White Paper: Electronics & Computers
Transient Suppression at Different Interfaces
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This White Paper presents real-world examples of filtering and suppression techniques across asymmetrical, symmetrical, and power interfaces. Using Würth Elektronik components such as ferrites, capacitors, varistors, and TVS diodes, it goes beyond theory with step-by-step calculations and interface-specific recommendations.
Engineers aiming to develop EMC-compliant systems will find practical value in how signal conditions are directly linked to component selection and design decisions based on measurements.
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Overview
The whitepaper on transient suppression at different interfaces discusses the critical role of filter circuits in protecting electronic devices from electromagnetic interference (EMI) and transient overvoltage. As the number of electronic devices connected to public power grids and data networks increases, the need for effective measures to prevent mutual interference becomes paramount.
The document categorizes interfaces into three main types: grid interfaces (230 V mains connections), asymmetrical signal interfaces, and symmetrical signal interfaces. Grid interfaces involve the connection between the power grid and consumer equipment, where line filters are employed to attenuate interference emissions from devices into the power grid and to protect devices from grid interference. Signal interface filters, designed for lower operating currents and voltages, differ in their requirements based on the type of signal transmission—either symmetrical (balanced) or asymmetrical (unbalanced).
The whitepaper emphasizes that while symmetrical interfaces generally exhibit lower interference emissions and higher immunity, they are still susceptible to transient interference signals, differential-mode interference, and common-mode interference. The document provides circuit diagrams and practical examples to illustrate the structure of various interface filters, facilitating easy application to different network or signal interfaces.
A specific focus is placed on asymmetrical signal interfaces, which typically have higher interference emissions and immunity requirements compared to balanced interfaces. The paper includes a detailed analysis of a filter circuit designed for unbalanced signal interfaces, considering a digital signal with specific voltage and frequency parameters.
Additionally, the document addresses transient suppression, detailing the maximum permissible leakage current on protective earth (PE) according to relevant standards. It also includes calculations for energy consumption and power loss in varistors used for transient suppression, providing formulas to determine the energy absorbed by the varistor during surge events.
In conclusion, the whitepaper serves as a comprehensive guide to understanding the principles of transient suppression and EMI filtering for both data and power interfaces. It highlights the importance of these measures in ensuring the reliable operation of electronic devices in increasingly complex electrical environments, offering practical insights and examples for implementation.