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Zinc OxideVaristors

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Varistors: Voltage-Dependent Protection Devices

A varistor is a non-linear resistance device primarily used to clamp voltage during overvoltage events and absorb excess current, protecting sensitive electronic components. Known as a Voltage Dependent Resistor (VDR), or simply a varistor, this device is made of semiconductor materials. Modern varistors, particularly Zinc Oxide (ZnO) types, are constructed from zinc (Zn) and oxygen (O), classifying them as "II-VI semiconductor oxides."

In Taiwan, varistors are sometimes called "surge absorbers" or "surge suppressors." They act as voltage-limiting devices, using their non-linear characteristics to clamp overvoltage at a fixed value, ensuring the safety of sensitive devices.

JVA - Zinc Oxide Varistors Overview

A varistor is an electronic component whose resistance changes based on the applied voltage. Below are the key features, applications, and specifications of JVA Zinc Oxide Varistors.

JVA Zinc Oxide Varistors Introduction

Zinc oxide varistors are ceramic materials with electrical properties governed by grain-boundary interface states. They exhibit a highly nonlinear current-voltage relationship, where a 5% change in voltage can increase current flow by an order of magnitude or more.

Features of JVA Zinc Oxide Varistors

• Round, leaded varistor element.
• Low leakage current.
• Excellent voltage and energy ratios.
• High clamping voltage performance.
• Low standby power consumption with no follow-on current.

Applications of JVA Zinc Oxide Varistors

• Widely used to protect power and signal-level circuits from dangerous voltage surges.
• Surge protection for communication, measurement, and control electronics.

Key Characteristics:

• Voltage Sensitivity: Reacts to overvoltage by clamping it.
• Current Capacity: Handles significant currents during surges.
• Junction Capacitance: Ranges from hundreds to thousands of picofarads (pF).
• Response Time: Fast, in the nanosecond range, ideal for most overvoltage protection scenarios.

While slower than TVS diodes but faster than gas discharge tubes, varistors are effective in general circuit protection. However, their high capacitance may not suit high-frequency signal lines, particularly in communication circuits, where leakage current must be carefully managed.

Applications and Performance:

Metal Oxide Varistors (MOVs), made from sintered zinc oxide with metal oxide additives, offer excellent protection by limiting surge voltages and absorbing energy pulses. Their cost-effective performance makes them a popular choice for optimizing transient protection in circuit designs.

Features and Use:

• Varistors are voltage-dependent resistors that drastically reduce resistance as voltage increases.
• When installed parallel to equipment, they divert transient surges and prevent overvoltage from damaging the device.
• Manufactured to high standards, MOVs are widely used in telecommunications, industrial, automotive, and consumer markets.

Zinc Oxide Varistors (ZOVs):

ZOVs are critical components in circuits where voltage regulation is essential. Primarily used in protective circuits for voltage-sensitive devices, they ensure that transient surges are bypassed, preventing damage. ZOVs are designed to handle high current during voltage surges and are customized to meet specific customer requirements.

VA - Zinc Oxide Varistors Specifications

Zinc Oxide Varistors