ESD Protection Devices (anti-static components)What are ESD Protection Elements? Types of ESD Protection Devices and How They Work

For example, when an electrically-charged human body comes into contact with an interface or other part of an electronic device, static electricity is discharged. This phenomenon is called electrostatic discharge (ESD), and ESD generated from an electrically-charged human body (Human Body Model) can be in the order of several thousand volts. This high voltage pulse enters the electronic device with which the body has come into contact, resulting in a malfunction or destruction of the IC circuits inside it. In order to prevent the destruction of a product or system due to the intrusion of ESD into an electronic device that has been touched, it is necessary to install protection devices that suppress or remove ESD.
For the mechanism of static electricity, materials and environments that are prone to being electrically charged, various charge models, the need for ESD countermeasures, and other information, see "What is Static Electricity? Basic Knowledge and ESD Countermeasures."

As stated previously, ESD is a discharge phenomenon of static electricity that occurs when a charged conductive object touches or draws sufficiently close to another conductive object.

On the other hand, surge is a general term used to refer to transient excessive voltage or excessive current.
Excessive currents that occur when the switch is ON/OFF is called "surge" and excessive voltages and excessive currents that occur due to lightning is called "lightning surge."

Electrostatic discharge (ESD) can occur at all points where an electrical device may come into contact with a person or an object, posing a risk of the destruction of internal components such as ICs. This makes it necessary to use "ESD protection elements"* such as TVS diodes, varistors, or suppressors as ESD countermeasures at these points. (For characteristic differences between ESD protection elements and a comparison of their features, see "Differences Between TVS Diodes, Varistors, and Suppressors" in "Features of TVS Diodes and Differences from Other ESD Protection Elements.")

Typical points that require countermeasures involving ESD protection elements with particularly high response speeds—for example, TVS diodes—are shown below.

See "Usage Example of External I/O Interfaces (USBs/HDMIs) and TVS Diodes" for details.

ESD protection elements include TVS diodes, suppressors, varistors, and arresters. Murata provides various TVS diode products.
TVS diodes are suitable for protecting against transient excessive voltage caused by static electricity (ESD), including, for example, ESD protection of data terminals (such as on USB devices) and power terminals. (See "TVS diode usage examples" on the "TVS Diodes (ESD Protection Devices)" page for details.)

"Differences Between TVS Diodes, Varistors, and Suppressors" in "Features of TVS Diodes and Differences from Other ESD Protection Elements" provides a detailed explanation of the differences between ESD protection elements.

As shown on the figure on the left, ESD enters a device from its external interface, which can easily be touched by hand.
Without an ESD Protection Element, excessive voltage of several thousands of volts (such as ESD) could be applied directly to the IC over the external interface, damaging the IC. ESD Protection Elements protect ICs from being damaged by ESD. As shown in the figure on the right, they are connected between the data line and ground, between the external interface and IC.
In order to provide protection, an ESD Protection Element needs to provide two functions:

TVS diodes are characterized by either low or high capacitance and by high electrostatic discharge capability. They are capable of absorbing a high amount of static electricity on DC power lines and data lines up to 5 Gbps. Murata provides various sizes of products, from size 0402 to size 1006.
"Differences Between TVS Diodes, Varistors, and Suppressors" in "Features of TVS Diodes and Differences from Other ESD Protection Elements" provides a detailed explanation of the differences between ESD protection elements.