Power Electronics

LED Possibilities Are Dawning on Power Industry

As consumers, we're all getting more and more exposure to LEDs in our everyday lives. We notice the arrays of super-bright LEDs in traffic signals, vehicle lamps, displays and signage. And we hear from the general news media that LED lighting, or solid-state lighting, is poised to revolutionize the lighting industry, replacing both incandescents and fluorescents in countless applications. The often-discussed benefits of LEDs include better efficiency, longer life and greater ruggedness.

Meanwhile, in the semiconductor industry there is the added awareness that LEDs have already made a great impact on power IC development. Just consider how many LED drivers have been introduced in the past five years? The quick answer is too many to count. IC vendors have been steadily cranking out white LED drivers to power the millions of white LEDs used to backlight color LCD displays in portable products, most notably mobile phones.

As iSupply reported at the LEDs2006 conference, the worldwide market for LEDs has grown from just over $2 billion in 2001 to roughly $5 billion in 2005. And that figure is projected to grow to nearly $11 billion in 2011. Those figures include three categories of packaged LEDs: standard devices, high-brightness (HB) LEDs with hundreds of millicandellas of output and ultrahigh-brightness (UHB) LEDs that dissipate 500 mW or more.

According to iSupply, the HB LEDs were 57% of the total LED market in 2005. Nevertheless, the UHB LEDs are likely to be the new driver of market growth over the next five years, as these devices enable many new applications. To date, mobile phones have been the biggest driver of LED sales. As iSupply reported, wireless handsets accounted for more than one-fourth of LED sales in 2005, with most of those LEDs used to backlight LCDs or keypads.

Some of these figures help explain why so many vendors who make power-supply chips have developed extensive lines of LED driver chips and portable power management ICs (PMICs) with LED drivers. Keep in mind that these driver chips and PMICs also target other handhelds such as PDAs, MP3 players and digital still cameras. And besides backlighting, LEDs increasingly provide the camera flash in mobile phones.

Going forward, mobile phones will be a less dominant factor in the development of LED drivers, in part because the handset market is becoming commoditized. But more importantly, the improvements in LED performance and cost are enabling LEDs to be used in many new applications.

At LEDs2006, there were many discussions about these emerging applications. LCD monitors are perhaps the most imminent and exciting market for suppliers of LEDs and LED drivers. LEDs are very much poised to replace CCFLs in computer monitors, but also LCD TVs — even 40 inches or larger. LEDs are even viewed as a light source for rear-projection TVs.

In all these applications, LEDs are likely to succeed, not only because they save energy but because they improve display performance. And in some applications, like compact projectors, they are an enabling technology. Then there are the numerous opportunities for LEDs in automotive lighting.

While all of these applications are significant in their own right, they can also be viewed as a prelude to the widescale adoption of LEDs in general lighting. Already outperforming incandescents, LEDs are on the verge of matching or surpassing the performance of popular metal halide and fluorescent light sources as discussed by Cree's Mark McClear in his recent APEC plenary talk.

It's encouraging to see the power electronics industry paying increasing attention to LED technology, because power electronics expertise will be critical to the success of many LED applications. This month, we devote special coverage to the LED topic in an online section on lighting power management. Go to www.powerelectronics.com to read about methods for powering advanced large-area LED backlights and LED-style MR16 lamps. Also, check out a list of LED-related resources that may be useful to anyone working such power designs. Hopefully, these features will shed some light on the challenges that lie ahead in solid-state lighting and encourage more designers to apply their skills in this growing field.

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