Charge Pump Drives Up to Six White/RGB LEDs

The MAX8647 negative charge pump reports the industry's highest efficiency in powering LCD backlights. An innovative architecture claims responsibility for eliminating in-line resistance from the battery to the LEDs. The design delays mode switching from 1x to 1.5x during battery discharge, and a proprietary adaptive-mode switching technology controls each of six white or RGB LEDs independently. Reportedly, this achieves a 12% boost in efficiency even with a large forward-voltage mismatch. A companion to the MAX8647, the MAX8648 negative charge pump also employs adaptive-mode switching. A unique function, the MAX8648 groups LED control into three zones with serial-pulse dimming. The MAX8647/8648 are available in 16-pin TQFNs measuring 3 mm x 3 mm. Prices start at $1.95 and $1.70 each/2,500, respectively. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.