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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


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Description
FULL DATA SHEET (PDF, 256kB)
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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   Applications/Uses
  • 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

 
  • Cell Phones and Smartphones
  • White LED Backlighting

    Key Specifications:   White LED Drivers
    Part Number Topology Max. No. of LEDs Configuration Dimming Control VDROPOUT (typ) (mV) POUT (W) IMAX per LED (mA) Min. VIN (V) Max. VIN (V) ICC (max) (mA) Max. VOUT (V) Operating Freq. (kHz) Package Smallest Available Package (max w/pins) (mm2) Price**
    MAX8822  Charge Pump 4 Parallel Digital 60 0.4 24 2.7 5.5 1.4 5.5 1000 TQFN/16 10 $1.55 @ 1k
    See All White LED Drivers (46)
    Notes:
    **This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

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    Document Ref.: 19-0847; Rev 0; 2007-12-06
    This page last modified: 2008-01-15


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