Appliance Design - February 2009 - (Page 33)

SHIELDING & EMI Noise Suppression ppliances today must meet global compliance requirements for Electromagnetic Compatibility (EMC), and meeting regulatory compliance is complicated by the ever increasing use and density of electronic components. Within a larger appliance are various circuit components and modules that are generators of electromagnetic interference (EMI), and those that are highly susceptible to EMI noise. Each circuit portion must be individually filtered to suppress EMI, or the appliance product as a whole could fail EMC compliance. (See Fig. 1.) A traditional EMI filter consists of passive components: capacitors, inductors, or resistors used singly, or combined together to form a filter network. A unique threenode capacitor technology called X2Y® can now be employed to routinely replace conventional EMI filter networks with a single component. The X2Y technology can mitigate various noise issues, including radiated emissions, power-plane noise in IC power delivery networks, and susceptibility to audible noise in electronic products. Several www.applianceDESIGN.com Fig. 1. Noise interference example in an appliance. A examples that compare X2Y against conventional EMI filters can illustrate how noise reduction can be achieved to help appliances meet global EMC requirements. New capacitor technology improves performance and reduces component count. Technology difference X2Y capacitors share many of the same characteristics as standard 2-terminal multilayer ceramic capacitors (MLCCs). They are made using the same dielectric, electrode, termination materials, and manufacturing processes as MLCCs and are available in the same voltage, capacitance ratings and sizes as conventional MLCCs. Component pickand-place and soldering equipment handle assembly of X2Y components seamlessly. The main difference between an X2Y and a conventional ceramic capacitor is the internal electrode structure, which results in a three-node, four-terminal capacitor that is more effective for both EMI filtering and IC power bypass applications. (See Fig. 2.) Insertion loss (IL) measured on a microstrip test fixture using a Vector Network Analyzer (VNA) is one measure of filter effectiveness. From the IL data, by dave anthony Dave Anthony is business development manager, X2Y Attenuators, Erie, Pa. applianceDESIGN February 2009 33 http://www.appliancedesign.com

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Appliance Design - February 2009 Contents Editorial Shipments/Forecasts News Watch Force-Sensing Technology Offers Designers an Alternative Approach to Creating Touch-Control Interfaces A Flammable Vapor Sensing Technology that was Originally Developed for use in Water Heaters has Evolved for use in a Broader Array of Applications Latches, Hinges, and Slides Must Reliably Secure Parts Together, Sometimes for Hundreds of Thousands of Cycles. Beyond their Utilitarian Functions, They Can Also Change Consumer Perceptions Elastomeric Electrical Connectors Can Solve Space Constraint Problems in Electronic Products and Provide Some Cost Advantages as Well A Multi-Layer Ceramic Capacitor with a Novel Electrode Design Can Suppress Electromagnetic Interference, Improve Circuit Performance, and Reduce the Number of Needed Components Design Marts Association Report: AHRI Advertisers’ Index

Appliance Design - February 2009

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