Overvoltage Protection Comparison
TVS Diodes
Transient Voltage Suppressor (TVS) diodes are clamping voltage suppressors that are
constructed with back-to-back PN junctions. During conduction, TVS diodes create a low
impedance path by varying their resistance as voltage is applied across their terminals.
Once the voltage is removed, the diode will turn off and return to its high off-state
impedance.
Advantages
Because TVS diodes are solid state devices, they do not fatigue nor do their electrical
parameters change as long as they are operated within their specified limits. TVS diodes
effectively clamp fast-rising transients and are well suited for low-voltage applications that
do not require large amounts of energy to be shunted.
Restrictions
Because TVS diodes are clamping devices, they have two inherent weaknesses. First, TVS
diodes are both voltage- and current-limited, so careful consideration should be given to
using these in applications that require large amounts of energy to be shunted. Secondly,
as the amount of current flowing through the device increases, so does its maximum
clamping voltage.
Applications
Due to their low power ratings, TVS diodes are not used as primary interface protectors
across Tip and Ring; they are used as secondary protectors that are embedded within a
circuit.
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