B72220T2381K105

B72220T2381K105 is a general purpose medium range varistor and transient suppressor device, mainly used for power-line over-voltage protection. It belongs to the family of transient voltage suppression (TVS) devices which also include transient-voltage-suppressed metal oxide varistors (MOVs) and it is designed to protect sensitive semiconductor components from voltage spikes on industrial power-line circuits.

Application Field

B72220T2381K105 is used for the protection of electronic circuits from transients caused by electrical over-voltage (EOS) or electrostatic discharge (ESD) . It can be used for protection in equipment subjected to complex industrial environments with high electromagnetic compatibility, such as industrial controllers, PLC or motor control systems, automation or process control equipment, medical and other critical systems, etc. In addition, it is suitable for protection against surges in consumer equipment such as TVs, home computers or game consoles.

Working Principle

A varistor operates by clamping the voltage in order to protect the circuit from over-voltage events. When a voltage spike occurs, the voltage across the device increases to a level which is known as the peak clamping voltage. When this voltage is exceeded, the varistor begins to limit the voltage across the device. This process is called the “crowbar effect” and is based on the transition from a forward to a reverse bias of the device.

The main components of a varistor are a ceramic component, a metal oxide component, and two electrodes. The ceramic component acts to increase the capacitance whilst the metal oxide component stores energy and becomes electrically conductive at a certain threshold voltage (Vbr). At this point, the current begins to flow through the varistor and it starts to clamp the voltage.

The capacitive section of the varistor is designed so that as the voltage across the device rises, the current increases exponentially. As the current reaches the maximum allowed by the device, the voltage across the varistor stops increasing and the peak clamping voltage is reached. This process of clamping Voltage occurs very quickly, usually complete in a few microseconds.

The peak current of the varistor is set at a value such that it will not damage the circuit in the event of an over-voltage condition. This also limits the peak voltage across the varistor which is known as the holding voltage, Vh. Varistors are designed to operate safely with a peak current which is below the flashover voltage of the device.

The transient over-voltage protection offered by B72220T2381K105 reduces the risk of damage to sensitive semiconductor components vulnerable to voltage spikes or surges. The device also helps to reduce possible high-frequency interference in industrial systems, which may otherwise lead to errors in data transmission or false triggering of the system.