LM3445

LM3445 Triac Dimmable Offline LED Driver February 10, 2009 LM3445 www.DataSheet4U.com Triac Dimmable Offline LED Driver General Description The LM3445 is an adaptive constant off-time AC/DC buck (step-down) constant current controller designed to be compatible with triac dimmers. The LM3445 provides a constant current for illuminating high power LEDs and includes a triac dim decoder. The dim decoder allows wide range LED dimming using standard triac dimmers. The high frequency capable architecture allows the use of small external passive components. The LM3445 includes a bleeder circuit to ensure proper triac operation by allowing current flow while the line voltage is low to enable proper firing of the triac. A passive PFC circuit ensures good power factor by drawing current directly from the line for most of the cycle, and provides a constant positive voltage to the buck regulator. Additional features include thermal shutdown, current limit and V CC under-voltage lockout. Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Triac dim decoder circuit for LED dimming Application voltage range 80VAC – 270VAC Capable of controlling LED currents greater than 1A Adjustable switching frequency Low quiescent current Adaptive programmable off-time allows for constant ripple current Thermal shutdown No 120Hz flicker Low profile 10 pin MSOP Package Patent pending drive architecture Applications ■ ■ ■ ■ Retro Fit Triac Dimming Solid State Lighting Industrial and Commercial Lighting Residential Lighting ...