How to avoid the USB-C connector from ESD

Fri Apr 28 11:39:06 CST 2023

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How to avoid the USB-C connector from static electricity

Today's consumers have become reliant on mobile devices that use the USB-C communication interface standard, from smartphones and tablets to wearables and laptops. USB ports also double as fast charging ports for most of these devices. As a result, designing protection against electrostatic discharge (ESD) has never been more important.

To handle higher data transfer rates and higher power transfer, the USB Type-C cable and connector standard has been updated to version 2.12 and the USB-PD (Power Transfer) standard has been updated to version 3.1. PD allows charging and powering of devices through the USB interface. The maximum power capacity has been increased from 2.5 W (5 V @ 0.5A) to 100 W (20 V @ 5A) and now to a power range of 240 W (48 V @ 5A). The higher power capacity will open up new powering and charging applications for USB-C, such as gaming laptops, expansion docks, 4K monitors, and PC all-in-ones.

The Type-C connector has 24 pins compared to the 4 pins of the Type-A connector. The signal contact pitch of Type-C connectors is 0.5 mm, and the contact arrangement is very tight.

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While evolving standards have increased data transfer rates and increased charging power, these standards do not directly specify specific methods for protecting the USB interface from external hazards. This article will describe methods to eliminate the possibility of failure due to electrostatic discharge. These techniques are critical to ensuring more reliable and robust products.

Protects USB ports from electrostatic discharge

Electronic circuits exposed to the external environment through cables and connectors, such as USB ports, are potential targets for electrostatic discharge (ESD). ESD shocks can occur through direct human contact or through the air. ESD shocks can be as high as 30 kV or more, have fast rise times, and can melt silicon and wires with currents as high as 30 A. ESD has such high energy that it can lead to complete component failure.

In addition, ESD shocks can cause more subtle damage. ESD-induced currents can cause soft faults, including state changes in logic devices, latch-ups, or unpredictable behavior. This can lead to data stream corruption. Data will need to be retransmitted, which can reduce the data transfer rate. ESD can also lead to potential defects where components are still functional but have degraded and may fail prematurely.

The following figure shows the simulated electrostatic discharge test waveforms specified in IEC 61000-4-2.

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A variety of products are available to protect communication ports from ESD damage. The diagram below shows recommended protection components for USB interface lines with up to 100 W of power supply capability and up to 240 W of extended power supply range. The component used is a transient voltage suppressor (TVS) diode. 

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USB Protection Components Features Benefits:

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By HornmicLink_Henry @230428 11:43