Home > Products > Electronics & Electricity > Electronic Components > Other Electronic Components

Varistor

A varistor is an electronic component with a significant non-ohmic current-voltage characteristic. The name is a portmanteau of variable resistor. Varistors are often used to protect circuits against excessive transient voltages by incorporating them into the circuit in such a way that, when triggered, they will shunt the current created by the high voltage away from the sensitive components. A varistor is also known as Voltage Dependent Resistor or VDR. A varistor's function is to conduct significantly increased current when voltage is excessive.

Varistor Pictures

• Dipped Varistor
• SMD Varistor

Varistor List

Good support for Chip Varistor

Suntan is with very good support for Multilayer Metal Oxide Chip Varistor. This products is featured with Low firing, Sliver diffusion, Grain resistance, Electrical properties and it is widely used in cellular telephones and automotive electronic subassemblies.

Standard Operating temperature for this product is -55~ +125°C; Working Voltage is 3.3V--68V and it is Low Leakage Current, ROHS compliant; Sizes including 0402, 0603, 0805, 1206, 1210, 1812, 2220.

Suntan also offer TSV Dip Varistor. Size code: TSV05D, TSV07D, TSV10D, TSV14D, TSV18D, TSV20D, TSV25D, TSV32D, TSV40D; item code: 182K, 152K, 112K, 102K, 911K, 821K, 781K, 751K, 681K, 621K, 561K, 511K, 471K, 431K, 391K, 361K, 331K, 301K, 271K, 241K, 221K, 201K, 181K, 151K, 121K, 101K, 820K, 680K, 560K, 470K, 390K, 330K, 270K, 220K, 180L.

Suntan Dipped Varistor production volume increased

Suntan offer different size of dipped varistor and the production volume is keep increasing. We have sice code 05D, 07D, 09D, 10D, 14D, 18D and 20D and each is with different voltage, varistor Voltage ranges from 18V to 1800V.

Dipped Varistor has fast response to the rapidly rising surge voltage. It with high performance clamping voltage characteristics. So, with these characteristics, it could be applied for Transistor, diode, IC, thyristor and triac semiconductor protection; Surge protection in consumer electronics; Surge protection in industrial electronics; Surge protection in communication, measuring and controller electronics; Surge protection in electronic home appliances and gas and petroleum appliances; Electrostatic discharge and noise spike suppression; Relay and electromagnetic valve surge absorption.

What is a Varistor?

A varistor is a type of resistor with a significantly non-ohmic current-voltage characteristic. The name is a portmanteau of variable resistor*, which is misleading since it is not continuously user-variable like a potentiometer or rheostat, and is not a resistor but in fact a capacitor. Varistors are often used to protect circuits against excessive voltage by acting as a spark gap.

The most common type of varistor is the metal oxide varistor, or MOV. This contains a mass of zinc oxide grains, in a matrix of other metal oxides, sandwiched between two metal plates (the electrodes). The boundary between each grain and its neighbour forms a diode junction, which allows current to flow in only one direction. The mass of randomly oriented grains is electrically equivalent to a network of back-to-back diode pairs, each pair in parallel with many other pairs. When a small or moderate voltage is applied across the electrodes, only a tiny current flows, causes by reverse leakage through the diode junctions. When a large voltage is applied, the diode junctions break down because of the avalanche effect, and a large current flows. The result of this behaviour is a highly nonlinear current-voltage characteristic, in which the MOV has a high resistance at low voltages and a low resistance at high voltages.

If the size of the transient pulse (often measured in joules) is too high, the device may melt, or otherwise be damaged. For example, a nearby lightning strike may permanently damage a varistor.

Important parameters for varistors are response time (how long it takes the varistor to break down), maximum current and a well-defined breakdown voltage. When used in communications lines (such as phone lines used for modems), high capacitance is undesirable since it absorbs high frequency signals, thereby reducing the available bandwidth of the line being protected.