Analog Devices MAX98390 Amplifier First Look Video

Welcome to First Look, brought to you by DigiKey and Analog Devices. Modern designs continue to push devices into smaller footprints and slimmer profiles. This leads designers to use compact microspeakers, which compromises loudness(SPL) and decreases bass response due to increased speaker resonant frequencyaudio quality. At the same time, users are relying more on compact, clear audio for interacting with their devices, with smart assistants being a prominent example. To help designers deliver high quality audio while meeting size requirements, Analog Devices has developed Dynamic Speaker Management technology, or DSM. DSM allows designers to safely push microspeakers beyond their stated power ratings while also extending the low frequency range of the speaker beyond the resonant frequency, resulting in audio that is up to 2.5x louder and significantly fuller without any additional programming. In a conventional design, a high pass filter has a cut off at or above the resonant frequency to protect the speaker against overexcursion which can lead to the speaker rupturing, but this also limits bass output. Designers also limit the input amplitude to the speaker to prevent overheating and melting the speaker. However, both techniques leave significant margin that can be recaptured using DSM to improve the audio quality while protecting the speaker against over-excursion and over-temperature events Analog Devices’s MAX98390 DSM Smart Amplifier combines Analog Devices’s current and voltage(IV) sense amps and their patented DSM protection algorithm in a digital, boosted class D audio amplifier. Analog Devices specifically chose to implement the DSM protection algorithm and audio-sweetening features into a fixed-function DSP that requires only a register map that can be completely designed using their easy-to-use DSM Sound Studio GUI. DSM works by using speaker characteristics including the resonant frequency, over-excursion limits, and the thermal properties of the voice coil, paired with the IV feedback from the sense amps to dynamically adjust the output to the speaker. The DSM thermal and over-excursion protections allow the speaker to be operated up to 2.5 times louder and two octaves lower. Previously, obtaining the necessary speaker characteristics necessary to use DSM was a difficult and time-consuming task. However, Analog Devices’s DSM Sound Studio and evaluation system for the MAX98390 make it easy to characterize/customize the protection algorithm for a given speaker, fine tune the amplifier to suit an individual application or use cases, and produce a complete register map The MAX98390 is a highly efficient amplifier designed for use in battery-powered applications. Efficiency can be further enhanced using Analog Devices’s Perceptual Power Reduction, or PPR. PPR filters content that the speaker can’t reproduce or the listener can’t hear, increasing efficiency by up to 25% without impacting the audio fidelity. See you next time on First Look.