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MAX8857A
Smallest, All-Internal MOSFET, 7-Channel 2 AA DSC PMIC

Highly Efficient 2 AA DSC PMIC


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Description
ABRIDGED DATA SHEET (PDF, 740kB)
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The MAX8857A PMIC provides a complete power-supply solution for digital still cameras (DSCs) and digital video cameras (DVCs). The MAX8857A improves performance, component count, and board space utilization compared to currently available solutions for 2 AA cell and dual-battery designs. On-chip power MOSFETs provide up to 95% efficiency for critical power supplies. The CCD inverter can operate directly from 2 AA/NiMH batteries without the use of any additional external components.
  • Step-up synchronous-rectified DC-DC converter (SU). The MAX8857A is bootstrapped from VSU.
  • MAIN synchronous-rectified step-up DC-DC converter (M) with active discharge for DSP I/O supply voltage.
  • SDZ synchronous-rectified step-down DC-DC converter (Z) for DSP DDR supply voltage.
  • Low-voltage (down to 1V) synchronous-rectified step-down DC-DC converter (SD) for DSP core supply voltage.
  • Step-up DC-DC converter with current regulation and PWM dimming control (LEDBST) for up to 6 series white LEDs (WLED).
  • High-voltage step-up DC-DC converter (CCDBST) for CCD imagers or positive LCD bias supplies.
  • Transformerless inverting DC-DC converter (CCDINV) for CCD imagers or negative LCD bias supplies. This converter can connect directly to 2 AA batteries.
The MAX8857A has an independent/simultaneous power-on sequence of the CCDBST and CCDINV converters. For a preset power-on sequence of CCDBST before CCDINV, contact the factory.

The MAX8857A is available in a 5mm x 5mm, 40-pin thin QFN package and operates over the -40°C to +85°C extended temperature range.

Key Features   Applications/Uses
  • 95% Efficient Synchronous-Rectified DC-DC Converters
  • 90% Efficient Boost-Buck Operation
  • Up to 85% Efficient, High-Voltage DC-DC Converters
  • Inverter Operates Directly from 2 AA Batteries
  • Internal Compensation on All Channels
  • True Shutdown™ on All Step-Up Converters
  • Overload Protection
  • Startup into Short Protection
  • Soft-Start for Controlled Startup Current
  • 100% Duty Cycle on Step-Down Converters
  • Regulated Current Output for Up to 6 White LEDs
  • PWM Dimming of WLED Current
  • Adjustable LED Overvoltage Protection Up to 27V
  • Transformerless Inverting Converter for CCD
  • 2MHz ±2.5% Switching Frequency
  • 1µA Shutdown Supply Current
  • CCD Voltage Sequencing
  • All Internal Power MOSFETs
  • SDOK Power-OK Indicator

 
  • DSCs and DVCs
  • PDAs and Portable Media Players

    Key Specifications:   Multifunction PMICs
    Part Number Primary Topology Monitor/Control Features DC-DC/Power Features LCD/LED/Flash/CCD Features Interface Type VIN (min) (V) VIN (max) (V) Min. VOUT (V) Max. VOUT (V) IOUT (A) Operating Freq. (kHz) Package Smallest Available Package (max w/pins) (mm2)
    MAX8857A  Step-Up Low Batt./POK Output
    Output OVP
    Current Limit
    Fixed Freq./PWM
    Internal Pwr. FETs
    Soft Start
    Sync. Rectifier
    CCD Bias
    TFT Bias
    White LED
    GPIO 0.9 5.5 1 27 1 2000 TQFN/40 26
    See All Multifunction PMICs (79)

    For details, contact your nearest sales office at http://www.maxim-ic.com/company/contact/sales_offices.cfm.

    Diagram
    MAX8857A: Typical Operating Circuit
    Typical Operating Circuit

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    Document Ref.: 19-0987; Rev 0; 2008-10-27
    This page last modified: 2008-11-13


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