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USB TypeC Protection Design for Charge Input & Output Port of Wearable Devices

2018/02/20

The main stream of personal electronic devices have changed from early Information Technology(IT) devices such as Personal Computer(PC) and Notebook(NB) till SmartPhone and Tablet such kind of consumer devices for convenient communication and getting information. You can see that electronic devices infiltrate human life increasingly. As the concept of wearable device was put forward, the "smartwatch", "smartband", and "wearable camera" were commercialized and introduced to the market boomingly. These wearable devices have solved the issue of distance between consumers and electronic products. In the other side, because numerous important electronic brand companies developed relative wearable devices competitively. But it also attract the masses for much more expectation to the development and application of wearable devices.   


 The wearable devices in the present market are still mainly for supplying information and notification to consumers. Or getting the body faculty parameters of consumers such as recording as exercising or fixing position. According to the development of IoT such as Cloud and Big Data, the wearable device would take the responsibility to gather important front side data. The requirement of wearable device function would increase in the future. Right now the Head-Mounted Display is mainly for gaming application but it could also be for consumer wearable application because of cost down in the future. There are unlimited possibilities for wearable device application in the coming. Numerous IC design houses were attracted to build any kind of wearable application platform. Wish to lead wearable products to next large growth of electronic industry in accordance to the imagination and creativity of the developers.           


Because the functions of wearable devices would much more and complicated, the choice for interface of data transmission and charge is very important. The USB TypeC interface would be the best choice for its tiny space, reversible plug orientation, integration of high speed data and high resolution video transmission, especially supply the highest 100W power for USB power delivery. Since the USB TypeC was adopted by Apple Mac Book, USB TypeC have been already to be the main interface including in Main Board, NoteBook and smartphone. Thanks to the support and promotion of USB Implementers Forum and Intel that the USB TypeC could be so popular and start a new revaluation for the interface. USB TypeC solve the complicated requirement of high speed signal and power delivery through just one cable. That's why USB TypeC was be expected to rule the union interface between wearable devices and other electronic products.   


The operation environment of wearable device would be very serious because it need to contact with human and requirement of signal transmission and power charge frequently. The transient event attacks such as ESD from human and cable or EOS from high current and high voltage power charge would be more complicated and serious. Therefore that the reliability design would be a important consideration for wearable devices. Especially the ESD & EOS protection design for USB TypeC connector must be careful. There are 24 pins totally with each different function in the high integration and convenient reversible plug orientation of USB TypeC connector. If you take traditional single channel TVS protection device for so many pins application. It would suffer huge PCB space and high BOM cost. The wearable device would be more bulky to make customers feel uncomfortable. For this reason that the most suitable protection device for USB TypeC should be multi-channel TVS array. TVS array got multi-channel integration for saving PCB space and cost effective advantage. It could help wearable device to break through the price obstacle into consumer market because of the cost down. As for USB power delivery, because the charge voltage could be 5V,12V and 20V in different charge mode with highest charge current up to 5A. It would recommend to use EOS protection device for VBUS pin for USB TypeC power delivery. The duration time of EOS is longer than ESD. The EOS event would be easy took place to lead to serious burning of electronic product at power charging such as smartphone. Hence that known smartphone maker would execute EOS protection design and standard test for their products. At present that EOS test standard would refer to IEC61000-4-5 with voltage waveform 1.2/50us and current waveform 8/20us.   


Amazing Microelectronic Company have focused on electronic ESD/EOS protection design for over ten years and developed 8 channel TVS array AZ1043-08F by self patent for wearable USB TypeC connector application. The dimension of AZ1043-08F is only 3.8mm x 1.0mm x 0.5mm. AZ1043-08F has not only 0.5pF signal to ground capacitance but also only 0.04pF crosstalk capacitance for avoiding jitter issue. That's why it can applied for USB TypeC high speed signal for signal integrity. As for protection ability, AZ1043-08F can pass the test of ESD standard IEC61000-4-2 at contact 12kV & air 15kV. It also posses 5A protection level of EOS standard IEC61000-4-5. AZ1043-08F got only 9V clamping voltage at 17A TLP current by the measurement of Transmission Line Pulsing System. That's why AZ1043-08F could protect controller IC with advanced semiconductor process and pass the strict direct pin injection ESD test easily. Amazing Microelectronic Company have also released AZ3105-01F/AZ4512-01F/AZ4520-01F ESD/EOS protection device of DFN1610 package series for power delivery 5V/12V/20V application. The DFN1610 package has only 1.6mm x 1.0mm x 0.5mm dimensions and great ESD protection level over contact 30kV & air 30kV of IEC61000-4-2. Furthermore that its best EOS protection level can up to 80A of IEC61000-4-5. Therefore this DFN1610 package series can provide USB TypeC charging port for best ESD/EOS protection.


Figure 1: The TLP clamping voltage I/V curve of ESD protection device AZ1043-08F for USB TypeC high speed signal application.

Figure 1: The TLP clamping voltage I/V curve of ESD protection device AZ1043-08F for USB TypeC high speed signal application.


Figure 2: The Vbus EOS protection devices for USB TypeC charging.

Figure 2: The Vbus EOS protection devices for USB TypeC charging.

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