Date: 10/10/2011

Two phase-dimmable AC/DC LED lighting drivers

Texas Instruments Incorporated (TI) has introduced two phase-dimmable AC/DC LED lighting drivers, LM3448 and TPS92070, for use in solid state lighting residential, architectural, commercial and industrial applications, such as retrofit bulbs, LED ballasts, downlights, spot lights and other luminaires.

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

Key features and benefits of the LM3448 as listed by TI include:
Designed for integrated LED lamp form factors that require low component count, high-performance, dimmable LED drivers.
Includes a phase angle dimming decoder compatible with leading-edge TRIAC and trailing-edge electronic dimmers, allowing full-range LED dimming.
Integrated 600-V avalanche-protected, high-voltage and low Rdson MOSFET reduces design complexity while improving LED driver efficiency.
Can be used in both isolated and non-isolated solutions based on the buck, flyback or buck-boost topology, using either active or passive (valley-fill) power factor correction (PFC) circuits.

Key features and benefits of the TPS92070 as per TI include:
Advanced TRIAC dimmer management circuitry accurately decodes dimmer conduction angles and produces a good exponential LED current profile to provide efficient dimming performance and uniform LED light output.
Optimized for valley switching and tight LED current regulation (less than five percent 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.
Can be used in both isolated and non-isolated solutions based on the flyback topology and gives designers the flexibility to optimize their external component selection based on size, cost and regulatory requirements.
Detects the presence of a TRIAC and disables the external PFC function (either valley-fill or active) for improved dimming performance.

Availability, packaging and pricing: The LM3448 is available in volume now in a 16-pin SOIC package and suggested retail price is $1.10 in quantities of 1,000.

The TPS92070 is available now in a 16-pin TSSOP package and is priced at $0.75 in quantities of 1,000.

For more information visit: www.ti.com
TI has recently acquired National Semiconductor.