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White LED Charge Pump with 1.1W Audio Amplifier

Industry’s First LED Charge Pump with Integrated Audio Amplifier Saves 50% PCB Area While Providing Highest Efficiency

Product Details

Key Features

Simplified Block Diagram

Technical Docs

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Sampling:
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Key Features

  • High-Efficiency White LED Charge Pump
    • Individual Adaptive Supply for Each LED
    • 4 Low-Dropout LED Current Regulators
    • 24mA to 0.1mA Dimming Range
    • Single-Wire, Serial-Pulse Dimming Interface
    • 1% (typ) Accuracy
    • Low 140µA Quiescent Current
  • Mono Class AB Audio Amplifier
    • 1.1W RMS Mono BTL Output (8Ω, VIN = 5V)
    • Low 0.004% THD+N at 1kHz
    • High 90dB PSRR at 1kHz
    • Fully Differential Inputs
    • -9dB to +18dB Gain Settings in 3dB Steps
    • Integrated Click/Pop Suppression
    • Low Quiescent Current
  • Soft-Start Limits Inrush Current
  • Thermal Shutdown, Open- and Short-Circuit Protection
  • 16-Pin, 3mm x 3mm Thin QFN Package

Applications/Uses

  • Camera Phones
  • Cell Phones and Smartphones
  • PDAs, Digital Cameras, Camcorders

Description

The MAX8678 integrates a charge pump for white light-emitting diodes (LEDs) with an audio loudspeaker amplifier. The high-efficiency, adaptive charge pump drives up to four LEDs with constant current for uniform brightness. The LED current is adjustable from 0.1mA/LED to 24mA/LED in 31 pseudo-logarithmic steps through a single-wire serial-pulse interface. High accuracy and LED-to-LED current matching are maintained throughout the adjustment range. Individual adaptive mode switching for each LED provides high efficiency with a wide range of LED forward voltages.

The mono class AB audio amplifier directly drives an 8Ω loudspeaker with 1.1W RMS continuous power from a 5V supply with less than 1% THD+N. The gain is adjustable from -9dB to +18dB in ten 3dB steps through a single-wire serial-pulse interface. Clicks and pops are suppressed during on/off and all gain adjustments. Differential inputs improve common-mode noise rejection.

The MAX8678 includes soft-start, thermal shutdown, open-circuit and short-circuit protection, and is available in the 16-pin, 3mm x 3mm Thin QFN package (0.8mm max height).

Simplified Block Diagram

MAX8678: Typical Operating Circuit MAX8678: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.