Want your speakers to sound loud enough?The key technology behind it is very important

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Want your speakers to sound loud enough?The key technology behind it is very important

Posted Date: 2024-01-22

In today's consumer electronics market, micro speakers have been widely used in a variety of devices, including gaming devices, smart home IoT devices, and wearable devices. Although those who turn up the sound of personal electronic products very loudly in public places are often annoying, when buying, you will certainly prefer those that have a wider loudness range while ensuring fidelity. How to improve micro speakers Loudness and bass response have become major design considerations for many audio designers.

Although these micro-speakers are small in size, their basic components - diaphragm, voice coil and magnet - are no different from traditional speakers. However, due to its smaller components and simpler structure, its overall appearance is also more compact and thinner. However, the small size of microspeakers also presents some challenges. Its volume (sound pressure level) and bass response are usually limited because the smaller the speaker, the higher the resonant frequency, resulting in bass attenuation and weaker sound performance. However, by continuously monitoring and protecting the speakers from fault conditions, the volume and bass response of the speakers can be significantly improved.

In micro-speaker applications, the reliability challenges faced by devices have changed significantly compared to previous large-size speakers: the coil temperature of micro-speakers may be as high as 100 degrees Celsius in a closed mobile phone, for example, and the vibration amplitude of the diaphragm It is also possible to reach the mechanical limit (exceeding the limit will cause the coil to collide with the magnetic circuit or the diaphragm to collide with the top plate protective cover).

Standard amplifiers are unable to monitor and protect speakers from these two conditions, so speaker power ratings are often conservatively set. The intelligent driver chip can calculate the impedance curve of the speaker by real-time monitoring of the voltage and current of the speaker drive signal, and further derive the resonant frequency, amplitude, and temperature rise of the speaker (or module), and these parameters will vary depending on the signal. Dynamic changes occur due to differences and changes in the environment.

This is where ADI’s patented Dynamic Speaker Management (DSM™) technology can play a key role. DSM technology provides a safe way to drive microspeakers beyond their specified maximum power rating. The DSM algorithm can increase volume (sound pressure level) by up to 2.5 times and extend bass response up to two octaves below the resonant frequency, while achieving excellent power efficiency.

Offering overshoot and overtemperature protection, the MAX98390 drives speakers to their maximum limits

Today's consumer devices require speakers to fit into smaller spaces, resulting in an increasing number of applications using tiny speakers. The smaller the speaker, the lower the volume or sound pressure level (SPL) and the higher the resonant frequency, resulting in attenuation of the bass. By increasing the micro-speaker driver to increase the volume and low-frequency response, it is easy to cause overheating and excessive diaphragm swing, damaging the micro-speaker.

The MAX98390 is a boosted digital DG class DSM smart amplifier in a 6.3mm2 package that safely drives micro speakers that are typically rated at lower power (up to about 3W) to higher powers (up to 5.1W), fully releasing system's full audio potential. At the same time, it can also be used with 5W speakers to further enhance the volume and bass effect.

By using integrated IV (current and voltage) detection technology and ADI's proprietary DSM algorithm, the MAX98390 can drive the speaker to its maximum limit and provide overshoot and overtemperature protection to easily overcome the above design challenges. The thermal protection function of DSM devices enables designers to drive speakers safely and stably, break through the rated power limit, and obtain maximum volume. DSM diaphragm protection enables designers to drive speakers to the specified limits of their diaphragms, breaking through the lower limit of resonant frequency and improving low-frequency response (two octaves).

In summary, MAX98390 can bring several advantages to micro speakers: larger volume and bass sound effects. Compared with traditional 5V amplifiers, the volume is increased by up to 2.5 times (sound pressure level), and the low-frequency sound range is expanded by 2 octaves. Small size package; easy to use, with ADI's new DSM Sound Studio software GUI, the system functions can be quickly demonstrated, allowing designers to clearly hear the DSM application effect in a few minutes, and easily characterize their own speakers Analysis and prototyping, significantly reducing design time and workload; Industry-leading power consumption: Providing the lowest static power consumption in the current market, the peak efficiency of the boost Class D amplifier is as high as 86%, relying on ADI's perceived power reduction ( PPR) patented algorithm can further increase power by an additional 25% without losing audio fidelity. The minimum static power consumption is only 24mW, effectively extending battery life without reducing fidelity.

Quickly design smart amplifier solutions with the DSM Sound Studio GUI

To effectively protect a loudspeaker, amplifier algorithms must be based on a thorough understanding of the loudspeaker's characteristics, such as resonant frequency, diaphragm swing limits, and voice coil thermal protection. Traditionally, designers have had to go through a time-consuming and complex characterization process or rely on supplier support to characterize their speakers and their enclosures. Design challenges are further compounded by the fact that most projects use different loudspeakers during the prototyping phase, requiring supplier support for up to weeks or requiring special equipment and expertise.

But with ADI's DSM Sound Studio GUI, this process has become easier and faster than ever, and it takes less than 3 minutes to describe and customize the speaker's protection algorithm. DSM Sound Studio is the GUI tool in the MAX98390 for speaker parameter extraction, tuning, and custom DSM settings. There is also an optional GUI, the MAX98390C/D evaluation software, which can be used to change the amplifier configuration, such as boost voltage, current limit, etc.

DSM Sound Studio enables fast demos, ultra-fast speaker characterization, tuning, and easy evaluation of different speakers and different tunes. DSM Sound Studio V2 provides users with a better user experience by providing more detailed relevant help, optimized parameter extraction and richer stereo functions to help complete simple self-guided design.

The MAX98390 uses the easy-to-use "DSM Sound Studio GUI" to help customers quickly and easily perform characteristic analysis on a variety of speakers, significantly reducing design time. Combined with DSM's thermal protection feature, you can achieve maximum volume over an ultra-wide frequency range within minutes without complex programming.

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