Switch-Mode Power Supplies : Spice Simulations and Practical Designs

by Basso, Christophe

• ISBN13: 9780071508582
• ISBN10: 0071508589
• Edition: 1st
• Format: Package
• Copyright: 2008-02-04
• Publisher: McGraw-Hill Professional

Summary

Learn about the latest SPICe solutions This is a collection of SPICE solutions to the most difficult problem facing power supply designers: creating smaller and more heat-efficient power supplies in shorter design cycles. This invaluable resource provides practical models and easily customizable solutions.

Author Biography

Chrisophe Basso is a technical engineer at ONSemdiconductor (formerly Motorola Semiconductor) and a frequentcontributor to EDN Magazine.

Table of Contents

Foreword	p. xiii
Preface	p. xv
Nomenclature	p. xvii
Introduction to Power Conversion	p. 1
"Do You Really Need to Simulate?"	p. 1
What You Will Find in the Following Pages	p. 2
What You Will Not Find in This Book	p. 3
Converting Power with Resistors	p. 3
Associating Resistors	p. 3
A Closed-Loop System	p. 5
Deriving Useful Equations with the Linear Regulator	p. 7
A Practical Working Example	p. 10
Building a Simple Generic Linear Regulator	p. 14
Conclusion on Linear Regulators	p. 17
Converting Power with Switches	p. 18
A Filter Is Needed	p. 19
Current in the Inductance, Continuous or Discontinuous?	p. 21
Charge and Flux Balance	p. 25
Energy Storage	p. 27
The Duty Cycle Factory	p. 27
Voltage-Mode Operation	p. 27
Current-Mode Operation	p. 29
The Buck Converter	p. 30
On-Time Event	p. 30
Off-Time Event	p. 31
Buck Waveforms-CCM	p. 31
Buck Waveforms-DCM	p. 34
Buck Transition Point DCM-CCM	p. 37
Buck CCM Output Ripple Voltage Calculation	p. 39
Now with the ESR	p. 41
Buck Ripple, the Numerical Application	p. 41
The Boost Converter	p. 42
On-Time Event	p. 43
Off-Time Event	p. 44
Boost Waveforms-CCM	p. 44
Boost Waveforms-DCM	p. 47
Boost Transition Point DCM-CCM	p. 50
Boost CCM Output Ripple Voltage Calculations	p. 51
Now with the ESR	p. 54
Boost Ripple, the Numerical Application	p. 54
The Buck-Boost Converter	p. 55
On-Time Event	p. 56
Off-Time Event	p. 56
Buck-Boost Waveforms-CCM	p. 57
Buck-Boost Waveforms-DCM	p. 59
Buck-Boost Transition Point DCM-CCM	p. 63
Buck-Boost CCM Output Ripple Voltage Calculation	p. 64
Now with the ESR	p. 65
Buck-Boost Ripple, the Numerical Application	p. 65
Input Filtering	p. 66
The RLC Filter	p. 67
A More Comprehensive Representation	p. 70
Creating a Simple Closed-Loop Current Source with SPICE	p. 71
Understanding Overlapping Impedances	p. 72
Damping the Filter	p. 76
Calculating the Required Attenuation	p. 79
Fundamental Frequency Evaluation	p. 80
Selecting the Right Cutoff Frequency	p. 82
What I Should Retain from Chap. 1	p. 85
References	p. 85
A RLC Transfer Function	p. 86
The Capacitor Equivalent Model	p. 89
Power Supply Classification by Topologies	p. 93
Small-Signal Modeling	p. 95
State-Space Averaging	p. 98
SSA at Work for the Buck Converter-First Step	p. 100
The DC Transformer	p. 102
Large-Signal Simulations	p. 105
SSA at Work for the Buck Converter, the Linearization-Second Step	p. 106
SSA at Work for the Buck Converter, the Small-Signal Model-Final Step	p. 108
The PWM Switch Model-the Voltage-Mode Case	p. 111
Back to the Good Old Bipolars	p. 112
An Invariant Internal Architecture	p. 113
Waveform Averaging	p. 114
Terminal Currents	p. 116
Terminal Voltages	p. 117
A Transformer Representation	p. 117
Large-Signal Simulations	p. 118
A More Complex Representation	p. 121
A Small-Signal Model	p. 123
Helping with Simulation	p. 128
Discontinuous Mode Model	p. 129
Deriving the d[subscript 2] Variable	p. 132
Clamping Sources	p. 132
Encapsulating the Model	p. 134
The PWM Modulator Gain	p. 138
Testing the Model	p. 142
Mode Transition	p. 143
The PWM Switch Model-the Current-Mode Case	p. 145
Current-Mode Instabilities	p. 146
Preventing Instabilities	p. 151
The Current-Mode Model in CCM	p. 153
Upgrading the Model	p. 158
The Current-Mode Model in DCM	p. 161
Deriving the Duty Cycles d[subscript 1] and d[subscript 2]	p. 163
Building the DCM Model	p. 165
Testing the Model	p. 168
Buck DCM, Instability in DC	p. 172
Checking the Model in CCM	p. 172
The PWM Switch Model-Parasitic Elements Effects	p. 175
A Variable Resistor	p. 179
Ohmic Losses, Voltage Drops: The VM Case	p. 180
Ohmic Losses, Voltage Drops: The CM Case	p. 182
Testing the Lossy Model in Current Mode	p. 183
Convergence Issues with the CM Model	p. 186
PWM Switch Model in Borderline Conduction	p. 187
Borderline Conduction-the Voltage-Mode Case	p. 187
Testing the Voltage-Mode BCM Model	p. 191
Borderline Conduction-the Current-Mode Case	p. 194
Testing the Current-Mode BCM Model	p. 198
The PWM Switch Model-a Collection of Circuits	p. 202
The Buck	p. 203
The Tapped Buck	p. 204
The Forward	p. 205
The Buck-Boost	p. 206
The Flyback	p. 207
The Boost	p. 208
The Tapped Boost	p. 208
The Nonisolated SEPIC	p. 209
The Isolated SEPIC	p. 210
The Nonisolated Cuk Converter	p. 211
The Isolated Cuk Converter	p. 212
Other Averaged Models	p. 213
Ridley Models	p. 213
Small-Signal Current-Mode Models	p. 213
Ridley Models at Work	p. 214
CoPEC Models	p. 216
CoPEC Models at Work	p. 218
Ben-Yaakov Models	p. 220
What I Should Retain from Chap. 2	p. 224
References	p. 224
Basic Transfer Functions for Converters	p. 225
Buck	p. 226
Boost	p. 229
Buck-Boost	p. 231
References	p. 235
Poles, Zeros, and Complex Plane-a Simple Introduction	p. 235
References	p. 240
Feedback and Control Loops	p. 241
Observation Points	p. 243
Stability Criteria	p. 247
Phase Margin and Transient Response	p. 248
Choosing the Crossover Frequency	p. 249
Shaping the Compensation Loop	p. 250
The Passive Pole	p. 250
The Passive Zero	p. 251
Right Half-Plane Zero	p. 253
Type 1 Amplifier-Active Integrator	p. 255
Type 2 Amplifier-Zero-Pole Pair	p. 256
Type 2a-Origin Pole Plus a Zero	p. 258
Type 2b-Proportional Plus a Pole	p. 259
Type 3-Origin Pole Plus Two Coincident Zero-Pole Pairs	p. 261
Selecting the Right Amplifier Type	p. 262
An Easy Stabilization Tool-the k Factor	p. 263
Type 1 Derivation	p. 264
Type 2 Derivation	p. 264
Type 3 Derivation	p. 266
Stabilizing a Voltage-Mode Buck Converter with the k Factor	p. 267
Conditional Stability	p. 270
Independent Pole-Zero Placement	p. 272
Crossing Over Right at the Selected Frequency	p. 273
The k Factor Versus Manual Pole-Zero Placement	p. 275
Stabilizing a Current-Mode Buck Converter with the k Factor	p. 280
The Current-Mode Model and Transient Steps	p. 286
Feedback with the TL431	p. 286
A Type 2 Amplifier Design Example with the TL431	p. 291
A Type 3 Amplifier with the TL431	p. 292
Biasing the TL431	p. 298
The Resistive Divider	p. 303
The Optocoupler	p. 304
A Simplified Model	p. 305
Extracting the Pole	p. 306
Accounting for the Pole	p. 308
Shunt Regulators	p. 312
SPICE Model of the Shunt Regulator	p. 313
Quickly Stabilizing a Converter Using the Shunt Regulator	p. 314
Small-Signal Responses with PSIM and SIMPLIS	p. 316
What I Should Retain from Chap. 3	p. 322
References	p. 322
Automated Pole-Zero Placement	p. 323
A TL431 Spice Model	p. 326
A Behavioral TL431 Spice Model	p. 326
Cathode Current Versus Cathode Voltage	p. 328
Output Impedance	p. 329
Open-Loop Gain	p. 330
Transient Test	p. 331
Model Netlist	p. 331
Type 2 Manual Pole-Zero Placement	p. 332
Understanding the Virtual Ground in Closed-Loop Systems	p. 335
Numerical Example	p. 336
Loop Gain Is Unchanged	p. 337
Basic Blocks and Generic Switched Models	p. 341
Generic Models for Faster Simulations	p. 341
In-Line Equations	p. 341
Operational Amplifiers	p. 343
A More Realistic Model	p. 344
A UC384X Error Amplifier	p. 345
Sources with a Given Fan-Out	p. 348
Voltage-Adjustable Passive Elements	p. 349
The Resistor	p. 350
The Capacitor	p. 351
The Inductor	p. 353
A Hysteresis Switch	p. 355
An Undervoltage Lockout Block	p. 358
Leading Edge Blanking	p. 359
Comparator with Hysteresis	p. 361
Logic Gates	p. 362
Transformers	p. 364
A Simple Saturable Core Model	p. 366
Multioutput Transformers	p. 372
Astable Generator	p. 372
A Voltage-Controlled Oscillator	p. 374
A Voltage-Controlled Oscillator Featuring Dead Time Control	p. 377
Generic Controllers	p. 377
Current-Mode Controllers	p. 378
Current-Mode Model with a Buck	p. 380
Current-Mode Instabilities	p. 381
The Voltage-Mode Model	p. 382
The Duty Cycle Generation	p. 382
A Quick Example with a Forward Converter	p. 384
Dead Time Generation	p. 387
List of Generic Models	p. 387
Convergence Options	p. 388
What I Should Retain from Chap. 4	p. 391
References	p. 392
An Incomplete Review of the Terminology Used in Magnetic Designs	p. 392
Introduction	p. 392
Field Definition	p. 393
Permeability	p. 393
Founding Laws	p. 396
Inductance	p. 396
Avoiding Saturation	p. 397
References	p. 398
Feeding Transformer Models with Physical Values	p. 398
Understanding the Equivalent Inductor Model	p. 398
Determining the Physical Values of the Two-Winding T Model	p. 400
The Three-Winding T Model	p. 401
References	p. 405
Simulations and Practical Designs of Nonisolated Converters	p. 407
The Buck Converter	p. 407
A 12 V, 4 A Voltage-Mode Buck from a 28 V Source	p. 407
Ac Analysis	p. 410
Transient Analysis	p. 413
The Power Switch	p. 417
The Diode	p. 418
Output Ripple and Transient Response	p. 419
Input Ripple	p. 421
A 5 V, 10 A Current-Mode Buck from a Car Battery	p. 425
Ac Analysis	p. 426
Transient Analysis	p. 429
A Synchronous Buck Converter	p. 433
A Low-Cost Floating Buck Converter	p. 434
Component Constraints for the Buck Converter	p. 439
The Boost Converter	p. 441
A Voltage-Mode 48 V, 2 A Boost from a Car Battery	p. 441
Ac Analysis	p. 444
Transient Analysis	p. 449
A Current-Mode 5 V, 1 A Boost from a Li-Ion Battery	p. 452
Ac Analysis	p. 454
Transient Analysis	p. 459
Input Filter	p. 460
Component Constraints for the Boost Converter	p. 465
The Buck-Boost Converter	p. 465
A Voltage-Mode 12 V, 2 A Buck-Boost Converter Powered from a Car Battery	p. 465
Ac Analysis	p. 468
Transient Analysis	p. 474
A Discontinuous Current-Mode 12 V, 2 A Buck-Boost Converter Operating from a Car Battery	p. 476
Ac Analysis	p. 479
Transient Analysis	p. 483
Component Constraints for the Buck-Boost Converter	p. 486
References	p. 486
The Boost in Discontinuous Mode, Design Equations	p. 487
Input Current	p. 487
Output Ripple Voltage	p. 489
Simulations and Practical Designs of Off-Line Converters-The Front End	p. 491
The Rectifier Bridge	p. 491
Capacitor Selection	p. 493
Diode Conduction Time	p. 495
Rms Current in the Capacitor	p. 496
Current in the Diodes	p. 498
Input Power Factor	p. 498
A 100 W Rectifier Operated on Universal Mains	p. 499
Hold-Up Time	p. 501
Waveforms and Line Impedance	p. 502
In-Rush Current	p. 506
Voltage Doubler	p. 508
Power Factor Correction	p. 510
Definition of Power Factor	p. 512
Nonsinusoidal Signals	p. 512
A Link to the Distortion	p. 514
Why Power Factor Correction?	p. 515
Harmonic Limits	p. 517
A Need for Storage	p. 518
Passive PFC	p. 520
Improving the Harmonic Content	p. 524
The Valley-Fill Passive Corrector	p. 526
Active Power Factor Correction	p. 527
Different Techniques	p. 528
Constant On-Time Borderline Operation	p. 529
Frequency Variations in BCM	p. 531
Averaged Modeling of the BCM Boost	p. 532
Fixed-Frequency Average Current-Mode Control	p. 535
Shaping the Current	p. 540
Fixed-Frequency Peak Current-Mode Control	p. 543
Compensating the Peak Current-Mode Control PFC	p. 544
Average Modeling of the Peak Current-Mode PFC	p. 546
Hysteretic Power Factor Correction	p. 549
Fixed-Frequency DCM Boost	p. 550
Flyback Converter	p. 555
Testing the Flyback PFC	p. 559
Designing a BCM Boost PFC	p. 559
Average Simulations	p. 567
Reducing the Simulation Time	p. 570
Cycle-by-Cycle Simulation	p. 571
The Follow-Boost Technique	p. 574
What I Should Retain from Chap. 6	p. 575
References	p. 576
Simulations and Practical Designs of Flyback Converters	p. 579
An Isolated Buck-Boost	p. 579
Flyback Waveforms, No Parasitic Elements	p. 583
Flyback Waveforms with Parasitic Elements	p. 586
Observing the Drain Signal, No Clamping Action	p. 588
Clamping the Drain Excursion	p. 591
DCM, Looking for Valleys	p. 597
Designing the Clamping Network	p. 599
The RCD Configuration	p. 601
Selecting k[subscript c]	p. 604
Curing the Leakage Ringing	p. 605
Which Diode to Select?	p. 609
Beware of Voltage Variations	p. 610
TVS Clamp	p. 612
Two-Switch Flyback	p. 614
Active Clamp	p. 616
Design Example	p. 622
Simulation Circuit	p. 625
Small-Signal Response of the Flyback Topology	p. 628
DCM Voltage Mode	p. 628
CCM Voltage Mode	p. 635
DCM Current Mode	p. 636
CCM Current Mode	p. 638
Practical Considerations about the Flyback	p. 642
Start-Up of the Controller	p. 642
Start-Up Resistor Design Example	p. 644
Half-Wave Connection	p. 646
Good Riddance, Start-up Resistor!	p. 648
High-Voltage Current Source	p. 649
The Auxiliary Winding	p. 651
Short-Circuit Protection	p. 653
Observing the Feedback Pin	p. 654
Compensating the Propagation Delay	p. 655
Sensing the Secondary Side Current	p. 660
Improving the Drive Capability	p. 662
Overvoltage Protection	p. 663
Standby Power of Converters	p. 665
What Is Standby Power?	p. 666
The Origins of Losses	p. 666
Skipping Unwanted Cycles	p. 667
Skipping Cycles with a UC384X	p. 669
Frequency Foldback	p. 670
A 20 W, Single-Output Power Supply	p. 670
A 90 W, Single-Output Power Supply	p. 687
A 35 W, Multioutput Power Supply	p. 706
Component Constraints for the Flyback Converter	p. 725
What I Should Retain from Chap. 7	p. 726
References	p. 727
Reading the Waveforms to Extract the Transformer Parameters	p. 727
The Stress	p. 729
Voltage	p. 730
Current	p. 731
Transformer Design for the 90 W Adapter	p. 732
Core Selection	p. 732
Determining the Primary and Secondary Turns	p. 733
Choosing the Primary and Secondary Wire Sizes	p. 734
Choosing the Material, Based on the Desired Inductance, or Gapping the Core If Necessary	p. 735
Designs Using Intusoft Magnetic Designer	p. 735
Simulations and Practical Designs of Forward Converters	p. 739
An Isolated Buck Converter	p. 739
Need for a Complete Core Reset	p. 742
Reset Solution 1, a Third Winding	p. 746
Leakage Inductance and Overlap	p. 752
Reset Solution 2, a Two-Switch Configuration	p. 756
Two-Switch Forward and Half-Bridge Driver	p. 760
Reset Solution 3, the Resonant Demagnetization	p. 762
Reset Solution 4, the RCD Clamp	p. 767
Reset Solution 5, the Active Clamp	p. 778
Synchronous Rectification	p. 796
Multioutput Forward Converters	p. 799
Magnetic Amplifiers	p. 799
Synchronous Postregulation	p. 804
Coupled Inductors	p. 806
Small-Signal Response of the Forward Converter	p. 817
Voltage Mode	p. 817
Current Mode	p. 821
Multioutput Forward	p. 825
A Single-Output 12 V, 250 W Forward Design Example	p. 828
MOSFET Selection	p. 833
Installing a Snubber	p. 835
Diode Selection	p. 838
Small-Signal Analysis	p. 839
Transient Results	p. 841
Short-Circuit Protection	p. 846
Component Constraints for the Forward Converter	p. 849
What I Should Retain from Chap. 8	p. 849
References	p. 850
Half-Bridge Drivers Using the Bootstrap Technique	p. 851
Impedance Reflections	p. 855
Transformer and Inductor Designs for the 250 W Adapter	p. 859
Transformer Variables	p. 859
Transformer Core Selection	p. 859
Determining the Primary and Secondary Turns	p. 860
Choosing the Primary and Secondary Wire Sizes	p. 861
Gapping the Core	p. 861
Designs Using Intusoft Magnetic Designer	p. 862
Inductor Design	p. 865
Core Selection	p. 866
Choosing the Wire Size and Checking the DC Resistive Loss	p. 867
Checking the Core Loss	p. 867
Estimating the Temperature Rise	p. 867
CD-ROM Content	p. 868
Conclusion	p. 869
Index	p. 871
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