The existence of the resistor can ensure the safety of the circuit, so the resistor is an important component. The chip varistor is one of the common resistors. How much do you know about the working principle of the chip varistor? Where is the chip varistor used? ?The following small series will take you to find out.

Chip Varistors

Introduction to the working principle of chip varistor

SMD varistor is a varistor in SMD package. The overvoltage device varistor developed and produced by Collector is divided into plug-in varistor and SMD varistor in the form of packaging. In addition to varistor and gas Discharge tubes are used in series for lightning surge protection, and can also be used for electrostatic protection of various electronic/electrical equipment. SMD varistors are suitable for handheld electronic products with high integration due to their smaller package size. electrostatic protection.

From the above introduction, it is not difficult for engineers to see that the chip varistor is actually a small packaged overvoltage/anti-static circuit protection device. After understanding the role of the chip varistor, let's understand the application of the chip varistor together. Due to the variety of specifications and sizes of SMD varistors, from handheld electronics to industrial equipment, I/O ports (RS232, USB, PS2, VGA, audio) on motherboards and laptops, set-top boxes, MP3 players devices, DVD players are inseparable from the protection of SMD varistors.

Chip Varistors

Where is the chip varistor used?

It is equivalent to a variable resistor, which is connected in parallel in the circuit. When the circuit is in normal use, the impedance of the varistor is very high and the leakage current is very small, which can be regarded as an open circuit and has little effect on the circuit. But when a very high surge voltage comes, the resistance value of the varistor drops instantly (its resistance value can change from MΩ (megaohm) level to mΩ (milliohm) level), so that it can flow through a large current, while clamping the overvoltage at a certain value. Since the surge withstand capability of a varistor depends on its physical size, it is possible to obtain different surge current values.

The biggest feature of the varistor is that when the voltage applied to it is lower than its threshold UN, the current flowing through it is extremely small, which is equivalent to a closed valve. When the voltage exceeds UN, its resistance value become smaller, so that the current flowing through it surges without changing the influence on other circuits, thereby reducing the influence of overvoltage on subsequent sensitive circuits. Using this function, the abnormal overvoltage that often occurs in the circuit can be suppressed, and the circuit can be protected from the damage of the overvoltage.

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