this week rolled out a light-emitting diode (LED) controller that eliminates
flicker during full-range dimming of LED lights.
the LM3445, the new
product enables users to replace halogen or incandescent lights with LEDs in
homes, restaurants and architectural applications. The device could be
significant because it solves a flicker problem that commonly occurs when users
with TRIAC (triode for alternating current) dimmers install LED lighting.
introduction of LEDs, a lot of customers want to replace halogen or incandescent
bulbs with LED bulbs," says Kristen Elserougi, technical marketing engineer
for National Semiconductor. "But there's a problem with that. Today's LED
driver solutions often don't provide full dimming range, or they don't allow
for uniform dimming of LEDs without flicker."
Semiconductor engineers say the core of the problem lies in the fact that
today's TRIAC dimmers are designed to interface with resistive loads, such as
incandescent or halogen light bulbs. The company's engineers say they've solved
the problem by enabling their new LED driver to emulate that resistive load.
"The 3445 will
translate the chopped waveform from the TRIAC dimmer to a signal for the LEDs,"
Elserougi says. By doing so, it eliminates the 120-Hz flicker that would
otherwise be present and enables a full 100:1 dimming range.
Semiconductor engineers say a system including the LM3445 and as many as
60 LEDs in serial or parallel strings can be created using the company's
Webench LED Designer suite of tools. "With Webench, a mechanical engineer can
do this as easily as an electrical engineer," Elserougi says. "Everything is
spelled out for them."