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Widely regarded as the standard text on EMC, Tim Williams' book provides all the key information needed to meet the requirements of the latest EMC Directive. Most importantly, it shows how to incorporate EMC principles into the product design process, avoiding cost and performance penalties, meeting the needs of specific standards and resulting in a better overall product. As well as covering the very latest legal requirements, the fourth edition has been thoroughly updated in line with the latest best practice in EMC compliance and product design. Coverage has been considerably expanded to include the R&TTE; and Automotive EMC Directives, as well the military aerospace standards of DEF STAN 59-41 and DO160E. A new chapter on systems EMC is included, while short case studies demonstrate how EMC product design is put into practice. Tim Williams has worked for a variety of companies as an electronic design engineer over the last 25 years. He has monitored the progress of the EMC Directive and its associated standards since it was first made public. He now runs his own consultancy specialising in EMC design and test advice and training.

Introduction When designing switch mode power supplies (SMPS), undesirable noise and Electromagnetic Interference (EMI) are always present. Their effects are even more severe as the switching frequency increases, especially in applications requiring the use of small size transformer and capacitors. This application note describes the nature and sources of EMI noise, and the design techniques used to reduce their shortcomings. All the examples of the circuitry used are referred to flyback topology however, they are also applicable to any other common SMPS topology. Noise Sources The most effective way to handle EMI is to minimize its source, then use filters to filter away the remaining noise. Therefore understanding the noise sources will greatly help to reduce the effects of EMI. Noise Generated in the Primary Side of the Switching Regulator In a linear regulator, output voltage regulation is achieved by dissipating the voltage drop in the form of heat. The switching regulator achieves output regulation by switching on and off the output transistor and varying the on time. However, switching the transistor on and off causes the generation of high frequency noise. Primary Voltage and Current Waveforms The Drain–to–Source voltage of the transistor, VDS, has a high dv/dt characteristics. At the same time, the leakage inductance results in voltage spikes and ringing, consequently generating noise due to the high dv/dt as shown in Figure 1 and 2. Typically, the collector or drain of the transistor is connected to the tab of the package. (TO–220, TO247 and etc.) The package’s tab becomes an antenna radiating noise. Its effects become even more severe when a heatsink is added on to it. In some high voltage regulator ICís like the MC3337X Series, a relatively quiet source is connected to the TO–220 tab to helps reduce the related common

Electromagnetic Compatibility Engineering Henry W. Ott Henry Ott Consultants Copyright r 2009 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Daitvers, the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/pemiission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable fur your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of e

ELECTROMAGNETIC COMPATIBILITY IN MICROWAVE ENGINEERING Outline 1.Printed circuit board design 2.Electromagnetic shielding 3.Transients 4.Reverberation camber Common used PCBs •Commonly used PCBs have four layerswhere ICs, modules, and discrete components are mounted on the top and bottom surfaces ,power and ground planes are embedded in the inner two layers, and viasare used as interconnections through layers

Preface Printed Circuit Board Design Techniques for EMC Compliance: A Handbook for Designers, Second Edition, is a significant enhancement to the first edition. The first edition was well received within the engineering community worldwide and was translated into international languages. The intent of the present volume is to expand upon concepts presented in the earlier edition, to justify why a specific design technique works, and to show when it is appropriate for use. Additional techniques based on technological changes within the last few years are also incorporated. These techniques and enhancements are based on questions, comments, and discussions received from engineers around the world. This book presents information never before published within the engineering community, dealing exclusively with printed circuit boards (PCBs). When writing the first edition, it was impossible to anticipate the amount of variations possible, or what the intended audience expected from a book directed toward nondegreed engineers. A thorough understanding of the concepts presented herein will assist during the design and layout process. Note the key word here —"concepts." Printed Circuit Board Design Techniques for EMC Compliance will help minimize the emission or reception of unwanted radio frequency (RF) energy generated by components and circuits, thus achieving acceptable levels of electromagnetic compatibility (EMC) for electrical equipment. The field of EMC consists of two distinct areas: 1. Emissions: Propagation of electromagnetic interference (EMI) from noncompliant devices (culprits) and, in particular, radiated and conducted electromagnetic interference. 2. Susceptibility or immunity: The detrimental effects on susceptible devices (victims) in forms that include EMI, electrostatic discharge (ESD), and electrical overstress (EOS). The primary goal of the engineer is to ensure proper operation and performance of a product when used within an intended electromagnetic environment. These design requirements are in addition to making a product function as desired for use within a specific, end-use environment. Information presented in this guideline is intended for those who design and layout printed circuit boards. EMC and compliance engineers will also find the information presented herein helpful in solving design problems at both the PCB and system level. This book can be used as a reference document for any design project. The focus of this book is strictly on the PCB. Containment techniques (shielding), internal and external cabling, power supply design, and other system-level subassemblies that use PCBs as a subcomponent will not be discussed. Again, as in the first edition, excellent reference material on these aspects of EMC system-level engineering is listed in the References section at the ends of chapters.