Troubleshooting Switching Power Converters (eBook)

A Hands-on Guide

Sanjaya Maniktala (Autor)

eBook Download: PDF

2011 | 1. Auflage
320 Seiten
Elsevier Science (Verlag)
978-0-08-055125-8 (ISBN)

Infos

Power Supply design is all about detail. And a large part of that detail lies in the practical domain, largely because of the typically small number of microseconds of switching periods involved, and the even smaller tens of nanoseconds of switch transition times --- all these, in effect accentuating various second-order effects, that eventually end up playing prime havoc with normal expectations of how the circuit should behave. So not unsurprisingly, even after reading several books, most readers still find themselves no closer to the ultimate goal of designing an actual power supply.

Sooner or later, all engineers start realizing the hard fact that designing a switching power supply isn't the trivial task it once seemed to be. But even after years of successfully mastering the underlying theory, the ultimate goal of creating a cost-effective, reliable and commercially viable power supply may still remain a distant dream, since success ultimately hinges on experience. That is, in fact, what clearly differentiates a senior and seasoned power supply engineer from the others --- the ability to navigate and surmount a veritable minefield of tricky issues that can only be learned the hard way, by actual hands-on experience on the job.

This book presents practical knowledge the author acquired rather painfully, while working in the trenches for several years in major engineering companies scattered across several continents. This is intended to be the mythical senior engineer's bag of tricks, finally made available in the form of an easy-to-read book on your shelf. This book will make life for the ambitious power supply engineer much simpler --- besides reducing significantly, the rigorous requirement of having to be a senior engineer's prot?g? for years on end, just to gain a small measure of real success in this field.

* A practical presentation that answers the important question: why is my switching converter behaving so differently than what I was expecting on the basis of my paper design? And how do I bridge that huge gap?
* For the first time, a systematic and thorough discussion of troubleshooting switching power supplies.
* Coverage of AC/DC and DC/DC power supplies.
* Bench Evaluation of semiconductor ICs used in power conversion --- describing standard and unusual techniques mastered by the author, while testing similar chips at National Semiconductor.
* Detailed coverage of vital topics that haven't been covered by available sources --- grounding systems, the subtleties of component datasheets, and using instruments and probes effectively.
* Systematic investigation (type of failure mechanism, topology, etc.) and solutions for 5 years of reported power supply issues on a prominent, public web forum. This approach will ensure that engineers will not repeat the same mistakes.
* A unique, readable style: personal and direct, no mystification--- just the plain truth, easily and logically explained, with plenty of pictures, graphs and plots.

---

Power Supply design is all about detail. And a large part of that detail lies in the practical domain, largely because of the typically small number of microseconds of switching periods involved, and the even smaller tens of nanoseconds of switch transition times --- all these, in effect accentuating various "e;second-order"e; effects, that eventually end up playing prime havoc with "e;normal"e; expectations of how the circuit should behave. So not unsurprisingly, even after reading several books, most readers still find themselves no closer to the ultimate goal of designing an actual power supply. Sooner or later, all engineers start realizing the hard fact that designing a switching power supply isn't the trivial task it once seemed to be. But even after years of successfully mastering the underlying theory, the ultimate goal of creating a cost-effective, reliable and commercially viable power supply may still remain a distant dream, since success ultimately hinges on experience. That is, in fact, what clearly differentiates a senior and seasoned power supply engineer from the others --- the ability to navigate and surmount a veritable minefield of tricky issues that can only be learned the hard way, by actual hands-on experience on the job. This book presents practical knowledge the author acquired rather painfully, while working "e;in the trenches"e; for several years in major engineering companies scattered across several continents. This is intended to be the mythical senior engineer's "e;bag of tricks,"e; finally made available in the form of an easy-to-read book on your shelf. This book will make life for the ambitious power supply engineer much simpler --- besides reducing significantly, the rigorous requirement of having to be a senior engineer's protege for years on end, just to gain a small measure of real success in this field.* A practical presentation that answers the important question: why is my switching converter behaving so differently than what I was expecting on the basis of my paper design? And how do I bridge that huge gap?* For the first time, a systematic and thorough discussion of troubleshooting switching power supplies.* Coverage of AC/DC and DC/DC power supplies. * Bench Evaluation of semiconductor ICs used in power conversion --- describing standard and unusual techniques mastered by the author, while testing similar chips at National Semiconductor. * Detailed coverage of vital topics that haven't been covered by available sources --- grounding systems, the subtleties of component datasheets, and using instruments and probes effectively.* Systematic investigation (type of failure mechanism, topology, etc.) and solutions for 5 years of reported power supply issues on a prominent, public web forum. This approach will ensure that engineers will not repeat the same mistakes. * A unique, readable style: personal and direct; no mystification--- just the plain truth, easily and logically explained, with plenty of pictures, graphs and plots.

Inhalt

Front cover 1
Troubleshooting Switching Power Converters: A Hands-on Guide 4
Copyright page 5
Table of contents 6
Preface 10
Acknowledgments 14
CHAPTER 1: Thinking Power 16
Practice and Theory: Two Sides of the Same Coin 16
Leave Your Past Perceptions Behind 17
Choose Your Friends Carefully 19
Finding Solutions that Converge 24
The Ripple Effect in Power Supplies 25
Experience Does Count No Ifs, Ands, or Buts about That
Never Ignore a Problem Until It Is Too Late 28
Know Your Instruments Well 29
Heatseekers: On the Road with Symptomatic Troubleshooting 29
Causality Can Be the First Casualty 34
Learn from (Their) Mistakes 40
The Problem with Problem Solving 41
CHAPTER 2: High-Frequency Effects and the Importance of Input Decoupling 48
Lies, Damn Lies, and Schematics 48
Occupational Hazards 57
Watch the Feedback Trace Closely 59
Physical Distances Become Critical 60
Estimating Harmonic Amplitudes 62
High-Frequency Input Decoupling 63
Don’t Forget to Place that 0.1mF Ceramic Capacitor Really Close to the IC 64
You Need Bulk Capacitance, Too 65
Where Is the “Missing” Current Coming From? 66
Check Your Bench Power Supply 70
Lack of Bulk Capacitance and/or Too Much ESR Can Play Havoc 71
Single Ceramic Capacitor for Both Noise and Ripple? 73
The Control Also Needs a Clean Supply Rail 75
Boost Topology Decoupling Is Slightly Different 75
CHAPTER 3: Output Noise and Filtering 78
Measuring Output Noise and Ripple 78
CHAPTER 4: Using Capacitors Wisely 94
Introduction 94
Part 1: Aluminum Electrolytics 94
Part 2: Ceramic Capacitors 108
CHAPTER 5: Maximizing the Effectiveness of the Ground Plane 124
How to Parallel Output Capacitors for Proper Sharing 124
Integrated Switcher IC Solutions Versus Controller IC Solutions 129
Quick Check on Current through Aluminum Capacitors 129
Secondary Side Trace Inductances and Their Impact on Efficiency 130
Current Return Paths in the Ground Plane 132
Paralleling Traces to Reduce Inductance 135
CHAPTER 6: Printed Circuit Board Layout for AC-DC and DC-DC Converters 140
Introduction 140
Evaluation Boards (EVBs) 140
CHAPTER 7: Working without a Ground Plane 164
384x-based Controllers on Single-sided Boards 164
Watch the Primary Side Current Loop 166
And the Secondary Side Current Loop, Too 167
The Real “Switch” 172
CHAPTER 8: Home-Grown Strategies in Troubleshooting 176
Peeling the Onion 176
CHAPTER 9: Effective Bench Work 204
Introduction 204
Basic Equipment 204
CHAPTER 10: Efficiency Rules 222
Ensure the Drive Is Adequate 222
Minimize Capacitive Parasitics 225
Proper Design of Snubbers and Clamps 227
Varying the Frequency 231
The Time-sharing Principle 231
Understanding the Shape of Buck Efficiency Curves 233
Estimating the Ratio of Conduction Loss to Switching Loss 236
CHAPTER 11: Magnetics, EMI, and Noise 244
The Wish List 244
Twisting and Turning Your Way Out of EMI Problems 248
Location of Clamp Affects Noise, Too 253
A Cheat-sheet for EMI Troubleshooting 254
CHAPTER 12: Discussion Forums, Datasheets, and Other Real-World Issues 262
Thinking Is the Key 262
Cross-check Everything 262
Product Liability Concerns 264
It’s All about the Customer 265
The Q& A Session
Appendix 306
Index 308

Produkt-Details

• Erscheint lt. Verlag: 8.4.2011
• Sprache: englisch
• Themenwelt: Technik ► Elektrotechnik / Energietechnik
• ISBN-10: 0-08-055125-4 / 0080551254
• ISBN-13: 978-0-08-055125-8 / 9780080551258