MOV Varistor vs TVS Diode - Design guide

Pefey's picture

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Joined: Dec 12, 2019

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MOV Varistor vs TVS Diode - Design guide
January 24, 2020 - 3:45pm

Hey people,

I have an SMPS circuit operating on 220V AC mains on the input side. Now, to suppress surge I have seen many designs using a MOV. But the one in my hand has a TVS diode in place of MOV, can some one tell the pros and cons of using TVS diode instead of MOV?

Also I have few circuits in whcih they have used an MOV and TVS diode in parallel, why is that ? 

Debasis Parida's picture

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Pros of MOV are Easy integration, conducts more current compared to TVS diodes, Higher clamping voltage and Response time is less compared to Spark Gap.The Cons of MOV are, it Cannot handle high energies like lightning and applying too much energy causes damage to MOVs.

 

Sourav Gupta's picture

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Mov requires fuses... That would be blown up during surges.

But tvs do not requires fuses and could not handel too much current.

jaksonlee's picture

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A varistor is a device whose resistance varies with the voltage across its terminals, but in a non-linear relationship. A few electrical devices exhibit this behavior, but the term “varistor” is reserved for components that dissipate energy in a solid material and not in a junction.

The ability to protect sensitive circuit parts from high transient voltages is the same function a TVS diode provides. There are notable differences comparing a varistor vs TVS diode which we will be examining.

Varistors are bidirectional components suitable for both AC and DC circuits. They come in different design packages. The most popular design, the radial disc, closely resembles a capacitor but should not be confused with one.