Multi-string white LED drivers feature 91% efficiency

Camarillo, Calif. — Semtech Corp. has released two integrated, multi-string white LED drivers, the SC440 and SC441, that give notebook computer and LCD panel manufacturers a high efficiency solution for powering display backlight applications.

The SC440 can power up to six strings of 30 mA 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 150 mA 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.

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.

The SC440 and SC441 feature a wide 4.5-V to 21-V input range to meet voltage levels of portable devices. Both devices also offer a pulse-width modulation (PWM) dimming control with frequencies up to 50 kHz to deliver a linear brightness range of 0.2% to 100%.

The highly integrated devices both feature a built-in 2.5-A 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 is housed in a 4 x 4-mm 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. The devices are lead free and WEEE/RoHS compliant.

Pricing: Both the SC440 (order code: SC440MLTRT) and SC441 (order code: SC441TETRT) devices are priced at $2.13 each in quantities of 1,000.
Availability: Available immediately in production quantities.
Product information: SC440 and SC441

Semtech Corp. , 1-805-498-2111,

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