New Industry Products

TI Introduces First LED Controller with Constant Power Regulation at Lightfair

May 08, 2012 by Jeff Shepard

At Lightfair International, held in Las Vegas, NV, Texas Instruments Inc. (TI) 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, including A19, E26/27 and PAR30/38 bulbs, as well as can light retrofits.

According to TI, 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 new 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.

The LM3447 joins TI’s portfolio of off-line LED lighting controllers that include the National LM3445, which the company says is the industry’s first phase-dimmable LED driver with constant current control, and the TPS92310 primary side regulator for non-dimming applications.

Key features and benefits of the LM3447 LED driver include:

-- Integrated phase dimmer decoding and dimmer detection circuitry allows for easy design and highest efficiency.

-- Operates with leading edge (TRIAC) and trailing edge dimmers.

-- Primary side control supports isolated lighting designs without opto-couplers.

-- Constant power LED load regulation improves efficacy of LED array by compensating for LED junction temperature changes.

-- Fixed frequency discontinuous conduction mode flyback topology with valley switching simplifies EMI filter design.

-- Greater than 0.9 power factor correction meets all regulatory requirements.

-- Thermal fold-back protects LED array from over-temperature while still providing reduced light output.

-- LED open- and short-circuit protection and driver IC thermal shutdown protect lamp electronics from damage during fault conditions.

The LM3447 is available in volume now. Offered in a 14-pin TSSOP package, the suggested retail price is $1.15 in 1,000-unit quantities.

More news and information regarding the latest developments in Smart Grid electronics can be found at Darnell’s SmartGridElectronics.Net.