EMC Question of the Week: October 6, 2025
Which of the IV curves shown in the figure describes the behavior of a metal oxide varistor (MOV)?
Answer
The best answer is “b.” Metal oxide varistors are bipolar voltage-limiting devices. The curve labeled (a.) describes the behavior of a device that is voltage-limiting, but not bipolar (for example, a unipolar TVS diode). The curve labeled (c.) describes the behavior of a crowbar device such as a thyristor or a gas discharge tube. The curve labeled (d.) corresponds to a device that is a crowbar device for negative applied voltages and voltage-limiting for positive voltages.
Note that bipolar TVS devices that employ two diodes back-to-back in series exhibit a behavior that closely resembles that of a metal oxide varistor.
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