What Is a TVS Diode?
1 min read
Quick answer
A TVS diode (Transient Voltage Suppressor) is a very fast protection diode that protects a circuit from sudden overvoltage spikes (transients). It's used against lightning, ESD and switching surges.
How Does It Protect?
Normally it's an insulator; when the voltage exceeds a safe limit it starts conducting within nanoseconds, dumping the excess energy to ground and clamping the voltage to a safe level. Once the surge passes it becomes an insulator again.
Difference From a Zener Diode
| Property | Zener | TVS |
|---|---|---|
| Purpose | Voltage regulation | Surge protection |
| Speed | Medium | Very fast |
| Surge energy | Low | High |
Unidirectional and Bidirectional
Unidirectional TVS is used on DC lines, while bidirectional TVS is used on AC or signed signal lines.
Where Is It Used?
On USB/data lines, power inputs, automotive electronics and ESD protection. It's connected in parallel between the line to be protected and ground.
Common Mistakes
- Choosing it too close to the working voltage: the clamping voltage must be above the normal signal, otherwise it conducts continuously.
- Getting the direction wrong: connecting a unidirectional TVS backwards breaks the protection.
- Underestimating the energy rating: large surges need a TVS with enough power.
Frequently Asked Questions
Is a TVS the same as a zener?+
It works similarly, but a TVS is designed to absorb surge energy quickly; it's used for protection, not regulation.
How is a TVS connected?+
In parallel between the protected line and ground; normally it doesn't affect the circuit and conducts only during a surge.
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