According to the study report of IDC - a market research company, the earwear accounted for 21.2% of its total wearable device shipment in Europe in 2018 and it accounted for 52.3% of shipments in the second quarter of 2019, which grew 30%. It can be certain that the audiovisual entertainment consumption habits are changing. From headphones, wired earphones to wireless earphone, the earphones have gradually tended to miniaturized, which makes the products more convenient to use for consumers. Not only be used in conjunction with many electronic devices, but also be equipped with AI techniques, now the earphones are able to be operated by voice to adjust the audio volume, activate Siri without touching the device. Since Apple released the first TWS (true wireless stereo) earphone, the AirPods, in 2016, the demand for Bluetooth earphones has skyrocketed all of a sudden. However, it did not establish a strong demand position in the market until the 3.5 mm headphone jack was removed from iPhone 7.
There are three types of transmission technologies for TWS Bluetooth earphone, as shown in Figure 1. The first is Bluetooth 5.0 (primary and secondary ear transmission technology): By using Bluetooth to connect mobile phone to the primary earphone (normally the right earphone) and then to the secondary earphone through the primary, it takes longer time to connect and higher power consumption relatively due to the additional connection mechanism (for example, Sony WF-1000X/WF-SP700N). The second one is NFMI (near-field magnetic induction), a short-range and high-frequency wireless technology, that communicate between mobile phones by coupling a non-propagating magnetic field with low power consumption (for example, Nuforce BE Free8 and B&O Play Beoplay E8). And the third one is Bluetooth 5.0 with TWS technology that both right or left earphone can independently connect to the mobile phone without the transmission between the primary-secondary earphones, and has the properties as fast connection, energy saving, low power consumption and incredible endurance (for example, Apple AirPods 2 and AVIOT TE-D01b). However, the electronic products such as earphones or earphone s are easily affected by the electrostatic discharge (ESD) generated from human body, or the electrical overstress (EOS) on power terminal. It can cause the abnormal operation of electronic system or product damage resulting in return issue and even impact of company reputation and consumer trust in its brand.
Figure 1: TWS transmission technology
At present, the chips designed for wireless earphone are required to have smaller size with more advanced manufacturing process. There is a clear trend to integrate the processor and Bluetooth chip, which makes the product more vulnerable and sensitive to be easily affected by ESD, and results in more stringent ESD protection requirements. It requires the product to pass the contact discharge testing at 8 kV in the IEC 61000-4-2 standard as the basic requirement. This test method is used to simulate an electrostatic discharge of a human on to an electronic component. The preventive measures can be taken as long as adding appropriate ESD/EOS protection components to the sensitive area and signal lines during circuit design to avoid ESD damage to back-end product or system crash, which results in risk of higher cost.
AMC has advanced ESD protection design and technology, especially for the requirements of earphone protection, to develop a series of ESD protection components with small packages and multiple specifications for customers to choose according to their needs. Nowadays, the major trend in the electronic products is to have light weight and compact size, and it makes strict requirements for component packaging. Small size package can be integrated into system modules, which provides a more flexible ESD/EOS protection. AMC has applied its patented technology to introduce a series of ESD protection components, from 0201/0402 to 01005 ultra-small packages for diverse applications. Each model has ESD immunity, at least, as 8 kV/15 kV for contact/air discharge respectively. Some of them even include the EOS protection, as shown in Table 1. The package size of 01005 has just 0.4 mm x 0.2 mm with thickness 0.1 mm that can greatly meet the demands of TWS electronic products for small package. With the new technology trends of future, AMC will continue to develop ESD protection components to greatly meet customer needs and provide perfection solutions for customized products as well.
Table 1: AMC’s small TVS for earphone applications