Digital Input Class D Speaker Amplifier with Dynamic Headroom Tracking

Efficient High-Power Digital Class D for Battery-Operated Devices Requires No Programming

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The MAX98371 is a high-efficiency, mono Class D audio amplifier featuring dynamic headroom tracking (DHT). DHT automatically optimizes the headroom available to the Class D amplifier as the power supply voltage varies, due to sudden transients and declining battery life to maintain a consistent listening experience. A wide 5.5V to 18V supply range allows the device to reach 19W into an 8Ω load.

The MAX98371’s flexible digital audio interface (DAI) supports I²S, left-justified, and TDM formats. The digital audio interface accepts 32kHz, 44.1kHz, 48kHz, 88.2kHz, and 96kHz sample rates with 16-/24-/32-bit data supported for all data formats. In TDM mode, the device can support up to 16 channels of audio data. A unique clocking structure eliminates the need for an external MCLK signal that is typically needed for PCM communication. This reduces pin count and simplifies board layout.

Active emissions limiting with edge rate control minimizes EMI, and eliminates the need for output filtering found in traditional Class D devices.

An 8-bit PVDD supply voltage ADC enables the Dynamic Headroom Tracking circuit. DHT optimizes audio program peak behavior as the supply voltage varies and provides flexible user-defined parameters.

Thermal foldback protection ensures robust behavior when the thermal limits of the device are exercised. The circuit can be enabled to automatically reduce the output power above a user specified temperature. This allows for uninterrupted music playback even at high ambient temperatures. Traditional thermal protection is also available in addition to robust overcurrent protection.

All MAX98371 control is performed using a standard 2-wire, I²C interface. One of sixteen slave addresses can be selected through two, four-level address pins. The IC is available in a 0.4mm pitch, 30-bump WLP package. It is specified over the extended, -40°C to +85°C temperature range.

For similar function with added brownout protection see MAX98372

MAX98371: Typical Application Circuit MAX98371: Typical Application Circuit Enlarge+

Key Features

  • Wide Supply Range (5.5V to 18V)
  • Dynamic Headroom Tracking Maintains a Consistent Listening Experience
  • Integrated Thermal Foldback Allows Robust Operation in a WLP Package
  • Remote Output Sensing Allows Up to 20dB THD+N Improvement When Ferrites Are Used
  • Class D Edge Rate Control Enables Filterless Operation
  • 110dB A-Weighted Dynamic Range
  • Output Power at 1% THD+N:
    • 15.7W into 8Ω, VPVDD = 17V
    • 13.2W into 4Ω, VPVDD = 12V
  • Output Power at 10% THD+N
    • 19W into 8Ω, VPVDD = 17V
    • 15.8W into 4Ω, VPVDD = 12V
  • Speaker Amplifier Efficiency
    • 91% at 10W into 8Ω, VPVDD = 12V
    • 81% at 15W into 4Ω, VPVDD = 12V
  • Extensive Click-and-Pop Suppression
  • Space Saving, 30-Bump WLP Package (2.1mm x 2.6mm x 0.6mm, 0.4mm Pitch)


  • Notebook Computers
  • Soundbars
  • Tablets

MAXAUDINT001: Evaluation Kit for the MAXQ2000/MAX98357A/MAX98357B/MAX98358 and MAX98371
Request Reliability Report for: MAX98371 
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Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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