What are the roles of Zener diodes and varistors in circuits

What are the roles of Zener diodes and varistors in circuits

Semiconductor devices are electronic devices with conductivity between good conductors and insulators, utilizing the special electrical properties of semiconductor materials to perform specific functions. They can be used to generate, control, receive, transform, amplify signals, and convert energy. Among numerous electronic components, there are Zener diodes and varistors that belong to semiconductor devices.

Let's take a look at the roles of Zener diodes and varistors as semiconductor devices in circuits.

Zener diode

Zener diode, also known as voltage regulator diode, is a crystal diode made of silicon material, belonging to semiconductor devices, with high resistance until the critical reverse breakdown voltage.

When the reverse voltage is lower than the reverse breakdown voltage, the reverse resistance is large and the reverse leakage current is extremely small. When the reverse voltage of the Zener diode in the circuit approaches the critical value of the reverse voltage, the reverse current suddenly increases, which is called breakdown. At this critical breakdown point, the reverse resistance suddenly drops.

Zener diodes in circuits experience reverse breakdown, and when the current changes over a large range, the voltage at both ends of the Zener diode remains basically unchanged, exhibiting voltage stabilization characteristics. They are widely used in voltage regulation power supplies and are mainly used as voltage regulators or voltage reference components in circuits.

Varistor

Varistors are a new type of voltage limiting protective device, made of semiconductor materials and belonging to semiconductor components. They have nonlinear volt ampere characteristics and their resistance values are sensitive to voltage. Within a certain range of current and voltage, the resistance value of varistors changes with the variation of voltage.

When overvoltage occurs in the circuit and current passes through the varistor, the varistor clamps the voltage to a relatively fixed value, absorbing excess current to protect the secondary circuit and other electronic components.

Varistors play a role in suppressing transient overvoltages and providing lightning protection in circuits. They are used in surge suppressors, security systems, motor protection, automotive electronic systems, household appliances, consumer electronics, and more.