AC drivers gain traction even as AC-LED moniker needs to go (MAGAZINE)

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This article was published in the April 2013 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete April 2013 issue, or view the E-zine version in your browser.

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It may not be a healthy or normal reaction, but I get hung up on misused words. And lately the phrase that has bothered me is “AC LED.” I have no problem with the technology, just the inaccuracy in the use of the name. What we are talking about is techniques for driving an LED rather than a type of LED. I actually think the AC-drive segment of our industry is experiencing a spurt in interest.

Technically inaccurate names come from many sources. I’ve previously spoken out against the way our industry uses “LED package.” It’s accurately the phrase “packaged LED” that describes an LED die that’s mounted on a ceramic base with bond wires/ contacts ready for solder to a circuit board. But the IES put LED package in a glossary, and the rest is history.

I wasn’t specifically covering the LED industry when the term AC LED emerged. I assume an early player such as Lynk Labs or Seoul Semiconductor first used the term. At least early on it was somewhat accurate. Early AC LEDs were essentially multi-emitter packaged LEDs with some of the LEDs oriented in each polarity, called an anti-parallel configuration, such that half of the emitters were powered during each half cycle of the AC-line voltage.

Things have changed dramatically. We last did a feature article on the topic last summer, and a lot has happened even since then. There are varying high-voltage and high-frequency AC-drive approaches that have little in relation to the original AC LEDs other than a drive circuit that’s simpler than the more typical AC/DC driver primarily used in solid-state lighting (SSL).

Now I won’t go into technical detail here, but the point of this editorial is that so-called AC-LED manufacturers no longer introduce products that even closely resemble the term. Moreover, we are about to see AC-driver ICs for LEDs come to market from a number of companies.

Look at our most recent coverage of an LED light engine from Lynk Labs. The company’s intellectual property is purely in how to drive DC LEDs – perhaps in a simpler manner than using an AC/DC converter.

What prompted this column was the new high-voltage LED announced by Seoul targeted at street light applications. The company wants to use its Acrich brand, but the product is purely a DC LED. AC comes only in the form of a small AC-driver IC that the company says can replace the standard AC/DC driver.

Soon I hope we won’t talk about AC LEDs. We may talk about LED AC-driver technology. And multiple companies will offer ICor modular-level products that implement AC drive. Indeed AC and DC drivers are both just different driver topologies with strengths and weaknesses, and the industry will decide which one wins based on product performance and cost.

The AC-LED segment, meanwhile, is fragmenting, as was evident at Strategies in Light (SIL). Companies such as Lynk Labs are becoming mainly module or light engine manufacturers. Vertically integrated LED manufacturers such as Seoul may play across the segment. At SIL, LED maker Epistar sounded ripe to work with AC-driver-IC companies to supply enabling components to SSL or module makers. One SIL presenter, startup Advanced Lighting Technologies, clearly intends to offer driver ICs. We clearly need to address the segment again with a feature soon. We just need a new name for it.