In summary, Metal Oxide Varistors are high energy devices designed to protect against overvoltage events. They are normally found protecting the AC line feeding an item. Smaller types, frequently referred to as Varistors, protect circuitry deeper inside an application at the PC board level. Thermally protected TMOVs, which disconnect the power source when an MOV fails offer the designer a way to lessen the chances of catastrophic damage. The TMOV is also available in an iTMOV style which features a third lead from the MOV/fuse junction for monitoring. A wide variety of sizes and mounting styles, from surface mount devices and radial leaded MOVs to screw terminal industrial MOVs, are offered to accommodate a wide assortment of applications. Factors to consider when selecting an MOV for an application are; the continuous voltage rating, the physical size of the device, the energy and peak current rating, maximum clamping voltage and the Varistor voltage. It should be remembered that the continuous voltage rating should be 10% to 20% higher than the maximum circuit voltage. The physical size of the MOV depends on the transient energy or current expected, or the required clamping voltage. Finally, the MLN Surge Array™ offers a 1206 package surface mount device containing four MLVs. Available in 5.5V, 9V, 14V and 18V ratings, the MLN has an inherent capacitance that can provide additional filtering to the DC line. The 1206 package also offers considerable PC board space savings over individual MOVs.