Switchmode Power Supply Handbook, Third Edition

Contents......Page 5
Preface......Page 16
Acknowledgments......Page 18
Units, Symbols, Dimensions, and Abbreviations Used in This Book......Page 19
List of Figures and Tables......Page 27
Part 1 Functions and Requirements Commonto Most Direct-Off-Line Switchmode Power Supplies......Page 34
1.2 Input Transient Voltage Protection......Page 36
1.5 Common-Mode Noise......Page 37
1.8 Line Rectification and Capacitor Input Filters......Page 38
1.11 Soft Start......Page 39
1.14 Output Undervoltage Protection......Page 40
1.18 Proportional Drive Circuits......Page 41
1.22 Output Filtering, Common-Mode Noise, and Input-to-Output Isolation......Page 42
1.24 Power Good Signals......Page 43
1.27 Synchronization......Page 44
1.29 Forced Current Sharing......Page 45
1.30 Remote Sensing......Page 46
1.34 Input Safety Requirements......Page 47
2.2 Location Categories......Page 50
2.3 Likely Rate of Surge Occurrences......Page 52
2.4 Surge Voltage Waveforms......Page 54
2.6 Metal Oxide Varistors (Movs, Voltage-Dependent Resistors)......Page 55
2.7 Transient Protection Diodes......Page 56
2.8 Gas-Filled Surge Arresters......Page 57
2.9 Line Filter, Transient Suppressor Combinations......Page 58
2.10 Category A Transient Suppression Filters......Page 59
2.11 Category B Transient Suppression Filters......Page 60
2.13 The Cause of “Ground Return Voltage Bump” Stress......Page 61
2.14 Problems......Page 62
3.1 Introduction......Page 64
3.4 Safety Regulations (Ground Return Currents)......Page 66
3.6 Suppressing EMI at Source......Page 68
3.7 Example......Page 70
3.8 Line Impedance Stabilization Network (LISN)......Page 71
3.9 Line Filter Design......Page 72
3.10 Common-Mode Line Filter Inductors......Page 73
3.13 Problems......Page 74
4.2 Faraday Screens as Applied to Switching Devices......Page 76
4.3 Transformer Faraday Screens and Safety Screens......Page 77
4.4 Faraday Screens on Output Components......Page 78
4.5 Reducing Radiated EMI in Gapped Transformer Cores......Page 79
4.6 Problems......Page 81
5.2 Fuse Parameters......Page 82
5.3 Types of Fuses......Page 84
5.6 Transformer Input Fuses......Page 85
5.7 Problems......Page 86
6.1 Introduction......Page 88
6.3 Effective Series Resistance R[sub(s)]......Page 89
6.4 Constant-Power Load......Page 90
6.7 Input Current, Capacitor Ripple, and Peak Currents......Page 92
6.9 Selecting Inrush-Limiting Resistance......Page 94
6.11 Design Example......Page 95
6.12 DC Output Voltage and Regulation for Rectifier Capacitor Input Filters......Page 96
6.14 Selecting Reservoir and/or Filter Capacitor Size......Page 99
6.16 Power Factor and Efficiency Measurements......Page 103
6.17 Problems......Page 104
7.2 Series Resistors......Page 106
7.4 Active Limiting Circuits (Triac Start Circuit)......Page 107
7.5 Problems......Page 108
8.2 Dissipative (Passive) Start Circuit......Page 110
8.3 Transistor (Active) Start Circuit......Page 111
8.4 Impulse Start Circuits......Page 112
9.1 Introduction......Page 114
9.2 Soft-Start Circuit......Page 115
9.4 Problems......Page 116
10.2 Typical Causes of Turn-On Voltage Overshoot in Switchmode Supplies......Page 118
10.3 Overshoot Prevention......Page 119
10.4 Problems......Page 121
11.3 Type 1, SCR “Crowbar” Overvoltage Protection......Page 122
11.4 “Crowbar” Performance......Page 125
11.5 Limitations of “Simple” Crowbar Circuits......Page 126
11.6 Type 2, Overvoltage Clamping Techniques......Page 127
11.7 Overvoltage Clamping with SCR “Crowbar” Backup......Page 128
11.8 Selecting Fuses for SCR “Crowbar” Overvoltage Protection Circuits......Page 130
11.9 Type 3, Overvoltage Protection by Voltage Limiting Techniques......Page 131
11.10 Problems......Page 132
12.2 Undervoltage Suppressor Performance Parameters......Page 134
12.3 Basic Principles......Page 136
12.5 Operating Principles (Practical Circuit)......Page 138
12.7 Problems......Page 139
13.3 Type 1, Overpower Limiting......Page 140
13.5 Type 1, Form B, Delayed Overpower Shutdown Protection......Page 141
13.7 Type 1, Form D, Constant Power Limiting......Page 142
13.9 Type 2, Output Constant Current Limiting......Page 143
13.10 Type 3, Overload Protection by Fuses, Current Limiting, or Trip Devices......Page 144
13.11 Problems......Page 145
14.2 Foldback Principle......Page 146
14.3 Foldback Circuit Principles as Applied to a Linear Supply......Page 147
14.4 “Lockout” in Foldback Current-Limited Supplies......Page 149
14.5 Reentrant Lockout with Cross-Connected Loads......Page 151
14.7 Problems......Page 153
15.2 Secondary Breakdown......Page 154
15.5 Correct Turn-On Waveform......Page 155
15.7 Optimum Drive Circuit for High-Voltage Transistors......Page 156
15.8 Problems......Page 158
16.2 Example of a Proportional Drive Circuit......Page 160
16.4 Turn-Off Action......Page 161
16.6 Wide-Range Proportional Drive Circuits......Page 162
16.8 Turn-On Action......Page 163
16.10 Problems......Page 164
17.2 Baker Clamp......Page 166
17.3 Problems......Page 167
18.2 Snubber Circuit (with Load Line Shaping)......Page 168
18.4 Establishing Snubber Component Values by Empirical Methods......Page 170
18.6 Turn-Off Dissipation in Transistor Q1......Page 172
18.9 Miller Current Effects......Page 173
18.10 The Weaving Low-Loss Snubber Diode......Page 174
18.11 “Ideal” Drive Circuits for High-Voltage Bipolar Transistors......Page 175
18.12 Problems......Page 177
19.1 Introduction......Page 178
19.3 Cross-Coupled Inhibit......Page 180
19.5 Problems......Page 181
20.2 Basic Requirements......Page 182
20.4 Two-Stage Filters......Page 184
20.5 High-Frequency Choke Example......Page 185
20.7 Resonant Filter Example......Page 187
20.8 Common-Mode Noise Filters......Page 188
20.9 Selecting Component Values for Output Filters......Page 189
20.11 Design Example......Page 190
20.12 Output Capacitor Value......Page 191
20.13 Problems......Page 193
21.3 Simple Power Failure Warning Circuits......Page 194
21.4 Dynamic Power Failure Warning Circuits......Page 195
21.5 Independent Power Failure Warning Module......Page 198
21.6 Power Failure Warning in Flyback Converters......Page 199
21.7 Fast Power Failure Warning Circuits......Page 200
21.8 Problems......Page 202
22.2 Example......Page 204
22.3 Saturable Reactor Voltage Adjustment......Page 205
22.4 Reactor Design......Page 206
22.5 Problems......Page 207
23.2 60-Hz Line Transformers......Page 208
23.4 Operating Principles......Page 209
23.5 Stabilized Auxiliary Converters......Page 210
23.6 High-Efficiency Auxiliary Supplies......Page 211
23.9 Low Noise Distributed Auxiliary Converters......Page 212
23.10 Block Diagram of a Distributed Auxiliary Power System......Page 213
23.11 Block 1, Rectifier and Linear Regulator......Page 214
23.12 Block 2, Sine Wave Inverter......Page 217
23.13 Output Modules......Page 221
23.14 Sine Wave Inverter Transformer Design......Page 223
23.15 Reducing Common Mode Noise......Page 226
24.2 Master-Slave Operation......Page 228
24.3 Voltage-Controlled Current Sources......Page 229
24.4 Forced Current Sharing......Page 230
24.5 Parallel Redundant Operation......Page 232
24.6 Problems......Page 233
Part 2 Design: Theory and Practice......Page 234
1.2 Expected Performance......Page 236
1.3 Operating Modes......Page 238
1.5 Energy Storage Phase......Page 239
1.6 Energy Transfer Modes (Flyback Phase)......Page 240
1.7 Factors Defining Operating Modes......Page 242
1.8 Transfer Function Anomaly......Page 243
1.9 Transformer Throughput Capability......Page 244
1.11 Specification Example for a 110-W Direct-Off-Line Flyback Power Supply......Page 246
1.12 Problems......Page 247
2.2 Core Parameters and the Effect of an Air Gap......Page 250
2.3 General Design Considerations......Page 253
2.4 Design Example for a 110-W Flyback Transformer......Page 254
2.7 Problems......Page 264
3.2 Self-Tracking Voltage Clamp......Page 266
3.3 Flyback Converter “Snubber” Networks......Page 268
3.4 Problems......Page 270
4.2 Primary Components......Page 272
4.3 Secondary Power Components......Page 273
4.4 Output Capacitors......Page 274
4.5 Capacitor Life......Page 276
4.6 General Conclusions Concerning Flyback Converter Components......Page 277
4.7 Problems......Page 278
5.2 Operating Principle......Page 280
5.3 Useful Properties......Page 282
5.5 Drive Circuitry......Page 283
5.8 Problems......Page 284
6.2 Classes of Operation......Page 286
6.3 General Operating Principles......Page 287
6.5 Control Circuit (Brief Description)......Page 290
6.6 Squegging......Page 292
6.8 Problems......Page 293
7.2 Power Limiting and Current-Mode Control as Applied to the Self-Oscillating Flyback Converter......Page 294
7.3 Voltage Control Loop......Page 295
7.5 Using Field-Effect Transistors in Variable-Frequency Flyback Converters......Page 297
7.6 Problems......Page 298
8.2 Operating Principles......Page 300
8.3 Limiting Factors for the Value of the Output Choke......Page 302
8.5 Energy Recovery Winding (P2)......Page 303
8.6 Advantages......Page 304
8.8 Problems......Page 305
9.1 Introduction......Page 306
9.2 Transformer Design Example......Page 307
9.3 Selecting Power Transistors......Page 313
9.6 Conclusions......Page 314
10.2 Operating Principles......Page 316
11.1 General Considerations......Page 320
11.2 Design Notes......Page 324
12.2 Operating Principles......Page 326
12.4 Problem Areas......Page 328
12.5 Current-Mode Control and Subharmonic Ripple......Page 329
12.8 Soft Start......Page 330
12.10 Optimum Flux Density......Page 331
12.12 Calculating Primary Turns......Page 333
12.14 Calculate Secondary Turns......Page 334
12.15 Control and Drive Circuits......Page 335
12.17 Problems......Page 336
13.2 Operating Principles......Page 338
13.4 Transformer Design Example......Page 342
13.6 Transient Saturation Effects......Page 348
13.8 Problems......Page 349
14.3 Operating Principle, Single-Transformer Converters......Page 350
14.4 Transformer Design......Page 352
15.2 Operating Principles (Gain-Limited Switching)......Page 356
15.3 Defining the Switching Current......Page 358
15.4 Choosing Core Materials......Page 359
15.5 Transformer Design (Saturating-Core-Type Converters)......Page 361
15.6 Problems......Page 366
16.2 Operating Principles......Page 368
16.3 Saturated Drive Transformer Design......Page 370
16.5 Main Power Transformer Design......Page 371
16.6 Problems......Page 372
17.2 Basic Principles of the DC-to-DC Transformer Concept......Page 374
17.3 DC-to-DC Transformer Example......Page 375
17.4 Problems......Page 377
18.2 Buck Regulator, Cascaded with a DC-to-DC Transformer......Page 378
18.3 Operating Principles......Page 379
18.4 Buck Regulator Section......Page 380
18.7 Compound Regulators with Secondary Post Regulators......Page 381
18.8 Problems......Page 383
19.2 Operating Principles......Page 384
19.5 Flux Density Balancing......Page 388
19.7 Flux Doubling......Page 389
19.8 Push-Pull Transformer Design Example......Page 390
19.9 Problems......Page 395
20.1 Introduction......Page 396
20.2 Operating Principles......Page 399
20.4 Inductor Design for Switching Regulators......Page 406
20.5 Inductor Design Example......Page 407
20.7 The Ripple Regulator......Page 408
20.8 Problems......Page 409
21.2 Operating Principles......Page 410
21.3 The Saturable Reactor Power Regulator Principle......Page 412
21.4 The Saturable Reactor Power Regulator Application......Page 413
21.5 Saturable Reactor Quality Factors......Page 415
21.6 Selecting Suitable Core Materials......Page 416
21.7 Controlling the Saturable Reactor......Page 417
21.8 Current Limiting the Saturable Reactor Regulator......Page 419
21.9 Push-Pull Saturable Reactor Secondary Power Control Circuit......Page 420
21.11 Some Limiting Factors in Saturable Reactor Regulators......Page 421
21.12 The Case for Constant-Voltage or Constant-Current Reset (High-Frequency Instability Considerations)......Page 422
21.14 Design Example......Page 423
21.15 Problems......Page 425
22.2 Constant-Voltage Supplies......Page 426
22.4 Compliance Voltage......Page 427
22.5 Problems......Page 429
23.1 Introduction......Page 430
23.2 Basic Operation (Power Section)......Page 431
23.3 Drive Circuit......Page 432
23.4 Maximum Transistor Dissipation......Page 433
23.6 Voltage Control and Current Limit Circuit......Page 434
23.7 Control Circuit......Page 436
23.8 Problems......Page 438
24.1 Introduction......Page 440
24.3 Special Properties of Flyback Converters......Page 441
24.4 Operating Principles......Page 442
24.5 Practical Limiting Factors......Page 443
24.7 Initial Conditions......Page 444
24.9 Block Schematic Diagram (General Description)......Page 445
24.10 Overall System Operating Principles......Page 447
24.11 Individual Block Functions......Page 448
24.12 Primary Power Limiting......Page 452
24.13 Conclusions......Page 454
25.1 Design Steps......Page 456
25.3 Problems......Page 461
Part 3 Applied Design......Page 462
1.1 Introduction......Page 464
1.3 Common-Mode Line-Filter Inductors......Page 465
1.4 Design Example of a Common-Mode Line-Filter Inductor (Using a Ferrite E Core and Graphical Design Method)......Page 470
1.6 Series-Mode Line-Input-Filter Inductors......Page 471
1.7 Chokes (Inductors with DC Bias)......Page 472
1.8 Design Example of a Gapped Ferrite E-Core Choke (Using an Empirical Method)......Page 475
1.9 Design Example of Chokes for Buck and Boost Converters (by Area Product Graphical Methods and by Calculation)......Page 476
1.10 Choke Design Example for a Buck Regulator (Using a Ferrite E Core and Graphical AP Design Method)......Page 479
1.11 Ferrite and Iron Powder Rod Chokes......Page 486
1.12 Problems......Page 488
2.1 Introduction......Page 490
2.3 Core Permeability......Page 491
2.5 Methods Used to Design Iron Powder E-Core Chokes (Graphical Area Product Method)......Page 492
2.6 Example of Iron Powder E-Core Choke Design (Using the Graphical Area Product Method)......Page 495
3.1 Introduction......Page 502
3.3 Swinging Chokes......Page 503
3.5 Design Example (Option A)......Page 506
3.6 Design Example (Option B)......Page 508
3.7 Design Example (Option C)......Page 510
3.9 Total Dissipation and Temperature Rise......Page 511
3.10 Linear (Toroidal) Choke Design......Page 512
Appendix 3.A, Derivation of Area Product Equations......Page 514
Appendix 3.B, Derivation of Packing and Resistance Factors......Page 520
Appendix 3.C, Derivation of Nomogram 3.3.1......Page 523
4.2 Transformer Size (General Considerations)......Page 524
4.3 Optimum Efficiency......Page 525
4.4 Optimum Core Size and Flux Density Swing......Page 526
4.5 Calculating Core Size in Terms of Area Product......Page 529
4.9 The Effect of Frequency on Transformer Size......Page 530
4.10 Flux Density Swing Δb......Page 531
4.12 Calculation of Primary Turns......Page 533
4.14 Half Turns......Page 535
4.16 Skin Effects and Optimum Wire Thickness......Page 536
4.17 Winding Topology......Page 539
4.18 Temperature Rise......Page 543
4.21 Eliminating Breakdown Stress in Bifilar Windings......Page 546
4.22 RFI Screens and Safety Screens......Page 547
4.23 Transformer Half-Turn Techniques......Page 548
4.24 Transformer Finishing and Vacuum Impregnation......Page 550
4.25 Problems......Page 551
Appendix 4.A, Derivation of Area Product Equations for Transformer Design......Page 552
Appendix 4.B, Skin and Proximity Effects in High-Frequency Transformer Windings......Page 556
5.2 Core Size and Optimum Flux Density Swing......Page 566
5.4 Calculate Primary Turns......Page 567
5.7 Secondary Turns......Page 568
5.11 Design Confirmation......Page 569
5.13 Secondary Copper Loss......Page 570
5.16 Efficiency......Page 571
6.1 Introduction......Page 572
6.3 Forced Flux Balancing in Duty-Ratio-Controlled Push-Pull Converters......Page 573
6.5 Problems......Page 576
7. Flux Doubling......Page 578
8.2 Some Causes of Instability in Switchmode Supplies......Page 580
8.3 Methods of Stabilizing the Loop......Page 581
8.4 Stability Testing Methods......Page 582
8.6 Transient Testing Analysis......Page 583
8.8 Measurement Procedures for Bode Plots of Closed-Loop Power Supply Systems......Page 585
8.10 Test Techniques......Page 587
8.11 Measurement Procedures for Bode Plots of Open-Loop Power Supply Systems......Page 588
8.12 Establishing Optimum Compensation Characteristic by the “Difference Method”......Page 589
8.13 Some Causes of Stubborn Instability......Page 590
8.14 Problems......Page 592
9.2 Explanation of the Dynamics of the Right-Half-Plane Zero......Page 594
9.3 The Right-Half-Plane Zero—A Simplified Explanation......Page 595
9.4 Problems......Page 599
10.2 The Principles of Current-Mode Control......Page 600
10.4 Performance of the Complete Energy Transfer Current-Modecontrolled Flyback Converter......Page 603
10.5 The Advantages of Current-Mode Control in Continuous-Inductor-Current Converter Topologies......Page 604
10.7 Advantages of Current-Mode Control in Continuous-Inductor-Current-Mode Buck Regulators......Page 607
10.8 Disadvantages Intrinsic to Current-Mode Control......Page 610
10.10 Asymmetry Caused by Charge Imbalance in Current-Mode-Controlled Half-Bridge Converters and Other Topologies Using DC Blocking Capacitors......Page 613
10.11 Summary......Page 614
10.12 Problems......Page 616
11.2 Optocoupler Interface Circuit......Page 618
11.3 Stability and Noise Sensitivity......Page 621
11.4 Problems......Page 622
12.1 Introduction......Page 624
12.2 Establishing Capacitor RMS Ripple Current Ratings From Published Data......Page 626
12.4 Recommended Test Procedures......Page 627
12.5 Problems......Page 628
13.3 Resistance/Inductance Ratio of a Simple Shunt......Page 630
13.4 Measurement Error......Page 631
13.6 Problems......Page 632
14.2 Types of Current Transformers......Page 634
14.3 Core Size and Magnetizing Current (All Types)......Page 635
14.4 Current Transformer Design Procedure......Page 637
14.5 Unidirectional Current Transformer Design Example......Page 638
14.6 Type 2, Current Transformers (for Alternating Current) Push-Pull Applications)......Page 641
14.7 Type 3, Flyback-Type Current Transformers......Page 642
14.8 Type 4, DC Current Transformers (Dcct)......Page 644
14.9 Using Current Transformers in Flyback Converters......Page 649
15.1 Introduction......Page 650
15.3 The Design of Current Probes for Unidirectional (Discontinuous) Current Pulse Measurements......Page 651
15.4 Select Core Size......Page 653
15.6 Check Magnetization Current Error......Page 654
15.7 Current Probes in Applications with DC and AC Currents......Page 655
15.8 High-Frequency AC Current Probes......Page 656
15.10 Problems......Page 657
16.2 The Effect of High Temperatures on Semiconductor Life and Power Supply Failure Rates......Page 658
16.3 The Infinite Heat Sink, Heat Exchangers, Thermal Shunts, and Their Electrical Analogues......Page 660
16.4 The Thermal Circuit and Equivalent Electrical Analogue......Page 661
16.5 Heat Capacity C[sub(h)] (Analogous to Capacitance C)......Page 664
16.6 Calculating Junction Temperature......Page 665
16.7 Calculating the Heat Sink Size......Page 666
16.8 Methods of Optimizing Thermal Conductivity Paths, and Where to Use “Thermal Conductive Joint Compound”......Page 668
16.9 Convection, Radiation, or Conduction?......Page 671
16.10 Heat Exchanger Efficiency......Page 674
16.11 The Effect of Input Power on Thermal Resistance......Page 675
16.12 Thermal Resistance and Heat Exchanger Area......Page 676
16.13 Forced-Air Cooling......Page 677
16.14 Problems......Page 678
Part 4 Supplementary......Page 680
1.1 Introduction......Page 682
1.2 Power Factor Correction Basics, Myths, and Facts......Page 683
1.3 Passive Power Factor Correction......Page 688
1.4 Active Power Factor Correction......Page 692
1.5 More Regulator Topologies......Page 698
1.6 Buck Regulators......Page 703
1.7 Combinations of Converters......Page 705
1.8 Integrated Circuits for Power Factor Control......Page 708
1.9 Typical IC Control System......Page 711
1.10 Applied Design......Page 717
1.11 Choice of Control IC......Page 721
1.12 Power Factor Control Section......Page 728
1.13 Buck Section Drive Stage......Page 731
1.14 Power Components......Page 734
Appendix 1.A, Boost Choke for Power Factor Correction: Design Example......Page 741
2.1 Introduction......Page 748
2.2 Advantages and Limitations of Hard Switching Methods......Page 749
2.3 Fully Resonant Switching Systems......Page 751
2.4 Current Fed Parallel Resonant Ballast......Page 754
2.5 Wound Component Design......Page 760
2.6 Conclusions......Page 764
3.2 Hard Switching Methods......Page 766
3.5 The Power Section of a Full-Bridge, Quasi-Resonant, Zero-Voltage Transition, Phase-Shift Modulated, 10-kW Converter......Page 767
3.6 Q1-Q4 Bridge FET Drive Timing......Page 770
3.7 Power Switching Sequence......Page 771
3.8 Optimum Conditions for Zero Voltage Switching......Page 781
3.9 Establishing the Optimum Resonant Inductance (L[sub(1e)])......Page 786
3.11 Output Rectifier Snubbing......Page 787
3.12 Switching Speed and Transition Periods......Page 788
3.13 Primary and Secondary Power Circuits......Page 791
3.14 Power Waveforms and Power Transfer Conditions......Page 792
3.15 Basic FET Drive Principles......Page 793
3.16 Modulation and Control Circuits......Page 796
3.18 Control ICs......Page 800
4.1 Introduction......Page 802
4.2 Basic FET Resonant Inverter......Page 803
4.3 Starting the FET Inverter......Page 805
4.4 Improved Gate Drive......Page 807
4.5 Other Methods of Starting......Page 809
4.7 Summary......Page 810
5.2 Frequency and Amplitude Control Theory......Page 812
5.3 Operating Theory for the Wide Range Sine Wave VCO......Page 814
5.4 Circuit Performance......Page 816
B......Page 818
C......Page 819
E......Page 820
L......Page 821
P......Page 822
S......Page 823
V......Page 824
References......Page 825
A......Page 828
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