The primary threat for which designers will specify TVS diode arrays is Electrostatic Discharge (ESD). Arrays are also useful in protecting against residual lightning energy that is let through by primary lightning protection. This module will focus on the ESD threat. It is important to consider that most electronic equipment will spend 99% of its useful life in environments where it is subject to ESD. ESD can be generated from a wide range of everyday factors such as very dry air, static from plastics, or walking across a floor or carpet, and can be present during every phase of the equipment’s life. Damage can occur during manufacturing and shipping as well as during use by the end customer. ESD causes millions of dollars worth of damage to electrical components, rendering circuit boards non-functional, and corrupting or erasing vital data. Often the damage is not detectable until a malfunction occurs. That could take weeks, months, or even years before an unpredictable and premature breakdown causes a field failure and as such manufacturers find they must invest in ESD protection to stay viable.