Contents
Preface ...............................................................................................................................ix
About the Editor ................................................................................................................ xi
About the Contributors ...................................................................................................xiii
Chapter 1: An Introduction to the Linear Regulator ........................................................1
1.1 Basic Linear Regulator Operation ..............................................................................2
1.2 General Linear Regulator Considerations ...................................................................3
1.3 Linear Power Supply Design Examples ......................................................................6
Chapter 2: Basic Switching Circuits ................................................................................13
2.1 Energy Storage Basics ..............................................................................................14
2.2 Buck Converter .........................................................................................................15
2.3 Boost Converter ........................................................................................................17
2.4 Inverting Boost Converter .........................................................................................19
2.5 Buck-Boost Converter ...............................................................................................19
2.6 Transformer Isolated Converters ...............................................................................20
2.7 Synchronous Rectifi cation ........................................................................................23
2.8 Charge Pumps ...........................................................................................................25
Chapter 3: DC-DC Converter Design and Magnetics .....................................................29
3.1 DC Transfer Functions ..............................................................................................31
3.2 The DC Level and the Swing of the Inductor Current Waveform .........................32
3.3 Defining the AC, DC, and Peak Currents ..................................................................35
3.4 Understanding the AC, DC and Peak Currents .........................................................37
3.5 Defining the “ Worst-case ” Input Voltage ..................................................................39
3.6 The Current Ripple Ratio r .......................................................................................42
3.7 Relating r to the Inductance ......................................................................................43
3.8 The Optimum Value of r ...........................................................................................44
3.9 Do We Mean Inductor? or Inductance? ....................................................................45
3.10 How Inductance and Inductor Size Depend on Frequency .......................................46
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3.11 How Inductance and Inductor Size Depend on Load Current ..................................47
3.12 How Vendors Specify the Current Rating of an Off-the-shelf
Inductor and How to Select it ...................................................................................47
3.13 What is the Inductor Current Rating We Need to Consider for a
Given Application? ....................................................................................................49
3.14 The Spread and Tolerance of the Current Limit ........................................................52
3.15 Worked Example (1) .................................................................................................55
3.16 Worked Examples (2, 3, and 4) .................................................................................67
3.17 Worked Example (5)—When Not to Increase the Number of Turns ........................72
3.18 Worked Example (6)—Characterizing an Off-the-shelf Inductor in a
Specific Application ..................................................................................................77
3.19 Calculating the “ Other ” Worst-case Stresses ............................................................84
Chapter 4: Control Circuits ..............................................................................................93
4.1 Basic Control Circuits ...............................................................................................94
4.2 The Error Amplifi er ...................................................................................................97
4.3 Error Amplifi er Compensation ..................................................................................98
4.4 A Representative Voltage Mode PWM Controller ..................................................102
4.5 Current Mode Control .............................................................................................107
4.6 A Representative Current Mode PWM Controller ..................................................109
4.7 Charge Pump Circuits .............................................................................................113
4.8 Multiple Phase PWM Controllers ...........................................................................116
4.9 Resonant Mode Controllers ....................................................................................116
Chapter 5: Non-isolated Circuits ....................................................................................117
5.1 General Design Method ..........................................................................................118
5.2 Buck Converter Designs .........................................................................................118
5.3 Boost Converter Designs .........................................................................................127
5.4 Inverting Designs ....................................................................................................133
5.5 Step Up/Step Down (Buck/Boost) Designs ............................................................137
5.6 Charge Pump Designs .............................................................................................141
5.7 Layout Considerations ............................................................................................145
Chapter 6: Transformer-isolated Circuits ......................................................................149
6.1 Feedback Mechanisms ............................................................................................150
6.2 Flyback Circuits ......................................................................................................157
6.3 Practical Flyback Circuit Design ............................................................................163
6.4 Off-Line Flyback Example .....................................................................................163
6.5 Non-isolated Flyback Example ...............................................................................170
6.6 Forward Converter Circuits .....................................................................................174
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6.7 Practical Forward Converter Design .......................................................................175
6.8 Off-Line Forward Converter Example ....................................................................176
6.9 Non-isolated Forward Converter Example .............................................................180
6.10 Push-Pull Circuits ...................................................................................................184
6.11 Practical Push-Pull Circuit Design ..........................................................................185
6.12 Half Bridge Circuits ................................................................................................189
6.13 Practical Half Bridge Circuit Design ......................................................................191
6.14 Full Bridge Circuits .................................................................................................194
Chapter 7: Power Semiconductors .................................................................................197
7.1 Introduction .............................................................................................................197
7.2 Power Diodes and Thyristors ..................................................................................198
7.3 Gate Turn-Off Thyristors ........................................................................................215
7.4 Bipolar Power Transistors .......................................................................................217
7.5 Power MOSFETs ....................................................................................................226
7.6 Insulated Gate Bipolar Transistor (IGBT) ..............................................................237
7.7 MOS Controlled Thyristor (MCT) ..........................................................................239
References ......................................................................................................................241
Bibliography ..................................................................................................................243
Chapter 8: Conduction and Switching Losses ...............................................................247
8.1 Switching a Resistive Load .....................................................................................248
8.2 Switching an Inductive Load ..................................................................................253
8.3 Switching Losses and Conduction Loss .................................................................256
8.4 A Simplified Model of the MOSFET for Studying Inductive
Switching Losses .....................................................................................................257
8.5 The Parasitic Capacitances Expressed in an Alternate System ...............................259
8.6 Gate Threshold Voltage ...........................................................................................261
8.7 The Turn-on Transition ...........................................................................................261
8.8 The Turn-off Transition ...........................................................................................264
8.9 Gate Charge Factors ................................................................................................266
8.10 Worked Example .....................................................................................................269
8.11 Applying the Switching Loss Analysis to Switching Topologies ...........................273
8.12 Worst-case Input Voltage for Switching Losses ......................................................274
8.13 How Switching Losses Vary with the Parasitic Capacitances .................................275
8.14 Optimizing Driver Capability vis-à-vis MOSFET Characteristics .........................277
Chapter 9: Power Factor Correction ..............................................................................279
9.1 How Power Factor and Harmonics are Specifi ed ...................................................284
9.2 A Universal Input, 180W, Active Power Factor Correction Circuit ........................286
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Chapter 10: Off-line Converter Design and Magnetics .................................................295
10.1 Flyback Converter Magnetics .................................................................................296
10.2 Forward Converter Magnetics .................................................................................319
Chapter 11: A “ True Sine Wave ” Inverter Design Example .........................................345
11.1 Design Requirements ..............................................................................................346
11.2 Design Description ..................................................................................................346
11.3 Preregulator Detailed Design ..................................................................................352
11.4 Output Converter Detailed Design ..........................................................................356
11.5 H Bridge Detailed Design .......................................................................................358
11.6 Bridge Drive Detailed Design .................................................................................361
Chapter 12: Thermal Analysis and Design ....................................................................365
12.1 Developing the Thermal Model ..............................................................................366
12.2 Power Packages on a Heatsink (to-3, to-220, to-218, etc.) .....................................368
12.3 Power Packages Not on a Heatsink (Free Standing) ...............................................369
12.4 Radial-leaded Diodes ..............................................................................................370
12.5 Surface Mount Parts ................................................................................................371
12.6 Examples of Some Thermal Applications ...............................................................372
Index ................................................................................................................................377
Contents

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