New Class-D amplifiers offer advances for smart and IoT devices

By Aalyia Shaukat, contributing writer

Several chipmakers have recently introduced a lineup of cutting-edge Class-D amplifiers that are a step above those used in the past, with many that are specialized for use in smart technology and IoT devices. Chips such as these potentially pave the way to evolve smart-home-based audio technology and other electronics applications.

Texas Instruments has revealed three cutting-edge new Class-D amplifiers. According to TI, these new amplifiers could lower the barriers to integrating audio into the design of a smart home or other smart devices. These new amplifiers can increase loudness and audio quality while simplifying voice capture with the TAS2770 15-W audio amplifier. This increase in voice-capture ability means easier and more natural operation of voice-controlled devices.

The TAS2770 claims to be the industry’s first audio front-end (AFE) that combines a digital microphone input with a powerful I/V sense amplifier, allowing the device to capture voice and ambient noises for echo cancellation or noise reduction in voice-enabled applications. It also monitors battery voltage and automatically decreases gain when audio signals exceed a set threshold, said TI. This helps prevent clipping and extends playback time without degrading sound quality. These new amplifiers are designed for personal electronics applications at any power level, including smart speakers, sound bars, TVs, notebooks, projectors, and IoT applications.

TI also introduced the TAS5825M audio amplifier that offers 192-kHz audio processing for smart speakers and the AS3251 audio amplifier, touted as the first integrated digital-input solution to support the highest output power and performance at 2 x 175 W in a single package.

The TAS2770 Class-D audio amplifier is now available through the TI store and authorized distributors. Pre-production samples of the TAS5825M are now available through the TI store. The TAS3251EVM evaluation module is available through the TI store and authorized distributors, and production quantities of the TAS3251 amplifier will be available in Q2 2018. Click here for additional information, including pricing.

Another competitor in the market of high-tech audio is Maxim Integrated Products Inc.’s Class-D MAX98357 and MAX98358 amplifiers. Maxim’s new Class-D amplifiers have an efficiency of a 92%, putting it well ahead of the competition, and delivers 3.2 W of Class AB audio performance for high audio quality.

By using a slim and compact wafer design, Maxim has managed to make the amplifiers both smaller and more efficient with a footprint of 1.93 mm² , making them well-suited for use in IoT devices and other low-energy applications. They can be used in a variety of applications.

The Maxim amplifiers claim the highest dynamic range in its product category (103.5 dB), best-in-class total harmonic distortion (THD) noise (0.013%), and excellent click-pop performance (−66 dBV out of shutdown). Another big advantage of the Maxim Class-D amplifiers is that they are designed to be a plug-and-play solution with no need to be formatted. They can auto-configure for 35 different clocking configurations as well as 128 digital audio formats.

Both devices are priced at $0.87 and are available at Maxim’s website and select authorized distributors. The MAX98357EVSYS#WLP and MAX98358EVSYS#WLP (TQFN also available) evaluation kits are available for $59.50.

Diodes Incorporated has also launched a new Class-D amplifier, the PAM8106, designed for use in mobile speakers and devices. This 10-W stereo Class-D audio amplifier features low THD+N, low EMI, and high PSRR while integrating spread-spectrum modulation (SSM) and non-clipping power-limit (NCPL) technology to deliver advanced features for a range of battery- or line-powered devices including LCD TVs, wireless speakers, portable stereos, and game machines.

With its low power consumption, the PAM8106 works well for devices driven by 1.5-V lead-acid batteries, as well as 3.5-V lithium-ion batteries like the ones found in cellphones. It has a high efficiency of up to 92% and can be implemented without the need for a bulky heatsink, allowing for a compact design architecture. The PAM8106 also offers low THD+N to provide speaker protection. The PAM8106 also integrates other protective features into the device and protects against faults caused by short circuits and thermal shutdown.