Principal Chip: Small Chip, Big Market

Hu Yingzhe, a Ph.D. in electronic engineering from Princeton University, returned to China in 2017 to co-found Zhuhai Prinxinchi Technology Co., Ltd.

Recently, at the 10th Songshan Lake China IC Innovation Summit Forum, Hu Yingzhe introduced the SPT50 series chips newly developed by Principal, which are dedicated chips for in-ear detection, pressure detection, touch detection and sliding detection developed specifically for TWS Bluetooth headsets.

Hu Yingzhe said that this is a seemingly inconspicuous chip, but it has become very popular with the booming market of TWS headphones.

As TWS headphones begin to introduce human-computer interaction, functions including smart voice assistants, in-ear detection, and controlling the headphone volume are becoming more and more popular on TWS. Voice interaction is completed through the mobile phone, while other types rely entirely on the TWS hardware system.

The first generation of Apple AirPods used a tapping method, but it was easy to misoperate. When AirPods Pro adopted pressure-sensitive technology, it achieved the continuity of positioning first and then operation without raising the hand, which greatly improved the user experience and gained market recognition. Nowadays, more and more TWS are beginning to choose pressure-sensitive control.

Hu Yingzhe introduced that the current in-ear detection and control of TWS mainly include two methods: pressure sensing and light sensing. Light sensing is more stable and reliable, but it is difficult to assemble, the product yield is low and the cost is high, and it is not suitable for the mid- and low-end markets. Traditional capacitive pressure sensing technology also needs to overcome the following challenges: false triggering due to temperature drift, sweat and other environmental influences, and ear canal adaptation.

Principal achieves high sensitivity through multi-channel detection technology, which can avoid the influence of environmental factors while achieving ear canal adaptation within a distance of 3mm.

TWS pressure sensing technology is also mainly divided into three categories, including capacitive pressure sensing technology used by Apple and Principal, piezoresistive technology of NDT and inductive pressure sensing technology of Azoteq. In comparison, capacitive technology can be machine-mounted, has some advantages in assembly accuracy and compatibility with in-ear touch+, and is easier to achieve mass production. Mass production can be achieved by only machine-mounting shrapnel, and no bracket is required, so the requirements for the assembly plant are low, and the product experience is no different from Apple.

"We have obtained many relevant technical patents and bypassed Apple's related patent layout. Brand customers can choose them with confidence." Hu Yingzhe said.

The core competitiveness of pressure sensing chips is sensitivity. Pressure sensing requires the detection of fF-level changes in capacitance, and for the chip, a sensitivity detection of 0.x fF is required. At the same time, in order to achieve a lower latency experience, a higher sampling rate is required, but at the same time, the power consumption must be low enough. Principal's product performance is: 0.2fF resolution, 100Hz sampling rate and 10uA power consumption.

At present, in addition to TWS headset detection, Prinxinchi's product layout also provides intelligent voice and intelligent audio noise reduction chips, providing a more complete one-stop solution for TWS headset human-computer interaction.