The global thrust to reduce power consumption is prompting a change in the way fluorescent light bulbs are controlled. Microcontroller manufacturers are targeting this huge market, providing substantial savings of electricity while also reducing parts count for controller boards.
The change is being driven primarily by regulations in Europe, as well as by U.S. efforts to conserve power and reduce air pollution. "There are so many standards and regulations that it has driven the need for lighting control devices like this," says John Logan, systems engineer at Freescale Semiconductor 8 & 16 Bit Standard Products Division based in Austin, TX.
The firm last month unveiled an 8-bit microcontroller line for this rapidly emerging market. Lighting suppliers and building managers are beginning to replace analog control systems, which have in turn been replacing older magnetic ballast systems. "The market is not growing rapidly, but it's hundreds of millions of units per year," says Stuart Mathieson, technical marketing engineer at Freescale.
Atmel Corp. of Nantes, France, is also joining this market, unveiling a controller developed in conjunction with an unnamed ballast provider earlier this year. Microchip Technology Inc. of Chandler, AZ, is also focusing on this market. Microchip teamed up with International Rectifier, the El Segundo, CA, maker of power components, at the start of the decade to target this market.
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See the Light: Digital controls for
fluorescent lights should provide big savings for users and a big market
for chipmakers.
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Savings for a pair of 36W fluorescents are significant. "Old ballasts lost
16W. We reduce that to 3W," Logan says. Networking and other intelligent
lighting techniques can probably trim another 10 percent, while light output is
increased by about 10 percent, he added. Some of the benefits derive from power
factor correction, and because the frequency is increased. A feedback loop helps
control current more precisely, Logan adds.
While those benefits will be seen by end users, manufacturers will realize other gains.
Instead of producing many different analog controllers, manufactures can make one or two circuit boards, tuning them for different ballasts and bulbs using software.
Additionally, the parts count of these circuit boards can be trimmed by up to half. "An analog dimming controller can have up to 200 parts, a few ICs and a lot of resistor and capacitor. A non-dimming version will have 100 to 150. Our part requires fewer than 80 components," Logan says.
Networked lighting
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Flexibility: Networking using the
digitally addressed lighting interface (DALI) will let facility managers
address lighting banks or individual
lights.
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Today, a single switch will often control many of the lights in a large
office or industrial space. Moving to digital technologies makes it possible to
adjust the levels of specific banks of lights to conserve energy using a new
protocol standard, the digitally addressed lighting interface.
"DALI lets you do things like lighting zones over office cubicles at 50 percent, while areas over walkways are lighted at 30 percent," says Ross Fosler, principal application engineer at Microchip.
Most observers feel that in the U.S., much of the market for microcontroller-based ballasts will be in new construction and remodeled buildings. However, some building owners will be able to upgrade easily. Upgrading won't be difficult in networking in offices, warehouses, or other buildings where wiring is easily accessible.
"If you're not networking, you can just take the old ballast out and put the new one in. Adding DALI requires adding two wires," Mathieson says. Some engineers are looking at the emerging ZigBee wireless standard to eliminate this wiring, he adds.
Vendors also note that additional power reduction techniques can be employed. Adding photoelectrics or other light sensors lets companies take advantage of sunlight to reduce power consumption." Once you get a microcontroller in there, you can measure ambient light and reduce your power consumption, or do things like networking ballasts so they're all turned off at night and turned on at certain times of the day," Mathieson says.
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