With the expansion of the Internet of Things (IoT), billions of electronic devices are expected to be connected to the network in the future. They will play an important role in our lives, such as consumer devices for home automation, or hidden devices such as those in cars and smart buildings, all of which will be sensitive to electrostatic discharge (ESD). Once the PCB is assembled and installed in the device, the ESD remains one of the main sources of failure. For the ESD protection design of the equipment, the selection of appropriate anti-interference equipment is particularly important.
When engineers design environmental limits such as humidity, temperature, and vibration, ESD is highly impermissible. Therefore, it is best practice to design appropriate anti-interference equipment to circumvent the effects of electrostatic discharge on the equipment. For testing of protective equipment, standards such as IEC 61000-4-2 define the level of protection based on the severity of the discharge voltage in the test.
The impact of ESD on electronic devices.
When the supply line voltage drops, which is widely used to reduce active power consumption, the ESD protection that may exist in the device may also be reduced. Almost all general-purpose ICs are now based on metal-oxide-semiconductor field-effect transistors (MOSFets), and many supply voltage lines are even below 1V. This makes them more sensitive to the transient effects of ESD.
The transient phenomenon of ESD can dissipate quickly without causing any damage, or cause irreparable damage due to the fuse of the interconnect. Therefore, the most practical chip circuit protection devices design the resistor or capacitor in the path of the ground wire connected to the control circuit, so that the ground wire can effectively carry away the electrostatic transient discharge.
Understanding ESD protection devices.
Typically, ESD protection devices are either semiconductor-based transient voltage suppressors (TVS) or ceramic-based varistors. TVS and MLV are fairly mature technologies with similar physical characteristics. In applications with low voltage and low speed signals, TVS or MLV protection can be used. The choice of MLV and TVS diodes is not a major design consideration for permeable currents. Both techniques exhibit some sort of permeable current and are fairly similar.
Select an ESD protection plan.
Due to the way the MLV and TVS are protected against transient surges, engineers can use the TVS and MLV solutions interchangeably in many applications. They are all small in size and can often be placed near MLVs and TVS diodes that could introduce electrostatic discharge from external sources, such as exposed interfaces or charging ports.
Both are very mature technologies due to their wide application and large output, and there is now a trend to reduce the average sales to a comparable and competitive cost level. The capacitance characteristics of MLV can be used for EMI filtering due to better tolerance control, providing better protection for low-loss, high-frequency signals.
Protection of electronic devices against ESD transients is required. As the supply voltage decreases and the data speed increases, the operating conditions determine what form of protection is taken for the product. Insertion loss and parasitic capacitance are becoming more relevant and highly valued considerations. As manufacturing methods have improved, engineers have placed particular emphasis on tolerance control of capacitors when designing ESD protection. Not only does it save costs, but it also saves board space. As more and more devices are connected to the network, it will become increasingly important to extend ESD protection to every device in a wider system, but engineers must also be more comprehensive when designing.