National Semiconductor LM3445: Constant-current controller suits use with triac phase-control wall dimmers

The LM3445 constant-current controller uses a forward or reverse phase-controller triac to enable offline, uniform, flicker-free dimming of high-brightness LEDs. The device has a 100-to-1 range of dimming capability and maintains a 1A constant current to LEDs. The driver interfaces with resistive loads, such as incandescent or halogen light bulbs. An LED bulb does not appear as a resistive load to the wall dimmer, so dimming an LED bulb using a typical triac dimmer yields suboptimal performance. The LM3445 translates the triac-chopped waveform to a dim signal and decodes the signal for a full range of uniform, flicker-free dimming, preventing 120-Hz flicker and the limited dimming range of many other LED drivers. The LM3445 constant-current controller costs $1.75 (1000).

National Semiconductor, www.national.com