In application scenarios where large instantaneous currents flow through current-limiting circuits, or where electrostatic discharge (ESD) may occur, resistors must exhibit excellent pulse-withstanding and surge-withstanding capabilities to ensure stable circuit operation.
I. Core Definitions of Pulse and Surge
Two types of instantaneous overload phenomena in circuit applications require close attention:
Pulse: Refers to high-power, relatively long-duration instantaneous overload with high energy density.
Surge: Typically represented by ESD (electrostatic discharge), characterized by high voltage and extremely short duration.
II. Core Characteristics of Pulse- and Surge-Resistant Resistors
The key advantage of pulse- and surge-resistant resistors is that their resistive element structure remains stable and resistant to damage even under instantaneous high-power shocks or high-voltage strikes, thereby preventing circuit failures caused by resistor breakdown.
In terms of product categories, among surface-mount resistors, thick-film resistors (metal-glaze thick film) offer significantly superior pulse resistance compared to thin-film resistors (metal thin film).
FOSAN has further enhanced the pulse-withstanding performance of its surge-resistant series by optimizing the structural design of thick-film chip resistors. In addition, metal plate current-sensing resistors, constructed from solid metal plate material, deliver exceptional pulse and surge resistance, making them suitable for highly demanding application environments.
III. Snubber Circuits and Key Resistor Selection Criteria
What is a Snubber Circuit?
A snubber circuit is designed to absorb surge energy generated during switching operations, usually connected across components prone to surge voltages. Common snubber circuits include resistor-capacitor series circuits (RC snubbers), diode circuits limiting front-end surge voltages, and others, as indicated by the circled section in the diagram.
Resistor Selection Requirements for Snubber Circuits
In equipment such as switching power supplies, the ON/OFF switching action induces inrush voltages and current transients, causing surges in secondary rectifier diodes. An RC snubber circuit is therefore required to absorb these surge voltages, and the resistors used must possess reliable surge-withstanding properties.
Meanwhile, snubber circuits must effectively suppress noise while minimizing energy loss, so resistor selection must balance performance optimization and operational safety. Based on switching voltage parameters and snubber circuit design, risks of resistor smoking or ignition caused by short circuits in capacitors and semiconductors must be avoided, making flame resistance a critical selection indicator.
For surface-mount power circuit applications, FOSAN specifically recommends the FRS Series Surge-Resistant Thick-Film Chip Resistors, whose performance precisely matches the surge-withstanding and low-loss requirements of snubber circuits, providing robust protection for stable equipment operation.
IV. Empowerment by FOSAN Products
With deep expertise in the resistor industry, FOSAN has built a diversified product portfolio including the FRS Series Surge-Resistant Thick-Film Chip Resistors to address pulse and surge protection needs. Through core technologies such as structural optimization and material upgrading, the products achieve multi-dimensional breakthroughs in pulse resistance, surge resistance, and flame resistance, complying strictly with industry standards. They are widely applicable to switching power supplies, industrial control, consumer electronics, and various other fields.
Moving forward, FOSAN will continue to focus on pain points in circuit protection, driven by technological innovation, to iterate and upgrade environmentally robust and highly reliable resistor products. It will deliver more targeted solutions to global customers, enabling stable operation of electronic equipment under complex working conditions.