The Littelfuse TMOV® and iTMOV® thermally protected varistors represent a new development in integrated circuit protection...

MOV Factory

The material in this application guide has been arranged in 3 parts for easy reference; Section A provides general guidelines on what types of MOV products are best suited for particular environments. Section B explains what Metal Oxide Varistors are and the basic function they perform. And section C helps clarify important information about MOVs for the design engineer, and answers questions that are asked most often.

This application note discusses the two major categories of transient suppressors: a) those that attenuate transients, thus preventing their propagation into the sensitive circuit; and b) those that divert transients away from sensitive loads and so limit the residual voltages.

This application note details the common tests of varistor parameters and describes suitable test methods using simplified test circuits. All tests are performed at 25° C, unless otherwise specified. The test circuits and methods given are intended as a general guide. Since the tests frequently entail high voltages and currents, users must exercise appropriate safety precautions.

This application note discusses the methods that exist to prevent MOVs from reaching combustible temperatures and focuses on the new integrated TMOV varistor thermal fuse technology which reduces part count, saves space and is UL1449 recognized.

This application note illustrates how to design high performance, cost-effective surge protection for equipment connected to AC power lines. The role of gas discharge tube (GDT) surge arresters specifically designed for AC power line protection is also be discussed.