MOV-20D821K

TVS diodes, such as MOV-20D821K, are robust transient voltage suppressors (TVSs) in an SMB package. They operate similar to a Zener diode in that they have the ability to protect circuits from the effects of transient over-voltages. MOVs are solid state devices that absorb and dissipate large amounts of energy over a short period of time when the voltage over-runs a defined limit. Therefore, they can absorb and dissipate enough energy to protect circuits from a wide variety of transient over-voltages.

MOV-20D821K is a 20VDC unidirectional type for surface mount applications. It has a voltage range of 5VDC to 20VDC, with a maximum transient over-voltage suppression rating of 18V. It has a standoff voltage of 17.4V, a 3.82V reference voltage, and a 5% aging rate. It has a maximum current rating of 2.0A and a peak pulse power rating of 600W (10/1000μs).

Application Field

MOV-20D821K TVSs are primarily used in electronic circuits and systems that are prone to inductive switching, electrostatic discharge (ESD), lightning, RF, and other transients. It is an ideal choice for PCBs used in industrial systems and other environments where transient over-voltage protection is needed. These TVS devices are commonly used in a variety of applications, including: telecom systems, automotive electronics, military aerospace, computers, cable TV and consumer electronics.

Working Principle

The MOV-20D821K TVS has an intrinsic special interface between two plates, separated by a capacitive material. When a transient over-voltage occurs, the current travels through the material, creating an electric field that is proportional to the transient over-voltage magnitude. The electric field causes the material to conduct an amount of current that is directly related to the size of the voltage spike. This internal current is then diverted or dissipated as heat, protecting the circuit.

This device also has an internal thermal fuse that is designed to protect against possible thermal runaway due to excessive power dissipation. When the device reaches a temperature of 125°C, the fuse is triggered, ensuring that the MOV-20D821K is not damaged due to high junction temperatures.

TVS diodes, such as the MOV-20D821K, provide reliable protection against a variety of transient over-voltage events. They are small, inexpensive, and require no external components for operation. They also have a fast response time and can absorb large amounts of energy.