Digital Class D Speaker Amplifiers Deliver the Highest Efficiency in a Compact, Cost-Effective Plug-and-Play Solution


With the MAX98357 and MAX98358 digital-input Class D audio power amplifiers by Maxim Integrated Products, Inc., designers can achieve highest efficiency in a compact, cost-efficient plug-and-play solution. Despite their ultra-small form factors, these Class D efficient amplifiers deliver 3.2W of Class AB audio performance for superior audio quality and are ideal for a wide variety of applications.

Traditionally, electronics designers use analog amplifiers requiring a digital-to-analog converter (DAC) and line driver amplifier on the application processor. This adds overall die cost to the speaker output and affects the form factor of the overall solution size. With the rise of voice-activated consumer devices, designers must also meet today’s increased demand for superior audio quality, while maintaining a simplified, low-power and efficient design.

The MAX98357 pulse-code modulation (PCM) and MAX98358 pulse-density modulation (PDM) plug-and-play speaker amplifiers reduce overall solution size by taking advantage of Maxim’s clever pin-out and by significantly reducing the number of required components compared to typical analog amplifier designs. Since most customers control their volume digitally upstream, these features enable customers to take advantage of Maxim’s cost-effective wafer-level packaging (WLP) without the need for expensive vertical interconnect access (VIAs). For superior audio quality, they feature a digital input for noise immunity, along with highest jitter tolerance (at least 8dB better than competitive solutions). They also offer excellent electromagnetic interference (EMI) performance and allow the use of longer traces to the speakers without added external filtering. In addition, they offer the highest Class D efficiency in the industry.

To simplify design, the plug-and-play functionality only requires users to connect a single power supply and feed the bit clock (BCLK) and left-right clock (LRCLK) of both the MAX98357 and MAX98358, without needing a master clock (MCLK). These amplifiers further simplify designs by auto-configuring for up to 35 different clocking configurations and 128 different digital audio formats. This automatic configuration eliminates complicated I2C programming as there is no longer a need to rewrite base code to configure a design just to add audio functionality. As more applications (such as smart speakers) start requiring multi-directional/channel audio, the need for amplifiers like the MAX98357 and MAX98358 that can be easily daisy-chained to support speaker arrays (up to 8 channels supported by time division multiplex or TDM) will continue to grow.

Key Advantages

  • Superior audio quality: Highest dynamic range in its product category (103.5dB), best-in-class total harmonic distortion (THD) noise (0.013%), and excellent click-pop performance (-66dBV out of shutdown) via extensive click-pop reduction circuitry
  • Cost-effective: Uses WLP with no expensive PCB VIAs required; Only one external component (bypass capacitor) and one supply voltage needed for most applications; Competing solutions require at least two external components as well as internal VIAs and two supply voltages
  • Plug-and-Play simplicity: No programming required.  Requires only a single power supply and auto configures for 35 different clocking configurations and 128 digital audio formats.
  • Compact: Available in a tiny solution size (1.93mm2WLP); Allows three gain levels with easy connection
  • Highest Class D efficiency:Offers highest efficiency of 92% compared to competing solutions