Smart Amplifier for Micro Speakers Delivers up to 2.5X Loudness and Deeper Sound

Maxim Integrated Products, Inc. introduced the MAX98390 smart amplifier to meet the demand of ever-shrinking products and the increasing adoption of micro speakers. The smart amplifier integrates the company's Dynamic Speaker Management (DSM) algorithm to efficiently deliver louder, clearer, richer sound at what the company claims to be the lowest quiescent power in the market.

The boosted, digital Class-D DSM smart amplifier unleashes a system's full audio potential by safely driving higher power levels (up to 5.1W) into tiny speakers typically rated for much lower power of 1W to 3W.

More applications are moving towards the use of micro speakers to meet the demands of ever smaller devices.

However, as speakers shrink, loudness or sound pressure level (SPL) decreases while the resonant frequency increases, resulting in less bass. Driving the speakers harder for more loudness and increased bass response can easily damage the micro speakers via overheating and over excursion.

The company claims that MAX98390 solves this issue by utilizing integrated current and voltage sense and Maxim's DSM algorithm to drive speakers to their maximum specified limits while protecting against both over excursion and over-temperature events.

DSM's thermal protection enables the safe pushing of speakers beyond their specified power rating, maximizing their loudness. DSM's excursion protection lets designers drive speakers to their specified excursion limits, producing sound that is up to two octaves below the resonant frequency limit.

For proper speaker protection, amplifier algorithms must know the characteristics of the speaker, including resonant frequency within its enclosure as well as excursion limit and voice coil thermal limit.

Traditionally, characterizing the speakers and enclosures required a time-consuming and complex characterization process or relied on direct supplier support to characterize their speakers and enclosures.

This issue is further intensified as most projects begin prototyping with multiple speakers per project, requiring several weeks of supplier support or special equipment and expertise.

Maxim says that MAX98390 significantly reduces the design time. It employs the easy-to-use DSM Sound Studio GUI that allows the quick and easy characterization of many speakers.

The DSM Sound Studio GUI and DSM's thermal protection combined enable maximum loudness across the significantly extended frequency ranges in minutes, with no complex programming required.

To cater to the device miniaturization and shrinking batteries, the MAX98390 offers peak efficiency at 86%, which the company says is even further improved with DSM's Perceptual Power Reduction (PPR) by up to 25% (for maximum efficiency of 89.5%). And it has the lowest quiescent power consumption of about 24mW, making it a suitable choice for low power devices that need longer battery life.

Key Advantages

• According to Maxim, MAX98390 can offer louder and deeper sound quality, delivering up to 2.5x loudness (Sound Pressure Level) and up to 2 octaves deeper bass compared to conventional 5V amplifiers in a small form factor
• Maxim's brand-new DSM Sound Studio software GUI is included, which enables designers to clearly hear the DSM difference in minutes with the Quick Demo feature.
• The software also allows easily characterization and prototyping with designer's own speakers, considerably reducing design time and work

Maxim designed MAX98390 for manufacturability. The company says that MAX98390 allows on-chip DC resistance (Rdc) testing on the production line for quality assurance to ensure a speaker is within impedance tolerance

"Meeting customers' audio expectations given available size and power constraints gets tougher each day," said Michael Van Den Broek, senior applications engineer for PUI Audio. "Having a simplified turnkey solution like the MAX98390 in our toolbox to increase the ability of our micro speakers makes the job easier and our customers much happier—which is the ultimate goal."

"The MAX98390 smart amplifier was designed to boost audio quality in the smallest form-factor to make it nimble enough to go into any device," said Greg Mow, business manager for Mobile Audio Solutions at Maxim Integrated. "From providing the most balanced and loudest sound to offering the market's highest efficiency and ease of design, the MAX98390 enables our customers to deliver a best-in-class, immersive sound experience."

Availability and Pricing

The MAX98390 is available for $1.95 on Maxim's website. Also available from authorized distributors is the MAX98390EVSYS# evaluation kit for $200.