Texas Instruments Incorporated(TI)has introduced a new LED controller with constant power regulation.The LM3447 AC/DC LED driver includes a dimmer detect,phase decoder and adjustable hold current circuits to provide smooth and flicker free dimming operation in off-line,isolated LED lighting applications.They are also suitable for A19,E26/27 and PAR30/38 bulbs,as well as can light retrofits.
Traditional drivers use constant current control to accurately regulate LED forward current.This approach produces consistent light output or intensity from LEDs in the same bin.However,once current is applied to the LED,its solder point temperature rises,leading to a decrease in forward voltage and a drop in efficacy.Conversely,by using the LM3447 with constant power regulation,the LED forward voltage droop over temperature is offset by an increase in LED current to maintain constant LED power.The result is up to 10 percent improvement in efficacy across the expected operating temperature range of the fixture.
Features of LM3447 LED driver:1.Integrated phase dimmer decoding and dimmer detection circuitry2.Operates with leading edge(TRIAC)and trailing edge dimmers3.Primary side control supports isolated lighting designs without optocouplers4.Constant power LED load regulation5.Fixed frequency discontinuous conduction mode flyback topology with valley switching6.>0.9 power factor correction7.Thermal fold-back feature8.LED open-and short-circuit protection and driver IC thermal shutdown
The LM3447 is offered in a 14-pin TSSOP package and is available in volume.The retail price is$1.15 in 1,000 unit quantities.
