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MAX8822：Ultra-Efficient Negative Charge-Pump LED Driver with Dual LDOs in 3mm x 3mm Thin QFN

Independent Adaptive Voltage Supply for Four WLEDs with Two 200mA Low-Noise/High PSRR LDOs for Display Backlighting

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. The MAX8822 features a single-wire, serial-pulse control-logic interface that programs LED current and the output voltages of the LDOs. The LED dimming range is pseudo-logarithmic from 24mA to 0.1mA in 31 steps. LDO output voltages are programmable in 16 different combinations to meet various camera module requirements. The MAX8822 includes soft-start, thermal shutdown, open- and short-circuit protection.

Key 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

MAX8822: Typical Operating Circuit Applications/Uses Cell Phones and Smartphones White LED Backlighting

DataSheet

Parametrics

Design kits & evaluation modules

• MAX8822EVKIT

Quality and Environmental Data

• MAX8822.pdf

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