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Backlight drivers boost efficiency in portable devices

Maxim Integrated Products introduces the MAX8847/MAX8848, negative charge pumps for up to 6 or 7 white LEDs (WLEDs) in a 3 x 3 mm TQFN package. These backlight drivers employ a negative-charge-pump architecture to eliminate in-line resistance from the battery to WLEDs. As a result, mode switching from 1x to 1.5x is delayed during battery discharge, thereby minimizing dropout.

The proprietary adaptive-mode-switching technology controls each LED individually. The net result of this technology is a 12% increase in LED efficiency and, thus, longer battery life. This extra efficiency makes the MAX8847/MAX8848 well suited for cell phones, smartphones, digital still cameras, and other portable applications.

The MAX8847/MAX8848 can also replace the inductor-boost LED drivers that consume a large piece of PCB real estate in conventional designs. A serial pulse/PWM interface controls each LED, which enables multizone light management and allows up to 32 brightness levels. The 120 microamp quiescent current facilitates "always-on" displays that require minimal power. High LED current accuracy (±2%, max) ensures even brightness and minimizes power dissipation. Built-in temperature derating and overvoltage protection further extend the life of the LEDs.

For more information, contact Maxim Integrated Products, 120 San Gabriel Dr., Sunnyvale, CA 94086. Phone: (408) 737-7600.

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