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Smart Class-D/G Amplifier Features Inaudible Noise Floor, Low Quiescent Power

June 28, 2021

Higher fidelity, extended battery life, and support for features like gesture-based interfaces are some of the advances Maxim built into its MAX98396 speaker amp.

Lee Goldberg

Related To: Electronic Design

The MAX98396 Class-D/G speaker amplifier developed by Maxim Integrated Products brings higher fidelity, longer battery life, and support for advanced features, such as gesture-based interfaces, to always-on remote and portable speakers. The 20-V digital input audio power amplifier consumes only 12.7 mW of quiescent power (at 12-V power V_DD, or PVDD), which the company says represents a nearly 80% reduction over comparable amplifiers on the market. This meets or exceeds the industry’s power compliance regulations for the always-on feature in portable Bluetoothand smart speakers. The MAX98396’s low 15.5-µV rms noise floor is 50% lower than the closest competitor, allowing for speaker placement in near-silent locations.

The MAX38396 amplifier offers low quiescent current for smart-speaker applications.

In addition, the MAX98396 is “ultrasound ready,” built to support a digital data channel used as a control interface for smart speakers to implement advanced features like touchless gesture-based sensing, presence detection, and proximity sensing. This ultrasonic channel, operating at roughly 45 kHz, is made possible by the amplifier's upgraded sampling frequency of up to 192 kHz, and a 50-kHz ultrasound signal bypass path that prevents ultrasound signal attenuation by the audio-processing signal path.

The MAX98396 is available at Maxim’s website for $1.12 (1000-up, FOB USA), as well as from authorized distributors. The MAX98396EVSYS evaluation system is priced at $184. You can learn more about the MAX98396 from the video below or at the product’s home page: http://bit.ly/MAX98396Product.

About the Author

Lee Goldberg | Contributing Editor

Lee Goldberg is a self-identified “Recovering Engineer,” Maker/Hacker, Green-Tech Maven, Aviator, Gadfly, and Geek Dad. He spent the first 18 years of his career helping design microprocessors, embedded systems, renewable energy applications, and the occasional interplanetary spacecraft. After trading his ‘scope and soldering iron for a keyboard and a second career as a tech journalist, he’s spent the next two decades at several print and online engineering publications.

Lee’s current focus is power electronics, especially the technologies involved with energy efficiency, energy management, and renewable energy. This dovetails with his coverage of sustainable technologies and various environmental and social issues within the engineering community that he began in 1996. Lee also covers 3D printers, open-source hardware, and other Maker/Hacker technologies.

Lee holds a BSEE in Electrical Engineering from Thomas Edison College, and participated in a colloquium on technology, society, and the environment at Goddard College’s Institute for Social Ecology. His book, “Green Electronics/Green Bottom Line - A Commonsense Guide To Environmentally Responsible Engineering and Management,” was published by Newnes Press.

Lee, his wife Catherine, and his daughter Anwyn currently reside in the outskirts of Princeton N.J., where they masquerade as a typical suburban family.

Lee also writes the regular PowerBites series.