Transient-voltage-suppression diode

Last updated
TVS diode
Transils-01.jpeg
STMicroelectronics Transil TVS devices
Component type Passive
Working principle avalanche breakdown
Electronic symbol
TVS diode symbols.svg

Top is unidirectional, bottom is bidirectional.

A transient-voltage-suppression (TVS) diode, also transil, transorb or thyrector, is an electronic component used to protect electronics from voltage spikes induced on connected wires. [1]

Contents

Description

The device operates by shunting excess current when the induced voltage exceeds the avalanche breakdown potential. It is a clamping device, suppressing all overvoltages above its breakdown voltage. It automatically resets when the overvoltage goes away, but absorbs much more of the transient energy internally than a similarly rated crowbar device. [2]

Comparison of TVS Components [3]
Component
type
Protection
time
Protection
voltage
Power
dissipation
Reliable
performance
Expected
life
Other
considerations
Avalanche TVS50 ps3−400 VLowYesLongLow power dissipation.
Bidirectional also available.
Thyristor TVS< 3 ns30−400 VNoneYesLongHigh capacitance.
Temperature sensitive.
MOV 10−20 ns> 300 VNoneNoDegradesFusing required. Degrades.
Voltage level too high.
Gas discharge tube > 1 μs60−100 VNoneNoLimitedOnly 50−2500 surges.
Can short power line.
TVS diode as array Siemens NTBBA 40 183 340-100 - LCDA05-3328.jpg
TVS diode as array

A transient-voltage-suppression diode may be either unidirectional or bidirectional. A unidirectional device operates as a rectifier in the forward direction like any other avalanche diode, but is made and tested to handle very large peak currents.

A bidirectional transient-voltage-suppression diode can be represented by two mutually opposing avalanche diodes in series with one another and connected in parallel with the circuit to be protected. While this representation is schematically accurate, physically the devices are now manufactured as a single component.

A transient-voltage-suppression diode can respond to over-voltages faster than other common over-voltage protection components such as varistors or gas discharge tubes. The actual clamping occurs in roughly one picosecond, but in a practical circuit the inductance of the wires leading to the device imposes a higher limit. This makes transient-voltage-suppression diodes useful for protection against very fast and often damaging voltage transients. These fast over-voltage transients are present on all distribution networks and can be caused by either internal or external events, such as lightning or motor arcing.

Transient voltage suppressors will fail if they are subjected to voltages or conditions beyond those that the particular product was designed to accommodate. There are three key modes in which the TVS will fail: short, open, and degraded device. [4]

TVS diodes are sometimes referred to as transorbs, from the Vishay trademark TransZorb.

Combined rail-to-rail diodes (left) and unidirectional TVS diode (right) Combined TVS and rail-to-rail diodes.svg
Combined rail-to-rail diodes (left) and unidirectional TVS diode (right)

Characterization

A TVS diode is characterized by:

See also

References

  1. "Evaluating TVS Protection Circuits with SPICE" (PDF). Power Electronics Technology. 32 (1). Primedia: 44–49. 2006. Archived from the original (PDF) on 2012-05-03.
  2. Dai, S. H.; Peng, J. J.; Chen, C. C.; Lin, C. J.; King, Y. C. (2008-09-25). "Low-Capacitance Low-Voltage Transient Voltage Suppression Circuit by Diode Activated SiGe HBT in SiGe HBT BiCMOS Process" . Extended Abstracts of the 2008 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics. doi:10.7567/ssdm.2008.g-3-5.
  3. TVS/Zener Theory and Design Considerations
  4. "Failure Modes and Fusing of TVS Devices" (PDF). Vishay General Semiconductor. 13 August 2007. Retrieved 8 June 2012.
  5. Dai, S. H.; Peng, J. J.; Chen, C. C.; Lin, C. J.; King, Y. C. (2008-09-25). "Low-Capacitance Low-Voltage Transient Voltage Suppression Circuit by Diode Activated SiGe HBT in SiGe HBT BiCMOS Process" . Extended Abstracts of the 2008 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics. doi:10.7567/ssdm.2008.g-3-5.

Further reading