Varistor Metal Oxide Varistor Products Page 6 Varistor Metal-Oxide Varistor Products

2017 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 09/14/17 Metal-Oxide Varistors (MOVs) Figure 5 shows the effect of a cloud-to-ground strike: the transient-generating effect is far greater. 100m 1km 10km 11kV 1100 V 110 V Figure 5. Cloud-to-Ground Lightning Strike Figure 6, shows a typical current waveform for induced l ightning disturbances. 100 90 50 10 O 1 T 1 TIME PERCENT OF PEAK VALUE Figure 6. Peak Pulse Current Test Waveform Technological Solutions for Transient Threats Because of the various types of transients and applications, it is important to correctly match the suppression solution to the different applications. Littelfuse offers the broadest range of circuit protection technologies to ensure that you get the proper solution for your application. Please consult our online library of Application Notes and Design Notes for further information on common design issues encountered at Metal Oxide Varistors and Multi-Layered Varistors Varistors are voltage dependent, nonlinear devices which have electrical characteristics similar to back-to- back Zener diodes. They are composed primarily of Z N O with small additions of other metal oxides such as Bismuth, Cobalt, Magnese and others. The Metal Oxide Varistor or "MOV" is sintered during the manufacturing operation into a ceramic semiconductor and results in a crystalline microstructure that allows MOVs to dissipate very high levels of transient energy across the entire bulk of the device. Therefore, MOVs are typically used for the suppression of lightning and other high energy transients found in industrial or AC line applications. Additionally, MOVs are used in DC circuits such as low voltage power supplies and automobile applications. Their manufacturing process permits many different form factors with the radial leaded disc being the most common. Multilayer Varistors or MLVs are constructed of Z N O material similar to standard MOVs, however, they are fabricated with interweaved layers of metal electrodes and supplied in leadless ceramic packages. As with standard MOVs, Multilayers transition from a high impedance to a conduction state when subjected to voltages that exceed their nominal voltage rating. MLVs are constructed in various chip form sizes and are capable of significant surge energy for their physical size. Thus, data line and power supply suppression are achieved with one technology. The following parameters apply to Varistors and/or Multilayer Varistors and should be understood by the circuit designer to properly select a device for a given application. The three Littelfuse technologies described offer a comprehensive choice for the designer. Reviewing the attributes of each can result in a suitable ESD suppression solution for most applications. See the individual data sheets for specific electrical and mechanical information. Introduction to Overvoltage Suppression (continued)

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