The working voltage of a TVS diode, also known as the Reverse Standoff Voltage (VRWM), is the maximum DC or continuous peak reverse voltage that can be applied to the diode without causing it to conduct significantly. This voltage is the normal operating voltage of the circuit the TVS diode is protecting.
TVS diodes are designed to remain non-conductive below their breakdown voltage, ensuring they do not interfere with the normal operation of the protected circuit. The VRWM is typically chosen to be equal to or slightly higher than the maximum operating voltage of the circuit being protected.
Understanding VRWM
The VRWM is a crucial parameter when selecting a TVS diode. If the voltage across the diode exceeds the VRWM but is below the breakdown voltage (VBR), the diode will ideally not conduct significantly. However, once the voltage reaches the breakdown voltage, the diode rapidly conducts, shunting transient energy away from the protected circuit.
Working Voltage Ranges
The working voltage (VRWM) of TVS diodes varies widely depending on the specific series, power rating, and whether the diode is unidirectional or bidirectional. According to the provided reference from MCC's Non-Automotive TVS diodes, common VRWM ranges include:
- Unidirectional TVS Diodes:
- Ranges such as 5 V ~ 120 V
- Ranges such as 5.8 V ~ 77.8 V
- Bidirectional TVS Diodes:
- Ranges such as 15 V ~ 58 V
- Ranges such as 5.8 V ~ 495 V
This variation highlights that there is no single "working voltage" for all TVS diodes; rather, it is a specification that must be selected based on the requirements of the specific application circuit.
MCC TVS Diode VRWM Examples (from Reference)
Below is a summary table from the reference showing examples of VRWM ranges for different power ratings and configurations:
| PPP (W) | Configuration | VRWM (V) |
|---|---|---|
| 1000 | Uni-dir | 5 ~ 120 |
| 1000 | Uni-dir | 5.8 ~ 77.8 |
| 1500 | Bi-dir | 15 ~ 58 |
| 1500 | Bi-dir | 5.8 ~ 495 |
Note: PPP refers to Peak Pulse Power rating.
Selecting the appropriate VRWM ensures the TVS diode provides effective surge protection without interfering with the circuit's normal operation.
