The three major pain points of true wireless audio, where is the breakthrough opportunity of TWS chip?

With the rapid development of TWS products, these two small headphones and charging compartments have become an indispensable part of daily audio-visual life. Not long ago, Qualcomm released the 2020 The State of Play survey report, which selected 5,000 users from five countries in the United Kingdom, the United States, Germany, and Japan as the survey objects. The survey results show that 42% of users worldwide have TWS products this year, compared to 23% in the 2019 report, with strong growth in every region.

With the rapid development of TWS products, these two small headphones and charging compartments have become an indispensable part of daily audio-visual life. Not long ago, Qualcomm released the 2020 The State of Play survey report, which selected 5,000 users from five countries in the United Kingdom, the United States, Germany, and Japan as the survey objects. The survey results show that 42% of users worldwide have TWS products this year, compared to 23% in the 2019 report, with strong growth in every region.

The survey results further show that sound quality, battery life and active noise reduction have become the three most critical factors in product parameter characteristics. As for battery life, other countries expect usage in the 9 to 11 hours range, while Chinese users have the highest battery life expectations for TWS products at 18 hours. At the same time, the further popularity of TWS is also supported by cloud-based voice assistants. However, to achieve these performance requirements, we have to mention the chips in TWS products.

In view of the small size of TWS, such chips often need to be highly integrated, with high performance, low power consumption and low cost as the main premise. In the domestic TWS market, which is still in the stage of extensive growth, players at all levels appear frequently.

More practical active noise cancellation

Sophie Mao, Marketing Manager of Consumer Products at ADI China, expressed her views on the future of the domestic TWS market. She believes that TWS products will be differentiated in the future, emphasizing performance and cost performance respectively. Among them, active noise cancellation (ANC) will become the standard configuration of TWS headphones. ADI believes that more than half of TWS headphones will have ANC function in 2023.

The three major pain points of true wireless audio, where is the breakthrough opportunity of TWS chip?

ADAU1787 Evaluation Kit/ADI

As a pioneer of digital and analog chips, ADI mainly promotes ANC solutions ADAU1787 and ADAU1777 on TWS products. These two solutions achieve higher sound quality with lower power consumption cost. Take ADAU1787 as an example, the chip provides 4-channel ADC input interface and 4-channel digital microphone parallel input, so a single chip can be used for hybrid noise reduction headphones. ADAU1787’s unique dual DSP core design uses FastDSP core for active noise reduction filter processing and SigmaDSP core for EQ post-processing, so as to compensate for the low-frequency lossy part of the music after noise reduction. Under the 2.3 * 2.8 mm BGA package, the power consumption of 1.8V is only 6-7mW, which can be used for TWS applications with strict requirements on size and power consumption. In addition, some functional modules can be reduced by customization to achieve a smaller current and further reduce power consumption.

For the safety of users, ADI has also added a PID proportional-integral-derivative control logic to the chip, which predicts the routing of subsequent signals according to the received signal, for example, to avoid the loud noise when the door is closed, so as to better Protect the user’s hearing. This also benefits from different modes and microphone configurations. ADI’s chip can provide multi-level adjustments such as strong noise reduction, weak noise reduction, noise reduction off and transparent mode.

More efficient charging rate

Battery life is also one of the three most important factors for consumers. In TWS products, each earphone often has an independent small battery, plus a slightly larger battery in the charging compartment. Therefore, the charging rate of the charging compartment is actually also crucial to the battery life experience. For earbuds with limited volume, each end is often equipped with a linear charger, which requires a voltage greater than the battery itself when charging. However, the batteries in the charging compartment and earbuds are often single-cell lithium-ion batteries, and the voltage is usually between 2.5V and 4.2V based on the state of charge. Therefore, the battery voltage of the charging compartment needs to be increased or decreased depending on the situation in order to provide a suitable voltage for charging the earbuds.

The three major pain points of true wireless audio, where is the breakthrough opportunity of TWS chip?

TPS63810 Schematic / TI

At this time, it is time for the voltage converter to show its talents. However, the boost converter will dissipate more energy on the linear charger, which is not only bad for charging efficiency, but also increases the heat dissipation burden of the charging compartment, especially when the earbuds are completely dead. TI’s TPS63810 buck-boost converter can effectively solve these problems. Compared with the 70% to 72% charging efficiency of the boost converter, the buck-boost converter can achieve 92% to 93% without overheating. The output voltage of the TPS63810 can be adjusted via I2C to dynamically set the voltage best suited for the earbud linear charger. TI has also specially developed a three-in-one I2C control switch charging chip for the TWS earphone charging compartment, BQ25618/BQ25619, which optimizes the operating efficiency of the switch mode with a low-impedance power path, further shortening the battery charging time.

More advanced Bluetooth protocol

With the launch of Bluetooth 5.2, TWS has also ushered in new technological innovations, not only adding new LE audio, but also achieving lower latency with the help of synchronization channels. To this end, Telink Microelectronics has launched the multi-protocol chip TLSR9518 for the next generation of TWS products. The TLSR9 series is also Telink Microelectronics’ full RISC-V architecture chip.

TLSR9 series development board / Telink Microelectronics

The chip is based on the RISC-V architecture and is designed to maximize the performance of the device. The MCU is a 32-bit 5-stage pipeline structure, and the CoreMark reaches 3.58MHz. Telink Microelectronics has also added an always-on AI engine to the chip, supporting functions such as multi-sensor fusion and voice wake-up. The most important thing is naturally the support of the Bluetooth 5.2 protocol. In addition to the LE audio and synchronization channels, the chip also supports indoor positioning (AoA/AoD) and Bluetooth Mesh. Of course, this multi-protocol chip is also suitable for wearable and other IoT devices, so it also supports ZigBee 3.0, OpenThread and Telink’s own 2.4GHz proprietary protocol.

lower latency

With the growth of the TWS market, the influence of such products has also begun to spread to the game market. According to Qualcomm’s survey results, in the daily use of TWS users, 17% are used for console games, 16% are used for computer games, and 16% are used for mobile games. In the eyes of heavy game users, the most difficult problem for TWS to solve is delay. In the scene of daily video and audio playback, the difference of hundreds of milliseconds is difficult to be noticed. But in a game that requires concentration of the eyes and ears, the delay will be infinitely amplified.

Qualcomm has launched the corresponding codec method aptX low latency, which can achieve a minimum delay of 40 milliseconds while ensuring 16-bit sound quality. However, as an emerging form of Bluetooth headset, TWS still needs to be popularized for various encoding and decoding methods. However, people still pursue seamless play under unconstrained TWS.

The three major pain points of true wireless audio, where is the breakthrough opportunity of TWS chip?

PAU1625 / Yuanrui Technology

Audiowise, a subsidiary of PixArt (Original Technology), specially developed the PAU1600 series of chips for this pain point. These series are all Bluetooth 5.0 wireless audio SoCs, but Yuanrui realizes the function of binaural direct connection through the unique GreenRadio patented technology. Although only SBC/mSBC and AAC codecs are supported, this series of chips can achieve extremely low latency for TWS products. The PAU1625 chip can achieve a delay of 60 milliseconds in game mode, which is basically imperceptible. From the certification library of the Bluetooth Alliance, it can be found that Yuanrui Technology will launch a new PAU1800 series in the future. This series adopts the Bluetooth 5.1 series and the new generation of green wave technology (GreenRadio 2.0), which may push the delay of TWS products to a lower value.

summary

In fact, people’s pursuit of TWS products is not entirely based on performance parameters. User experience and comfort are also the dominant factors that lead to customer purchases. Although security and privacy are also important aspects of product design, few users will give up purchasing TWS products because of these.

Although the function of voice assistant is for convenience, it must save hardware resources when designing, and it is difficult for TWS to achieve built-in integration. The sound quality is still determined by algorithms and chip performance, such as surround sound effects such as Dolby and DTS. It is also difficult to achieve breakthroughs in the short term in the pursuit of compact TWS. In any case, in the long run, sound quality, battery life and noise reduction will still be the three major driving forces for the explosive growth of TWS, and the TWS chip is still the primary target.

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