Background：

In the era of rapid development of mobile Internet, smart phones have become an indispensable communication tool. As a product with high frequency of human-computer interaction, the phone may be damanged by human electrostatic discharge and static electricity. Static electricity damages the USB interface of the mobile phone and will also cause the failure of the USB integrated circuit. Eventually, the phone will fail to charge,crash, reboot, and lose data.

At the same time, in the process of plugging and unplugging the USB port of the mobile phone, it is easy to cause the EOS surge noise of the Vbus power supply. This kind of surge frequency will seriously damage the internal IC of the mobile phone. The hot-pluggability of USB makes it an ESD-sensitive component. Therefore, it is extremely important and necessary to implement ESD protection for mobile phone USB ports.

SOCAY Solution and Electronic Components：

The Solution Notes：

USB makes data transfer between different electronic devices faster and more convenient. As the size of common files continues to increase, high data rates are becoming increasingly important. So in this case, adding any capacitance to the data line may distort the signal waveform and interrupt the digital data transmission. Therefore, the selection of ESD protection devices needs to be very careful. The following is the basic idea of SOCAY FAE engineers to choose ESD protection devices:

1. The USB Vbus side uses a small, high-power ESD device that can withstand surges of 300V or more by （IEC 61000-4-5 1.2/50us-8/20us).

2. The maximum working voltage of ESD at the USB Vbus end is 13.5V, which meet different standards of high-voltage fast charging technology.

3. A small size and high-power ESD with a working voltage of 4.5V is used for secondary protection at Vbat end

4. Other high-speed differential communication line ESD protection, using low inter-pole capacitance 0.35pF, can meet high-speed communication transmission.

SOCAY Electrostatic Discharge Protection Devices：

ESD1~6【SE05VP50N-16】Vrwm：5.0V；Vesd：8KV/15KV；Ct（f=1MHz）：0.35pF；

ESD7【SE13V5202N-20】Vrwm：13.5V；Vesd：30KV/30KV；Ct（f=1MHz）：2000pF；

ESD7【SE4V5700D-32】Vrwm：4.5V；Vesd：30KV/30KV；Ct（f=1MHz）：70pF；

Our FAE engineers analyzed the protection requirements of mobile phone USB ports and proposed ESD protection solutions. The reliability and effectiveness of the solution was verified through real simulations and extensive test data in our EMC lab. The correctness of the circuit solution was verified in a practical application to a customer.