What are Transient Voltage Suppressors?
Transient voltage suppressors (TVS) are electronic devices that protect electronic circuits from sudden voltage spikes or transients. These spikes can occur due to lightning strikes, electrostatic discharge, or switching inductive loads. These voltage spikes can destroy sensitive electronic components, such as integrated circuits, by causing them to fail due to overstress. A TVS device can be added to a circuit to provide a low impedance path to ground during a transient event, limiting the voltage seen by the protected circuit.
TVS devices are available in a variety of packages, including surface mount, axial leaded, and radial leaded. They are commonly made of silicon or zinc oxide and are available in both uni-directional and bi-directional versions. The uni-directional version is designed to protect against voltage spikes in one direction, while the bi-directional version can protect against voltage spikes in either direction.
How Transient Voltage Suppressors Work
A TVS device works by providing a low impedance path to ground during a transient event, limiting the voltage seen by the protected circuit. When a transient voltage exceeds the TVS’s breakdown voltage, the TVS begins to conduct current, shunting the transient voltage to ground. The TVS’s low impedance path to ground causes the voltage seen by the protected circuit to be limited to the TVS’s breakdown voltage. Once the transient voltage has passed, the TVS returns to its high impedance state, allowing normal circuit operation to continue.
Applications of Transient Voltage Suppressors
TVS devices are commonly used to protect electronic circuits from voltage spikes caused by lightning strikes, electrostatic discharge, or switching inductive loads. They can be found in a variety of applications, including power supplies, communication systems, medical equipment, and automotive systems. TVS devices can also be used in combination with other protection devices, such as fuses and overvoltage protection circuits, to provide comprehensive protection for electronic circuits.
Example of Transient Voltage Suppressor Circuit
The above circuit shows an example of a TVS protection circuit. The TVS device is connected in parallel with the protected device, providing a low impedance path to ground during a transient event. The TVS device’s breakdown voltage is chosen to be slightly higher than the maximum voltage seen by the protected device. In this way, the TVS device only begins to conduct when the voltage exceeds the protected device’s maximum voltage rating. The resistor in series with the TVS device limits the current during normal operation, preventing damage to the TVS device. The capacitor in parallel with the TVS device helps to smooth out any high-frequency noise that may be present.
