Texas Instruments 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 is an adaptive, constant off time, constant current LED regulator that integrates a 600 V MOSFET and is optimised for 2 W to 8 W dimmable LED lighting drivers. The TPS92070 flyback, constant current LED driver controller is optimised 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.
The LM3448 includes a phase angle dimming decoder compatible with leading-edge TRIAC and trailing-edge electronic dimmers, allowing full-range LED dimming. An integrated 600 V MOSFET which is avalanche protected and has low Rds(on) reduces design complexity while improving LED driver efficiency. The IC can be used in both isolated and non-isolated solutions based on buck, flyback or buck-boost topologies, using either active or passive (valley-fill) power factor correction circuits.
The TPS92070’s 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. It is optimised for valley switching and tight 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.
To simplify AC/DC LED driver design, TI offers an online navigation tool (www.national.com/en/led/bulb/selectortool.html) that delivers a complete LED drive solution tuned to the designer’s specifications, such as AC input voltage, fixture type, isolation and dimming requirements. The recommended solution is provided along with design materials such as datasheets, application notes and evaluation boards.
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