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MAX8821
White LED Charge Pump with Mono Class D Audio Amp and Dual LDO

Industry's First LED Charge Pump with Integrated Audio Amplifier and 2 LDOs Providing Space Savings and Highest Efficiency


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Status
Active: In Production.

Data Sheet
FULL DATA SHEET (PDF, 912kB)
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Description
The MAX8821 integrates a charge pump for white LEDs, an audio loudspeaker amplifier, and two low-noise LDOs controlled by an I²C control interface. The high-efficiency, adaptive-mode inverting charge pump drives up to six LEDs with constant current for uniform brightness. The LED current is controlled by an I²C interface and adjusts from 0.1mA to 25.6mA per LED into 32 pseudo-logarithmic steps. Independent voltages for each LED maximize efficiency even with large LED forward voltage (VF) mismatch. An internal temperature derating function reduces the current above +40°C to protect the LEDs.

The high-efficiency mono Class D audio amplifier delivers up to 2W into a 4Ω speaker from a 5V input supply. The amplifier features proprietary filterless Active Emissions Limiting (AEL) technology. AEL prevents high-frequency emissions resulting from conventional Class D free-wheeling behavior in the presence of an inductive load. The amplifier offers two modulation schemes: a fixed-frequency mode (FFM) and a spread-spectrum mode (SSM) that reduce EMI-radiated emissions due to the modulation frequency. The amplifier also has robust output protection and high power-supply rejection ratio (PSRR). Click-and-pop suppression is active during power-up/down, enable/disable, and for all mode changes. The amplifier's gain is adjustable through an I²C interface, from -3dB to +24dB in 10 3dB steps. Differential inputs improve common-mode noise rejection.

The LDOs in the MAX8821 are designed for low-noise operation. Each LDO output voltage can be individually programmed by the I²C interface. Both LDO1 and LDO2 have a high 70dB PSRR rating.

The MAX8821 includes soft-start, thermal shutdown, open-circuit, and short-circuit protections, and is available in a compact 28-pin, Thin QFN, 4mm x 4mm package (0.8mm max height).

An evaluation kit is available:  MAX8821EVKIT  

Key Features   Applications/Uses
  • White LED Inverting Charge Pump
    • Independent Adaptive Current Regulators for Each LED
    • 6 Low-Dropout Current Regulators
    • Flexible I²C Dimming Control for Each LED
    • Ramp-Up/Down, Current Control for Each LED
    • Low 70µA (typ) Quiescent Current
    • TA Derating Function Protects LEDs
  • Mono 2W Class D Loudspeaker Amplifier
    • 85% Efficiency (RL = 8Ω, POUT = 600mW)
    • Low 0.05% THD+N at 1kHz
    • High 65dB PSRR at 1kHz
    • Fully Differential Inputs
    • -3dB to +24dB Gain Settings in 3dB Steps
    • Integrated Click-and-Pop Suppression
    • Low Quiescent Current
  • Dual Low-Noise LDO
    • 45µVRMS Output Noise, 70dB PSRR
    • Flexible I²C-Controlled Output Voltages
    • 200mA and 300mA Output Current Drive

 
  • Cell Phones and Smartphones
  • MP3 Players, GPS Devices
  • PDAs, Digital Cameras, Camcorders

    Key Specifications:  White LED Drivers
    Part Number Topology LEDs Config. Dimming Control VDROPOUT
    (mV)
    POUT
    (W)
    ILED
    (mA)
    VIN
    (V)
    VIN
    (V)
    ICC
    (mA)
    VOUT
    (V)
    Oper. Freq.
    (kHz)
    Package/Pins Price
    max num. of typ max min max max max See Notes
    MAX8821  Charge Pump 6 Parallel
    Digital
    I2C Serial
    72 0.6 25 2.7 5.5 0.12 5.5 1000
    TQFN/28
    $2.62 @1k
    See All White LED Drivers (46)

    Diagram
    MAX8821: Typical Operating Circuit
    Typical Operating Circuit

    Evaluation Kits
  • MAX8821EVKIT

    Design Guides
  • Low-Power Notebook ICs (PDF)
  • Audio (PDF)
  • Communications (PDF)
  • Displays (PDF)
  • Automotive (PDF)
  • Medical (PDF)
  • Power Management for Battery-Powered Equipment (PDF)

    Reliability Reports
  • Show FIT data for:
  • Request Reliability Report for:

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
    3. Part number suffixes: T or T&R = tape and reel;+ = RoHS/lead-free;# = RoHS/lead-exempt. More: SeeFull Data Sheet or Part Naming Conventions.
    4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.


    Devices: 1-2 of 2

    MAX8821 Free
    Sample
    Buy Status
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    Temp RoHS/Lead-Free?
    Materials Analysis
    MAX8821ETI+T    
    Active TQFN;28 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0035 (PDF)
    Use pkgcode/variation: T2844+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX8821ETI+  
    Active TQFN;28 pin;17 mm²
    Outline Drawing: 21-0139 (PDF)
    Land Pattern: 90-0035 (PDF)
    Use pkgcode/variation: T2844+1*
    -40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis

    More Information
  • New Product Press Release 2008-03-10 

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    Document Ref.: 19-1014; Rev 0; 2007-11-27
    This page last modified: 2009-08-26


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