Electromagnetic Compatibility (EMC) Design and Test Case Analysis

483 Pages·2019·18.899 MB·English

by  Junqi Zheng

Electromagnetic Compatibility (EMC)
Design and Test Case Analysis
0004244330.INDD 1 2/5/2019 4:02:42 PM
Electromagnetic Compatibility (EMC)
Design and Test Case Analysis
Junqi Zheng is the Vice Chairman of IEC/CISPR, secretary‐general of the Chinese National
Radio Interference and Standardization Technical Committee, and deputy director of the
EMC Center of Shanghai Electric Apparatus Research Institute. This famous EMC expert
in China has long been engaged in the research of theory and engineering, and he has
rich practice experience in the EMC engineering field. His research achievements
include EMC design methods, test methods and limits, and EMC diagnostic methods in
various types of products, including medical, industrial, military, and automotive. He is
the founder of the EMC design risk evaluation approach, which is the design
methodology that can be adopted by an R&D department.
The book features:
EMC Testing and Design Analysis Cases, 2006
EMC Design Analysis and Risk Evaluation of Electronics Products, 2008

0004244330.INDD 3 2/5/2019 4:02:42 PM
This edition first published 2019 by John Wiley & Sons Singapore Pte. Ltd under exclusive licence granted by
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The right of Junqi Zheng to be identified as the author of this work has been asserted in accordance with law.
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Library of Congress Cataloging‐in‐Publication Data
Names: Zheng, Junqi, 1975– author.
Title: Electromagnetic Compatibility (EMC) Design and Test Case Analysis
Other titles: Electromagnetic compatibility design and test case analysis
Description: Hoboken, NJ : Wiley, 2019. | Includes bibliographical references and index. |
Identifiers: LCCN 2018046968 (print) | LCCN 2018056375 (ebook) | ISBN 9781118956854 (Adobe PDF) |
ISBN 9781118956830 (ePub) | ISBN 9781118956823 (hardcover)
Subjects: LCSH: Electromagnetic compatibility. | Electromagnetic interference.
Classification: LCC TK7867.2 (ebook) | LCC TK7867.2 .Z44 2019 (print) | DDC 621.38–dc23
LC record available at https://lccn.loc.gov/2018046968
Cover design: Wiley
Cover image: © Brostock/Getty images
Set in 10/12pt Warnock by SPi Global, Pondicherry, India
10 9 8 7 6 5 4 3 2 1
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v
Contents
Preface xi
Exordium xv
Introduction xix
1 The EMC Basic Knowledge and the Essence of the EMC Test 1
1.1 W hat Is EMC? 1
1.2 C onduction, Radiation, and Transient 2
1.3 T heoretical Basis 4
1.3.1 Time Domain and Frequency Domain 4
1.3.2 The Concept of the Unit for Electromagnetic Disturbance, dB 5
1.3.3 The True Meaning of Decibel 6
1.3.4 Electric Field, Magnetic Field, and Antennas 9
1.3.5 Resonance of the RLC Circuit 17
1.4 C ommon Mode and Differential Mode in the EMC Domain 21
1.5 E ssence of the EMC Test 23
1.5.1 Essence of the Radiated Emission Test 23
1.5.2 Essence of the Conducted Emission Test 25
1.5.3 Essence of the ESD Immunity Test 29
1.5.4 Essence of the Radiated Immunity Test 30
1.5.5 Essence of the Common‐Mode Conducted Immunity Test 32
1.5.6 Essence of the Differential‐Mode Conducted Immunity Test 34
1.5.7 Differential‐Mode and Common‐Mode Hybrid Conducted Immunity Test 35
2 Architecture, Shielding, and Grounding Versus EMC of the Product 37
2.1 Introduction 37
2.1.1 Architecture Versus EMC of the Product 37
2.1.2 Shielding Versus EMC of the Product 38
2.1.3 Grounding Versus EMC of the Product 40
2.2 Analyses of Related Cases 41
2.2.1 Case 1: The Conducted Disturbance and the Grounding 41
2.2.2 Case 2: The Ground Loop During the Conducted Emission Test 46
2.2.3 Case 3: Where the Radiated Emission Outside the Shield Comes From 49
2.2.4 Case 4: The “Floating” Metal and the Radiation 52
2.2.5 Case 5: Radiated Emission Caused by the Bolt Extended Outside the Shield 55
2.2.6 Case 6: The Compression Amount of the Shield and Its Shielding Effectiveness 59
vi Contents
2.2.7 Case 7: The EMI Suppression Effectiveness of the Shielding Layer Between the
Transformer’s Primary Winding and Secondary Winding in the Switching‐Mode
Power Supply 62
2.2.8 Case 8: Bad Contact of the Metallic Casing and System Reset 68
2.2.9 Case 9: ESD Discharge and the Screw 70
2.2.10 Case 10: Heatsink Also Affects the ESD Immunity 71
2.2.11 Case 11: How Grounding Benefits EMC Performance 72
2.2.12 Case 12: The Heatsink Shape Affects Conducted Emissions
from the Power Ports 76
2.2.13 Case 13: The Metallic Casing Oppositely Causes the EMI Test Failed 82
2.2.14 Case 14: Whether Directly Connecting the PCB Reference Ground
to the Metallic Casing Will Lead to ESD 88
2.2.15 Case 15: How to Interconnect the Digital Ground and the Analog Ground
in the Digital‐Analog Mixed Devices 94
3 EMC Issues with Cables, Connectors, and Interface Circuits 101
3.1 I ntroduction 101
3.1.1 Cable Is the Weakest Link in the System 101
3.1.2 The Interface Circuit Provides Solutions to the Cable Radiation Problem 102
3.1.3 Connectors Are the Path Between the Interface Circuit and the Cable 103
3.1.4 The Interconnection between the PCBs Is the Weakest
Link of the Product EMC 104
3.2 A nalyses of Related Cases 107
3.2.1 Case 16: The Excessive Radiation Caused by the Cabling 107
3.2.2 Case 17: Impact from the Pigtail of the Shielded Cable 110
3.2.3 Case 18: The Radiated Emission from the Grounding Cable 113
3.2.4 Case 19: Is the Shielded Cable Clearly Better than the Unshielded Cable? 117
3.2.5 Case 20: Impacts on ESD Immunity of the Plastic Shell Connectors
and the Metallic Shell Connector 124
3.2.6 Case 21: The Selection of the Plastic Shell Connector and the ESD Immunity 126
3.2.7 Case 22: When the Shield Layer of the Shielded Cable Is Not Grounded 128
3.2.8 Case 23: The Radiated Emission Problem Brings Out Two EMC Design
Problems of a Digital Camera 131
3.2.9 Case 24: Why PCB Interconnecting Ribbon Is So Important for EMC 138
3.2.10 Case 25: Excessive Radiated Emission Caused by the Loop 144
3.2.11 Case 26: Pay Attention to the Interconnection and Wiring Inside the Product 149
3.2.12 Case 27: Consequences of the Mixed Wiring Between Signal Cable
and Power Cable 151
3.2.13 Case 28: What Should Be Noticed When Installing the Power Filters 155
4 Filtering and Suppression for EMC Performance Improvement 161
4.1 Introduction 161
4.1.1 Filtering Components 161
4.1.2 Surge Protection Components 167
4.2 Analyses of Related Cases 173
4.2.1 Case 29: The Radiated Emission Caused by a Hub Exceeds the Standard Limit 173
4.2.2 Case 30: Installation of the Power Supply Filter and 
the Conducted Emission 178
Contents vii
4.2.3 Case 31: Filtering the Output Port May Impact the Conducted
Disturbance of the Input Port 182
4.2.4 Case 32: Properly Using the Common‐Mode Inductor to Solve
the Problem in the Radiated and Conducted Immunity Test 187
4.2.5 Case 33: The Design of Differential‐Mode Filter
for Switching‐Mode Power Supply 190
4.2.6 Case 34: Design of the Common‐Mode Filter for Switching‐Mode
Power Supply 196
4.2.7 Case 35: Whether More Filtering Components Mean
Better Filtering Effectiveness 203
4.2.8 Case 36: The Events Should Be Noticed When Positioning the Filters 208
4.2.9 Case 37: How to Solve Excessive Harmonic Currents
of Switching‐Mode Power Supply 211
4.2.10 Case 38: Protections from Resistors and TVSs on the Interface Circuit 213
4.2.11 Case 39: Can the Surge Protection Components
Be in Parallel Arbitrarily? 218
4.2.12 Case 40: Components in Surge Protection Design Must Be Coordinated 224
4.2.13 Case 41: The Lightning Protection Circuit Design and the Component
Selections Must Be Careful 226
4.2.14 Case 42: Strict Rule for Installing the Lightening Protections 227
4.2.15 Case 43: How to Choose the Clamping Voltage
and the Peak Power of TVS 230
4.2.16 Case 44: Choose the Diode for Clamping or the TVS for Protection 232
4.2.17 Case 45: Ferrite Ring Core and EFT/B Immunity 235
4.2.18 Case 46: How Ferrite Bead Reduces the Radiated Emission
of Switching‐Mode Power Supply 238
5 Bypassing and Decoupling 243
5.1 Introduction 243
5.1.1 The Concept of Decoupling, Bypassing, and Energy Storage 243
5.1.2 Resonance 244
5.1.3 Impedance 248
5.1.4 The Selection of Decoupling Capacitor and Bypass Capacitor 249
5.1.5 Capacitor Paralleling 251
5.2 A nalyses of Related Cases 253
5.2.1 Case 47: The Decoupling Effectiveness for the Power Supply
and the Capacitance of Capacitor 253
5.2.2 Case 48: Locations of the Ferrite Bead and Decoupling Capacitor
Connected to the Chip’s Power Supply Pin 258
5.2.3 Case 49: Producing Interference of the ESD Discharge 263
5.2.4 Case 50: Using Small Capacitance Can Help Solve
a Longstanding Problem 266
5.2.5 Case 51: How to Deal with the ESD Air Discharge Point
for the Product with Metallic Casing 268
5.2.6 Case 52: ESD and Bypass Capacitor for Sensitive Signals 270
5.2.7 Case 53: Problems Caused by the Inappropriate Positioning
of the Magnetic Bead During Surge Test 273
5.2.8 Case 54: The Role of the Bypass Capacitor 275
viii Contents
5.2.9 Case 55: How to Connect the Digital Ground and the Analog Ground
at Both Sides of the Opto‐Coupler 278
5.2.10 Case 56: Diode and Energy Storage, the Immunity of Voltage Dip,
and Voltage Interruption 282
6 PCB Design and EMC 289
6.1 Introduction 289
6.1.1 PCB Is a Microcosm of a Complete Product 289
6.1.2 Loops Are Everywhere in PCB 289
6.1.3 Crosstalk Must Be Prevented 290
6.1.4 There Are Many Antennas in the PCB 291
6.1.5 The Impedance of the Ground Plane in PCB Directly Influences
the Transient Immunity 291
6.2 Analyses of Related Cases 293
6.2.1 Case 57: The Role of “Quiet” Ground 293
6.2.2 Case 58: The Loop Formed by PCB Routing Causes Product Reset During
ESD Test 298
6.2.3 Case 59: Unreasonable PCB Wiring Causes the Interface Damaged by
Lightning Surge 303
6.2.4 Case 60: How to Dispose the Grounds at Both Sides
of Common‐Mode Inductor 305
6.2.5 Case 61: Avoid Coupling When the Ground Plane and the Power Plane
Are Poured on PCB 309
6.2.6 Case 62: The Relationship Between the Width of PCB Trace and the Magnitude
of the Surge Current 314
6.2.7 Case 63: How to Avoid the Noise of the Oscillator Being Transmitted
to the Cable Port 317
6.2.8 Case 64: The Radiated Emission Caused by the Noise
from the Address Lines 319
6.2.9 Case 65: The Disturbance Produced by the Loop 324
6.2.10 Case 66: The Spacing Between PCB Layers and EMI 329
6.2.11 Case 67: Why the Sensitive Trace Routed at the Edge of the PCB Is Susceptible
to the ESD Disturbance 334
6.2.12 Case 68: EMC Test Can Be Passed by Reducing the Series Resistance
on the Signal Line 338
6.2.13 Case 69: Detailed Analysis Case for the PCB Design of Analog‐Digital
Mixed Circuit 339
6.2.14 Case 70: Why the Oscillator Cannot Be Placed on the Edge of the PCB 357
6.2.15 Case 71: Why the Local Ground Plane Needs to Be Placed Under
the Strong Radiator 360
6.2.16 Case 72: The Routing of the Interface Circuit and the ESD Immunity 363
7 Components, Software, and Frequency Jitter Technique 367
7.1 Components, Software, and EMC 367
7.2 Frequency Jitter Technique and EMC 368
7.3 Analyses of Related Cases 368
7.3.1 Case 73: Effect on the System EMC Performance from the EMC Characteristics
of the Component and Software Versus Cannot Be Ignored 368
Contents ix
7.3.2 Case 74: Software and ESD Immunity 371
7.3.3 Case 75: The Conducted Emission Problem Caused by Frequency
Jitter Technique 373
7.3.4 Case 76: The Problems of Circuit and Software Detected by Voltage Dip
and Voltage Interruption Tests 379
Appendix A EMC Terms 381
Appendix B EMC Tests in Relevant Standard for Residential
Product, Industrial, Scientific, and Medical Product, Railway Product, and Others 385
Appendix C EMC Test for Automotive Electronic and Electrical Components 405
Appendix D Military Standard Commonly Used for EMC Test 429
Appendix E EMC Standards and Certification 455
Further Reading 467
Index 469
xi
Preface
The majority of domestic electromagnetic capacity books have a common defect, which is the
lack of connections between design and testing. The discussion of the approach and tech-
niques of EMC design should be based on EMC testing, not only because the first challenge of
EMC design is the EMC test but also because those key factors like interference source, receiv-
ing antenna, and equivalent radiated antenna, which are critical to EMC analysis, will only
exist during the EMC test. Taking the conducted emission test as an example, its essence is the
voltage across a resistor in the line impedance stabilization network (LISN), when the resist-
ance is fixed, the level of conducted disturbance depends on the current passing through the
LISN resistor. EMC design is to reduce the current flow through the resistor. Possible tests
include the typical immunity test, electrical fast transient/burst (EFT/B) test, big current
injection (BCI) test, and electrostatic discharge (ESD) test, which is a typical common mode
immunity test. The source of disturbance is a common‐mode disturbance, referred to the ref-
erence ground plane, i.e. the reference point of these disturbance sources is the reference
ground plane used in the test, which means that the current generated by the disturbance will
eventually return to the reference ground plate. This is the basic starting point to analyze such
disturbance problems.
Imagine, for the above‐mentioned conducted disturbance test, that during the product test-
ing, that the disturbance current does not flow through the LISN resistor, and at the same time,
for the immunity test, that this disturbance current never passes through the product circuit,
it is certainly very favorable for this product to pass the EMC tests, and this is what product
design needs to consider. Therefore, the EMC design must be started from the EMC test.
Electromagnetic Compatibility (EMC) Design and Test Case Analysis, as a project reference
book, makes a close connection with the EMC test substance, EMC design principles, and
specific product design to narrate EMC design methodology. Highly integrating the practical
and theoretical contents is the biggest characteristic of this book.
The book is divided into seven chapters, in which the basic EMC knowledge is described in
Chapter 1, mainly served for the 2–7 chapters. When readers read those later sections, if some
basic concept is vague and not clearly explained, it can be easily consulted and checked from
Chapter 1. Chapters 2–7 includes cases, which are typical and representative. Case descrip-
tions use the same format: [Symptoms], [Analyses], [Solutions], and [Inspirations]. By analyz-
ing each case, we introduce the practical information about EMC design and diagnostic
technology to the designers to reduce the mistakes made by the designer in the product design
and the diagnostic of EMC problems, and achieve good product EMC performance. At the
same time, illustrating the design principles through EMC cases enables readers to achieve
better understanding on the origin of the design. [Inspirations] section actually sums up the
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xii Preface
problem and highlights related issues. It can be used as a checklist of product EMC design. The
cases are divided into the following six categories:
1) Products’ structural framing, shielding, and grounding versus EMC. For most devices, shield-
ing is necessary. Especially with the increasing frequency in the circuit, relying solely on the
circuit board design often fails to meet EMC standards. Proper shielding can greatly
strengthen EMC performance, but an unreasonable shielding design can not only fail to
play its desired effect but also oppositely cause additional EMC problems. In addition,
grounding will not only help solve the safety problem but is also very important for EMC.
Many EMC problems are caused by an unreasonable grounding design, as the ground
potential is a reference potential of the entire circuit. If the ground is not properly designed,
the ground potential may be unstable, which leads to failed circuits. It may also generate
additional EMI problems. The purpose of the grounding design is to ensure that the ground
potential is as stable as possible, to reduce the voltage drop on the ground, thereby eliminat-
ing the interference.
2) Cables of products, connectors, and interface circuit versus EMC. Cable is always the path,
which gives rise to radiation or bringing in the major disturbance. Because of their length,
the cable is not only the transmitting antenna but also a good receiving antenna. And the
cable has the most direct relationship, with the connector and interface circuit. Good inter-
face circuit design not only can make the internal circuit noise well suppressed, so that there
is no driving source for the transmitting antenna, but can also filter out the cable distur-
bance signal received from outside. Proper connector design of cable and interface circuit
provides a good matching path.
3) Filtering and suppressing. For any devices, filtering and suppressing are key techniques to
resolve electromagnetic interference (EMI). This is because the conductor of the device is
acting as a highly efficient receiving and radiating antenna, and therefore, most of the radi-
ation generated by the device is achieved through a variety of wires, while the external
disturbance is often received by the conductor first, then brought into the device. The goal
of filtering and suppressing is to eliminate these interfering signals on the wire, to prevent
circuit interference signals being transferred onto the wire and then radiated through the
wire, and also to prevent the conductors receiving the disturbance and taking them into
the circuit.
4) Bypass, decoupling, and energy storage. When the device is operating, the signal level of the
clock and data signals pins changes periodically. In this case, decoupling will provide enough
dynamic voltage and current for the components when the clock and data are changing in
normal operation. Decoupling is accomplished by providing a low‐impedance power
supply between the signal and power planes. As the frequency increases, before reaching
the resonant point, the impedance of the decoupling capacitors will decrease, so that the
high‐frequency noise is effectively discharged from the signal line. Then the remained
low‐frequency RF energy will not be affected. Best results can be achieved through storage
capacitors, bypass capacitors, and decoupling capacitors. These capacitance values can be
calculated and obtained by specific formula. In addition, the capacitor insulation material
must be correctly selected, rather than randomly selected based on the past usage and
experience.
5) PCB design versus EMC. Whether the device emits electromagnetic interference or is
affected by outside disturbance, or generates mutual interference between the elects, PCB
is the core of the problem (the component layout or the circuit routing of the PCB), and will
have an impact on the nature of the product overall EMC performance. For example, a
simulated interface connector position will affect the direction of common mode current
flows in, and the path of the routing will affect the size of the circuit loop, these are the key
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