What are Transient Voltage Suppressor Diodes?

Transient voltage suppressor (TVS) diodes are semiconductor devices that provide protection from voltage transients or spikes in both positive and negative polarities. They are used to protect sensitive electronic circuits and components from damage due to overvoltage transients.

Working Mechanism of TVS Diodes

A TVS diode works on the principle of avalanche breakdown. It remains in the high-impedance, off-state under normal operating voltages, allowing signals and power to pass through unaffected. When the differential Transient Voltage Suppressor Diodes between the device's anode and cathode exceeds its rated breakdown voltage however, it undergoes avalanche breakdown and enters a low-impedance, on-state.In this state, it acts like a short circuit and clamps the excessive voltage by conducting current through itself to the ground or a power rail, thereby limiting the transient voltage that reaches the protected circuitry. This clamping or crowbar action helps divert and shunt away damaging voltage spikes.

Factors Influencing Breakdown Voltage

The avalanche breakdown voltage of a TVS diode depends on several factors like the diode's physical dimensions, doping concentration, temperature and rate of rise of the applied voltage pulse. Heavily doped diodes have lower breakdown voltages while larger sized devices with higher doping concentrations can handle higher transient voltages.Increasing temperature reduces the diode's breakdown voltage as well. Higher rates of voltage rise induce localized heating within the semiconductor junction, lowering its breakdown point. Manufacturers typically specify the TVS diode's characteristics at specified pulse durations and temperatures.

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