith, global marketing communications manager for Future Lighting Solutions. “Consumers are still reluctant to spend $20 to $30 on an LED bulb when they can buy conventional light bulbs for just a few dollars. Even with soaring energy bills, most consumers are not yet willing to make the initial cost investment for LED lighting.”

In addition to price, other interesting factors are keeping SSL technology at bay for the moment.

“The biggest impedance to the majority of consumers is undoubtedly price,” says Mike Kretzmer, manager of new business development at ERG Lighting. “However, the lack of standardization and suspect quality of early entrants are close behind. Adding fuel to the fire is the fact that LEDs are electronic and lighting has been electrical, which creates a fairly large educational gap between those designing the luminaires and those purchasing them.”

“The main problem is always the fact that any LED light bulb replacement will inevitably be much more expensive than the light bulb that it replaces,” says Peter B. Green, LED group manager at International Rectifier.

“Other impeding factors involve the relative performance of the light source compared to a light bulb and include dimmability, color temperature, or whiteness of the light emitted by LEDs, amount of light produced relative to a light bulb, and whether the light can be effectively and evenly distributed without producing darker areas or odd patterns,” he says.

“The often-mentioned impedance to LED adoption is price. There is still a throw-away mentality with consumers, and they want to be able to purchase a better light source at a price that is equivalent to that of incandescents and CFLs (compact fluorescent lamps),” says Matt Reynolds, applications engineer, SSL division, National Semiconductor.

“Consumers are having a difficult time grasping the payback and long life virtues of SSL and, in general, aren’t aware of what LED lighting offers,” Reynolds adds. “Educating the public and making sure we don’t fall into the CFL trap (an unreliable and poor light source) will be critical, and proof of reliability and payback will need to be displayed.”

On top of costs, Daniel Jacobs, visible LED product engineer for Optek, offers some other viable sources of impedance. “Knowledge is a bit of a roadblock, as consumers are not generally comfortable with SSL technology,” he says. “Misperception is also a problem. Cheap, low-performance products have entered the market and damaged the reputation of LEDs. For example, LED traffic signals, one of the most conspicuous applications of LEDs, have exhibited poor reliability.”

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Summarizing LED maker observations, the greatest hurdles faced by SSL are price, consumer awareness and education, and proof of reliability. Assuming solutions to these issues are underway, when will we see an LED takeover?

Dawn of the LED
LED lighting has been imminent for quite some time now, so exactly what will it take to push SSL into every home? Perhaps a bit of government strong arming similar to the way the Federal Communications Commission forced digital TV upon the public? When will LEDs completely take over as the primary lighting source?

“I feel that without governmental mandates or initiatives, it \\[SSL lighting adoption\\] will happen slowly and could take 10 to 20 years to reach full replacement,” says Brett Shriver, director of sales at Global Lighting Technologies.

“The government is already influencing the market with energy saving legislation, meaning the replacement has already started,” says Hans-Otto Schlothauer, global product marketing manager, LED/lighting, at Sabic Innovative Plastics.

“It is unlikely that the general populace will completely embrace this technology until there is greater standardization or governmental initiative,” says Mike Kretzmer of ERG.

For a complete shift to SSL, Hernan DeGuzman, vice president of marketing at Supertex, cautiously ventures a comparison to digital TV. “Cost is an overwhelming factor. To the consumer, the cost of the digital TV has come down to the same as analog. Likewise, LED bulbs would have to drop to a similar cost or small premium compared to incandescent bulbs,” he says.

International Rectifier’s Peter B. Green points out that, due to the relatively high cost of LED light sources, it is probable that the banning of incandescent light bulbs is necessary to facilitate the general adoption of SSL. “I estimate that in 10 years LEDs will become the primary light source for general applications,” he says.

All respects to cost and government mandates aside, Future Lighting’s Heather Goldsmith takes a more focused and optimistic view. “LEDs will take over as a primary role when lighting solutions for the general illumination market segment is focused on standard rather than custom solutions. The market is ready today. The answer of when is in finding the right LED solution for each customer application,” she says.

Let There Be Light
There’s no shortage of LED-lighting products for consumers and commercial users alike. For example, ERG Lighting’s eDriver family of LED power supplies includes constant voltage and constant current modules (Fig. 1), each of which is 90% efficient. Fully isolated, the modules provide universal inputs (120, 220, 277 V) and power factor correction greater than 90%, as well as 0- to 10-V dimming options.

Combining edge-lit LED light guide technology with mass production capabilities, Global Lighting Technologies offers a slim, light, efficient, and cost-effective troffer downlight (Fig. 2) that delivers bright, uniform light without hot spots or dark areas. Measuring 23.5 by 23.5 in. with a thickness of 0.35 in. and a weight of less than 3 kg, the component delivers a brightness greater than 60 lumens per watt as well as color temperature of 4000K/6000K while consuming 45 W.

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Targeting home-lighting apps, LEDtronics’ flame-tip, surface-mount LED chandelier bulbs come in a flame-tip-shape, UV-protected plastic lens covering that allows the LEDs to shine three dimensionally in multiple directions (Fig. 3). The DEC02SMB11E26 series bulb consumes 3 W while delivering 174 to 202 lumens. Additionally, the bulb provides a 360° radial beam and 135° viewing angle.

The LXMG221W-0700034-D0 power-supply module (Fig. 4) from Microsemi supports five to 16 LEDs and provides a universal input voltage range of 90 to 305 V ac. It also boasts a total harmonic distortion (THD) of less than 20%, constant current single string output of 700 mA, 14- to 48-V dc output for loads of up to 34 W, and peak efficiency of 90%. It’s also dimmable to 10% via 0- to 10-V dimming controls and potentiometers.

Osram’s ultra-white Oslon SSL LED (Fig. 5) is merely 3 by 3 mm, but delivers up to 1 W of output with a luminous efficiency of 100 lm/W. Along with a beam angle of 80°, it specifies a thermal resistance of 7K/W, an operating current of 350 mA, a typical brightness of 110 lm in ultra-white (5700K and 6500K), and a maximum luminous flux of 130 lm.

The AT9917 and AT9932 LED drivers from Supertex target automotive lighting apps, i.e., head, tail, and dome lights, indicators, and panel backlights (Fig. 6). The AT9917 uses a peak-current mode control scheme to drive single switch converters and integrates a transconductance amplifier and a fault output using an external FET. The AT9932 employs a feed-forward current control scheme that achieves low susceptibility to input-voltage transients.

Packing all the necessary hardware and software to develop a digitally controlled LED system, the TMDSDCDCLEDKIT LED dc-dc developer’s kit from Texas Instruments is based on the Piccolo MCU and the controlCARD development platform (Fig. 7). One MCU controls the dc-dc power stage and up to eight LED strings. Notably, the kit is completely open source with gerber files, schematics, and bills of materials (BOMs) all available for free.

Any Challengers?
Technologies come, develop, evolve, and morph, and sometimes they go by the wayside. In any given technology, competitive variations and alternatives usually keep the market interesting. Although LEDs are here to stay until further notice, what other lighting technology could compete with them on any significant level in the general-lighting market? ERG’s Mike Kretzmer sees CFLs as a possibility.

“The lifetime of many CFLs has more than doubled in the past year and initial cost is still far below that of LEDs in many home applications. However, until CFL dimmability vastly improves and a technique for manufacturing them without mercury and other harmful byproducts for disposal emerges, the CFL will be hard-pressed to compete with SSL on cost alone.”

“RF plasma is a higher-power technology, and quantum dot technology is coming in the future,” says Peter DiMaso of Texas Instruments.

“HID (high-intensity discharge) lighting still retains a share of the market due to very high lumens per watt and relatively long life compared with fluorescent lamps, although significantly less than LEDs. Induction lighting also continues to hold a share of the market. These light sources may eventually be replaced by LEDs, but that is not likely to be for several years,” says Peter B. Green of International Rectifier.

“There is some research being done with a high-power type of OLED (organic LED) to make very thin light panels for the office and home, but these light panels get very hot, more so than a halogen bulb. These light panels can be 2 or 4 feet long or cover a ceiling or a room wall,” says Jordon Papanier of LEDtronics.

But the overall consensus in the industry is that LEDs will be the reigning SSL technology in the future. So, nothing out there might give LEDs a run for the money?

“Not at this time and not if we take into consideration the total value proposition,” says Irene Signorino of Microsemi.

“I don’t see any large threats looming at this time,” agrees Matt Reynolds of National Semiconductor.

Getting the final word on the LED question, Tony Carrella of Traxon says, “Not in the real future.”