General Description

The MAX8822 drives up to four white light-emitting diodes (LEDs) with regulated constant current for display backlighting in cell phones, digital cameras, PDAs, and other handheld devices. By utilizing a proprietary negative 0.5x inverting charge pump and innovative independent low-dropout (LDO) adaptive current regulators, very high efficiency is achieved over the full 1-cell Li+ battery voltage range, even with large LED VF mismatch. The 1MHz fixed-frequency switching allows for tiny external components. The regulation scheme is optimized to ensure low EMI and low input ripple. Two 200mA, low-noise, high power-supply-rejection-ratio (PSRR) LDOs with programmable output voltages are included on-chip to provide power to camera modules or other devices.

Features

♦ High-Efficiency Charge Pump for Up to Four White LEDs

    Independent Adaptive Voltage Supply for Each LED

    24mA to 0.1mA Dimming Range

    1 (typ) Current Accuracy and 0.3 Current Matching

    Low 65µA (typ) Quiescent Current

♦ Dual 200mA Low-Noise, High PSRR LDOs

    16 Different Output Voltage Combinations Up to 3.3V

    High 60dB PSRR at 10kHz

♦ Flexible Single-Wire Control for Dimming and LDO Output Voltage

♦ Low 0.5µA (typ) Shutdown Mode

♦ Soft-Start Limits Inrush Current

♦ Thermal Shutdown and Open- and Short-Circuit Protection

♦ Tiny 16-Pin, 3mm x 3mm Thin QFN Package

    (0.8mm max Height) with Exposed Paddle

Applications

    White LED Backlighting

    Cell Phones and Smartphones