MAX158

19-2783; Rev 0; 4/03 High-Efficiency, 26V Step-Up Converter for White LED Main and Subdisplay Backlighting General Description The MAX1582 drives up to six white LEDs in series with a constant current to provide display backlighting for two (main and sub-) displays in cell phones and other hand-held devices. This configuration eliminates the need for ballast resistors and expensive factory calibration. The proprietary dual-output, step-up pulse-width modulation (PWM) converter includes a 30V, low RDSON N-channel MOSFET switch for high efficiency and maximum battery life. The MAX1582 utilizes 1MHz current-mode PWM control to allow small input and output capacitors and a small inductor, while minimizing ripple on the input supply and avoiding interference to sensitive circuitry in the equipment. Integrated overvoltage protection eliminates the need for an external zener diode to protect the IC from open circuit. Flexible dimming control utilizes either an analog control signal or direct digital PWM control without external RC filtering. This also increases dimming accuracy at low brightness levels. The PWM dimming signal can be any frequency from 200Hz to 200kHz. Soft-start eliminates inrush current during startup. The MAX1582 is available in tiny 4 ✕ 4 chip-scale (UCSP™) and 12-pin thin QFN packages. KIT ATION EVALU E L B A AVAIL Features o Accurate Current Regulation for Uniform Illumination o Lights Up Two LED Sections for Main and Subdisplays o Up to 84% Efficiency o Int...