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Stereo Headphone Amplifier with BassMax, Volume Control, and Input Mux

DirectDrive Headphone Amplifier with Integrated 3:1 Input Stereo Multiplexer, I²C Interface, and Industry-Leading Click-and-Pop Suppression

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • DirectDrive Headphone Amplifier Eliminates Bulky DC-Blocking Capacitors
  • 3:1 Input Multiplexer with Digital-Fade Circuitry
  • Software-Enabled Bass Boost
  • 32-Step Integrated Volume Control
  • Beep Input with Programmable Output Level
  • Low Quiescent Current
  • Industry-Leading Click-and-Pop Suppression
  • I²C-Compatible 2-Wire Interface
  • Short-Circuit Protection
  • 1.8V to 3.6V Single-Supply Operation
  • Available in Space-Saving, Thermally Efficient 28-Pin TQFN-EP (5mm x 5mm x 0.8mm)

Applications/Uses

  • Cell Phones
  • Flat-Panel TVs
  • MP3/PMP Players
  • Portable CD/DVD/MD Players

Description

The MAX9729 stereo DirectDrive® headphone amplifier features bass boost, volume control, an input mux, and an I2C/SMBus-compatible serial interface. This makes the MAX9729 ideal for portable audio applications where space is at a premium and performance is essential. The MAX9729 operates from a single 1.8V to 3.6V, and uses Maxim's DirectDrive architecture, eliminating the need for large DC-blocking capacitors. The headphone amplifiers deliver 52mW into a 32Ω load, feature low 0.03% THD+N, and high 90dB PSRR. Maxim's industry-leading click-and-pop suppression circuitry reduces audible transients during power and shutdown cycles.

The BassMax feature boosts the bass response of the amplifier, improving audio reproduction for low-end headphones. The integrated volume control features 32 discrete volume levels along with a ramping function to ensure smooth transitions during shutdown cycles and input selection. The MAX9729's eight programmable maximum gain settings allow for a wide range of input signal levels. A 3:1 multiplexer/mixer allows the selection and summation of multiple stereo input signal sources. The MAX9729 also includes a dedicated BEEP input with independent attenuation control. BassMax, volume control, gain settings, and input selection are controlled using the I2C/SMBus-compatible serial interface. A low-power, 5µA shutdown mode is controlled through an external logic input or the serial interface.

The MAX9729 consumes only 4.8mA of supply current, provides short-circuit and thermal-overload protection, and is specified over the -40°C to +85°C extended temperature range. The MAX9729 is available in a space-saving 28-pin thin QFN package (5mm x 5mm x 0.8mm).

Simplified Block Diagram

MAX9729: Simplified Block Diagram MAX9729: Simplified Block Diagram 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 .