National Semiconductor Touts LED Energy-Management System
By Byron Pope WardsAuto.com, Oct 20, 2008 5:09 PM

DETROIT – National Semiconductor Corp. introduces an energy-management system it says can help usher in the widespread implementation of light-emitting diode headlights.

National's PowerWise LED drivers are able to closely control the amount of current leading to a LED, which can lengthen the life of lighting components, says Kevin Daugherty, a field application engineer for the Santa Clara, CA-based supplier.

“The intensity of LEDs degrades over time,” Daugherty tells Ward's at the 2008 Convergence Transportation Electronics Conference here.

“What this (controller) does is drive a wide variety of LEDs with a fair amount of accurate current,” he says. “Our job is to drive them in a relative way, so they don't get overstressed with too much current. You can damage them pretty easily.”

Additionally, National's driver can shut down all power to the LED assembly when it's not in use, which greatly reduces the amount of power drained from the battery.

“We (have) a special feature where you can disable all of the current, so it essentially has no current count,” Daugherty says. “(Competitors) would have to add extra circuitry to disable things and disconnect (the light from the battery). This simplifies things.”

The technology also is able to control all headlight functions, including dimming, low and high beam, fog lights and turn signals.

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“What we do is take the standard battery voltage and boost it up to drive several LEDs in strings, so you don't need a separate controller for each one of them,” Daugherty says.

“You have to have a boost-type controller and a current controller, because you're really controlling the current in LEDs. That's what dictates the power and the brightness.”

National currently provides its energy driver to a high-end European auto maker, he says, declining to reveal the company's identity.

While systems, such as National's driver, can help auto makers adopt LED technology, there still are obstacles to overcome that so far have largely relegated the technology to luxury vehicles.

“LEDs really found their way in stoplights and taillights, but those are simple in comparison to the headlight with high, low and fog (lights), so there's a lot of cost associated with that,” Daugherty says.

“But the cost curve is coming down. It's just a matter of time before you find LED headlights in high volume.”

bpope@wardsauto.com