New Industry Products

Semtech Expands Multi-String White LED Driver Platform For Medium & Large Displays

September 23, 2007 by Jeff Shepard

Semtech Corp. announced two integrated, multi-string white LED drivers – the SC440 and SC441 – which the company claims give notebook computer and LCD panel manufacturers a compact, high efficiency solution for powering display backlight applications.

The SC440 can power up to six strings of 30mA WLEDs in series and is suitable for notebook computer and other displays that measure up to 15-inches. The SC441 powers up to four strings of 150mA WLEDs in series and is designed for smaller and brighter display applications such as automobile navigation screens or others measuring up to about nine inches. These devices are part of Semtech’s family of display backlighting driver products, and are the first to expand that product platform from small screens to medium and large screens.

The devices feature 91% efficiency at maximum load for improved thermal conditions and longer battery life in portable applications. Screen brightness is kept uniform through an active current matching capability that delivers an industry best 1% (typical) current variation across all strings. Both devices also feature a wide 4.5 to 21V input range to meet voltage levels of portable devices. The devices feature a pulse-width modulation (PWM) dimming control with frequencies up to 50kHz to deliver a linear brightness range of between 0.2 to 100%.

The highly integrated devices both feature a built-in 2.5A power switch and extensive protection mechanisms. The LED open/short circuit detection disables an LED string with an open or short condition without impacting the other strings. The devices also protect the IC from damage caused by over thermal, over-voltage and over-current conditions.

"The SC440 and SC441 provide one of the highest efficiency, integrated power solutions for display makers that want to turn to LEDs for a mercury-free backlight capability," said Ramesh Balasubramaniam, Semtech Marketing Manager, Display Power. "These devices lead the market in efficiency and current matching capability to provide an excellent screen image, and are small enough and flexible enough for all medium and high brightness applications."

The SC440 is housed in a 4mm x 4mm MLPQ-24 (QFN-24) and the SC441 is available in a TSSOP20. Both packages feature an exposed thermal pad to allow for high temperature and high power applications and both are lead-free and WEEE/RoHS compliant.

The SC440 and SC441 are available immediately in production quantities and are priced at $2.13 each in 1,000-piece lots.