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LM3445 120Vac Valley Fill Buck Triac Dimmable LED Driver Evaluation Module



  • Constant Current Buck LED Driver
  • 120Vac Nominal Input
  • Triac Dimmable
  • Good Line Regulation
  • Small Form Factor

Texas Instruments  LM3445EVM-695

The LM3445EVM-695 implements a dimming solution using the LM3445 integrated circuit from Texas Instruments. The LM3445 is an adaptive constant off-time AC/DC buck constant current controller with built in phase dimming decoder. Line cycles are analyzed continuously by an internal low power digital controller for shape and symmetry. An analog current reference is then generated and used by the power converter stage to regulate the output current. The analog reference is manipulated using control algorithms developed to optimize dimmer compatibility, power factor and THD. Using constant off-time control the solution achieves low part count, high efficiency and inherently provides variation in the switching frequency. This variation creates an emulated spread spectrum effect easing the converters EMI signature and allowing a smaller input filter.