The Role Of Varistor

What is the use of varistor? The biggest characteristic of a 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 The value becomes smaller, so that the current flowing through it increases sharply, and the impact on other circuits does not change much, thereby reducing the impact 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.

For example, the power supply circuit of our home color TV uses zinc oxide varistor. The varistor varistor voltage used here is 470V. When the maximum value (non-effective value) of the transient surge voltage exceeds 470V, the voltage The varistor is to reflect his clamping characteristics, pull the excessively high voltage down, and let the subsequent circuit work in a safe range.