Santa Clara, Calif. National Semiconductor Corp. has debuted a LED driver which the company claims offers the industry’s best phase-based dimming performance for high-brightness LED applications. The LM3450 LED driver integrates active power factor correction (PFC) and phase dimming decoding to provide uniform, flicker-free illumination across a wide, programmable dimming range.
The LM3450, a member of National’s PowerWise energy-efficient product family, is well-suited for use in phase dimmable, 10-watt to 100-watt LED fixtures.
The LM3450 integrates hold circuitry to dynamically adjust the current through the phase dimmer. The dynamic hold circuitry, coupled with a programmable, intelligent dimming decoder, ensures consistent illumination across the full dimming range. The integrated phase dimming decoder interprets the phase angle and remaps it to a 500 Hz PWM output to dim the LEDs.
By using this approach, the LED driver eliminates the problem of the dimmer shutting off or “misfiring” during operation. It also eliminates the need to compensate — by reducing the LED dimming range or continuously burning power to keep the dimmer from misfiring — for inaccurate decoding of the phase angle that results in flicker particularly at very low dimming levels.
Other benefits include an analog adjust input to allow for differentiation such as thermal foldback, interface to sensors or dimmer range adjustability.
The LM3450 can be implemented in either single stage or two stage configurations. The single stage configuration yields the smallest footprint and allows for the highest efficiency when converting from the AC mains voltage, while the two stage configuration provides improved dimming performance and better noise immunity.
Availability: Offered in a 16-pin TSSOP package, the LM3450 is available now.
Pricing:$1.85 in quantities of 1,000.
Resources: National’s lighting products.