New LED Drivers Compatible With Many Existing Dimmers, Cirrus Logic Says

Worldwide regulations forcing the transition from incandescent and other inefficient lighting sources to energy-friendly bulbs are a “huge growth opportunity” for semiconductor makers, Biven said. Total light bulb shipments last year were 13 billion-17 billion units, an “amazingly large volume market,” he said. Today, LEDs make up just 2 percent, roughly 230 million, of the total bulbs shipped, but are expected to surge to more than a billion on the back of incandescent replacement business by 2015-2016, Biven said. Compact fluorescent (CFL) bulb sales will continue to grow for the time being because they're a cheaper alternative to LED bulbs, but LED’s longevity, color and environmental benefits will ultimately win out as the price delta narrows, he said.

Cirrus’s primary differentiating pitch for its LED drivers is dimmer compatibility, an issue that doesn’t exist in the incandescent world where bulbs use a simpler design. CFLs and LEDs require additional circuitry to manage the wave form coming out of the dimmer, Biven said. Cirrus has spent four years designing drivers that enable an LED lamp to be compatible with the installed base of incandescent dimmers in the market today, estimated to be 500 million units.

Dimmer compatibility will be a significant issue as more LED bulbs enter the market, Biven said. Compatibility issues can range from flicker or “not a lot of dim range” at the minor end to strobing or not turning off at all at the extreme end, he said. “If you pay more for an LED versus a CFL, you want the bulb to have value,” and Cirrus believes dimmer compatibility is a way to provide value for consumers. Dimmer companies are coming out with products designed to work specifically with dimmable lamps “and sometimes that doesn’t work,” he said.

Getting the message to consumers is tough, Biven said, because the industry isn’t regulated. “Anybody can put a label on the side of a box that says ‘dimmable,'” he said. The Energy Department held a partner meeting last fall to address the compatibility issue, while noting there are many types sources of behavior variation among LED drivers. Some of the final thoughts on a DOE presentation on LED dimming by Michael Poplawski, senior engineer at Pacific Northwest National Laboratory, addressed issues at hand: (1) Consumers want incandescent performance; (2) How much user dissatisfaction is acceptable? (3) Assumptions or generalizations about the impact of the dimmer on the dimming behavior of an LED source is risky; (4) Existing dimmed sockets are hard to address without knowledge of the installed dimmer; (5) Combinational testing is time-consuming and expensive; (6) Avoiding false promises is more important than clearing invisible hurdles; and (7) A forward-looking path, while not ideal, may result in the least confusion, dissatisfaction, and technology perception degradation.

Poor-performing products threaten everyone in the LED supply chain if consumers perceive the technology to be flawed. Until there’s an industry standard for LED dimming, OEMs are trying to put better products on the shelf so consumers gain a “higher level of confidence that when they buy a product from Philips or Osram or Samsung or Cree, they'll come back to buy another one of another form factor or light output because it worked,” Biven said.

Cirrus takes a digital approach to dimming, unlike competitors, Biven said. The driver senses the type of dimmer it’s connected to and then “modifies the way we manage the LED load.” The Cirrus driver senses whether the dimmer is a leading-edge, trailing-edge, or smart dimmer and then manages the output accordingly. Dimmers with motion sensors or timers are tricky because they require power even in the off state, Biven said. “Managing that relationship is tougher than managing other types of dimmers,” he said. The range of dimming solutions makes for a “complex problem to solve,” and Cirrus has filed for more than 100 patents around LED dimming compatibility, he said.

The volume of CFL bulbs sold today, some four billion units annually, shows that consumers will buy “poor performing product,” Biven said. Very few of those work on dimmers, he said. “We're trying to provide products to consumers at a reasonable price that actually does work, and we think that that will advance consumer adoption and lower overall return rates.

Regarding the lighting control market, connected lighting is a tiny bit of the overall LED market for now, Biven said, but it’s an area that’s drawing a lot of consumer buzz. “As you put intelligence inside the lamp, you have the capability to expand on that” by also putting intelligence inside the light bulb for communication between the two, he said. He cited Philips’ ZigBee-based Hue that can be controlled by an iPhone through a hub along with Wi-Fi-based lamps in the works from other manufacturers. The infrastructure around connected lamps is creating “a lot more options,” Biven said, saying “it will become cheaper” to do affordable lighting control in the future.

Cirrus has been monitoring the lighting control space as it relates to total number of lamps shipped, but the average consumer’s interest in connected lighting in the next three to five years -- while it will with the rise of LED shipments -- will represent a “very small percentage of the overall market.” The inherent cost addition will be the limiting factor, he said. “You either put the intelligence in your switch or put the intelligence in the light bulb, but there’s cost associated with that,” he said. Techies will look for the ability to connect, he said, but the average consumer wanting to change a light bulb won’t, he said.