Constant current driver providing high-performance dimming performance to lighting


October 13, 2011 -- Texas Instruments (TI) (NASDAQ: TXN) today introduced two highly integrated, phase-dimmable AC/DC LED lighting drivers at the recent Strategies in Light Europe (SIL) conference in Milan, Italy. The new LM3448 and TPS92070 are targeted at residential, building, commercial, and industrial applications such as retrofit bulbs, LED ballasts, downlights, spotlights, and other lighting fixtures.

National's LM3448, an adaptive constant-off time AC/DC constant-current LED regulator, integrates a 600V MOSFET and is optimized for dimmable LED lighting drivers from 2W to 8W. The TPS92070, a flyback AC/DC constant-current LED driver controller, is optimized for dimmable LED lighting drivers from 6W to 20W. Both products provide thermal shutdown, VCC overvoltage lockout, cycle-by-cycle peak current limiting, and open LED protection.

Key Features and Benefits of the LM3448

• Designed for integrated LED lamp form factors requiring low component count, high performance, dimmable LED drivers
• Includes a phase angle dimming decoder compatible with leading-edge TRIAC dimmers and trailing-edge electronic dimmers, supporting a full range of LED dimming functions.
• Integrated 600V avalanche-protected, high-voltage, low-Rdson MOSFETs improve LED driver efficiency while reducing design complexity.
• Available in isolated and non-isolated solutions based on buck, flyback, and buck-boost topologies using active or passive (valley-fill) power factor correction (PFC) circuits

Key Features and Benefits of the TPS92070

• Advanced TRIAC dimmer management circuitry accurately decodes the dimmer's conduction angle to generate a good exponential LED current profile, providing efficient dimming performance and consistent LED lighting output.
• Optimized to provide valley switching and accurate LED current regulation (less than 5% driver-to-driver accuracy) during deep dimming
• Innovative secondary-side feedback eliminates optocouplers and error amplifiers in isolated designs, reducing size and cost while enhancing safety and reliability.
• Available for both isolated and non-isolated solutions based on flyback topology, allowing designers to select external components optimized for size, cost, and regulatory requirements.
• Improved dimming performance by detecting the presence of TRIAC and suppressing external PFC (valley-fill or active) function.

To simplify AC/DC LED driver design, TI offers an online navigation tool that provides complete LED drive solutions tailored to the designer's specifications, including AC input voltage, fixed type, isolation, and dimming requirements. Recommended solutions are provided along with design resources such as datasheets, application notes, and evaluation boards. You can use the AC/DC LED Driver Online Navigation Tool.

The LM3448 and TPS92070 join TI's portfolio of phase-dimmable LED drivers, including National's LM3450, which provides PFC and phase dimming decoding; the LM3445, the industry's first TRIAC dimmable LED driver supporting full-range flicker-free dimming; and the TPS92210, a PFC LED lighting driver with cascoded MOSFETs.

Learn more about TI's LED lighting
• Order samples and evaluation modules
o www.ti.com/lm3448-prkr
o www.ti.com/tps92070-prkr
• TPS92070 demo video: www.ti.com/tps92070-video-prkr
• Download LED reference designs from TI's PowerLab™ design library: www.ti.com/powerlab-prkr
• Ask questions and solve problems with fellow audio engineers in the TI E2E™ Community LED Forum: www.ti.com/ledforum-pr
> Price and availability

The LM3448 is available in a 16-pin SOIC package from TI and its authorized distributors and is currently in production. The LM3448 is priced at $1.10 in 1,000-unit quantities. The TPS92070 is currently available in a 16-pin TSSOP package and is priced at $0.75 in 1,000-unit quantities.