824540121 Circuit Protection

TVS - Diodes

Transient voltage suppressor (TVS) diodes are a special form of diode, that can be used in conjunction with complementary metal-oxide-semiconductor (CMOS) integrated circuits (also known as ICs) to protect them from electrical overstress (EOS). They are ideal for protecting equipment from high voltage transients, electrostatic discharge, electrical noise, and ground-bounce, that can lead to system failure.

TVS diodes are designed to have a high breakdown voltage rating, with the majority of them ranging from 5V to 500V, allowing them to protect a circuit from a wide variety of over voltage events. The low capacitance ratings on some TVS diodes also allow them to be used in low speed circuitry, which helps to prevent accuracy degradation in signal interpretation.

When selecting a TVS diode an engineer will need to consider the application field and working principle that is required. For example, an ESD rated diode needs to be able to safely absorb static electricity in order to protect the IC. A reverse polarity diode is designed to protect from high voltage transient events, such as lightning strikes, which generally require a higher breakdown voltage rating. Finally, a high power TVS diode needs to be selected if it is going to be used to protect an inductive load, as these types of loads can generate large voltage transients.

TVS diodes are available in a wide variety of package options, including surface mount, through hole, axial lead, and radial lead which are generally used for automated assembly processes. The most popular packages for use in EMC and ESD applications are the SOT-23, SMA, and SOT-223 packages, as they are small and have a low inductance rating.

The operating principle of a TVS diode is fairly simple. When a high voltage transient is applied to the diode, the diode will conduct current, thus diverting the transient away from the IC or load. When the voltage has passed and the diode returns back to its non-conductive state, the current across the diode is cut off and the load can no longer be affected by the transient.

TVS diodes are used in a variety of applications, such as automotive systems, industrial control systems, consumer electronics, telecommunications, and military and aerospace systems, in order to protect against damaging voltage transients. Their small size and wide range of packages make them ideal for use in a wide variety of electronic systems.