Power Supplies for LED Driving

Front-cover......Page 1
Front-matter......Page 2
Copyright......Page 5
Table of Contents......Page 6
Preface......Page 10
Objectives and General Approach......Page 11
Description of Contents......Page 12
Characteristics of LEDs......Page 16
Applications for LEDs......Page 17
Light Measure......Page 21
Equivalent Circuit to an LED......Page 22
Voltage Drop Versus Color and Current......Page 23
Common Mistakes......Page 24
Voltage Source......Page 25
Passive Current Control......Page 26
Active Current Control......Page 28
Detecting Failures......Page 31
Current Source......Page 32
Self-Adjusting Current Sharing Circuit......Page 33
Voltage Limiting......Page 35
Detecting LED Failures......Page 36
Zener Diodes as a Dummy Load......Page 37
Common Mistakes......Page 38
Conclusions......Page 39
Voltage Regulators......Page 40
Voltage Regulators as Current Source or Sink......Page 42
Constant Current Circuits......Page 43
Common Errors in Designing Linear LED Drivers......Page 44
Buck-Based LED Drivers......Page 46
An example Buck Converter Control IC......Page 47
Buck Circuits for DC Applications......Page 48
Choosing the Input Capacitor (C1)......Page 49
Choosing the Inductor (L1)......Page 50
Choosing the Sense Resistor (R2)......Page 51
Common Errors in Low Voltage Buck Design......Page 52
Buck Circuits for AC Input......Page 53
Choosing the Input Diode Bridge (D1) and the Thermistor (NTC)......Page 54
Choosing the Input Capacitors (C1 and C2)......Page 55
Choosing the Inductor (L1)......Page 56
Choosing the MOSFET (Q1) and Diode (D2)......Page 57
Choosing the Sense Resistor (R2)......Page 58
Buck Circuits Powered by an AC Phase Dimmer......Page 59
Common Errors in AC Input Buck Circuits......Page 61
Double Buck......Page 62
Hysteretic Buck......Page 66
Boost Converters......Page 68
 Boost Converter Operating Modes......Page 69
 HV9912 Boost Controller......Page 70
Design of a Continuous Conduction Mode Boost LED Driver......Page 74
 Typical Circuit......Page 75
 Computing the Input Inductor Value (L1)......Page 76
 Choosing the Switching MOSFET (Q1)......Page 77
 Choosing the Output Capacitor (Co)......Page 78
Choosing the Disconnect MOSFET (Q2)......Page 80
Choosing the Timing Resistor (RT)......Page 81
Choosing the Two Current Sense Resistors (R1 and R2)......Page 82
Programming the Slope Compensation (Rslope and R7)......Page 83
Setting the Inductor Current Limit (R5 and R6)......Page 84
Setting the Over-Voltage Trip Point (R8 and R9)......Page 85
Designing the Compensation Network......Page 86
Design of a Discontinuous Conduction Mode Boost LED Driver......Page 90
 Computing the Maximum Inductor Current (Iin max)......Page 91
 Computing the Input Inductor Value (L1)......Page 92
 Computing the On and Off Times of the Converter......Page 94
 Choosing the Output Capacitor (Co)......Page 95
Choose the Disconnect MOSFET (Q2)......Page 97
Choosing the Timing Resistor (RT)......Page 98
Choosing the Two Current Sense Resistors (R1 and R2)......Page 99
Setting the Inductor Current Limit (R5 and R6)......Page 100
 Setting the Over-Voltage Trip Point (R8 and R9)......Page 101
Designing the Compensation Network......Page 102
 Conclusions......Page 105
Boost-Buck Converter......Page 106
The Cuk Converter......Page 107
Operation of a Cuk Boost-Buck Converter......Page 108
Hysteretic Control of the Boost-Buck Converter......Page 110
The Effects of Delay in Hysteretic Control......Page 112
Stability of the Boost-Buck Converter......Page 115
Dimming Ratio Using PWM Dimming......Page 119
Specification......Page 120
Calculating the Duty Cycle......Page 121
Calculating the Output Inductor......Page 122
Calculating the Value of the Middle Capacitor (C1)......Page 124
Choosing the Switching Transistor (Q1)......Page 125
Choosing the Input Diode......Page 126
Calculating the Input Capacitance......Page 127
Calculating the Theoretical Switching Frequency Variation......Page 128
Internal Voltage Regulator of the HV9930......Page 129
Internal Voltage Reference......Page 130
Programming the Hysteretic Controllers and Over Voltage Protection......Page 131
Choosing the Output Side Resistors......Page 132
Design of the Input Side Resistors......Page 133
Improving Efficiency......Page 134
Meeting Conducted and Radiated EMI......Page 137
SEPIC Buck-Boost Converters......Page 138
Basic SEPIC Equations......Page 139
Common Mistakes in Boost-Buck Circuits......Page 146
Conclusions......Page 147
Power Factor Correction......Page 148
Bi-Bred......Page 149
Buck-Boost-Buck (BBB)......Page 151
Conclusions......Page 154
Fly-Back Converters......Page 155
Two Winding Fly-Back......Page 156
Fly-Back Example......Page 157
Design Rules for a Fly-Back Converter......Page 159
Case 2: Turns Ratio Based on Maximum Switch Voltage......Page 161
Inductance Calculations......Page 162
Single Winding Fly-Back (Buck-Boost)......Page 164
Linear Regulators......Page 167
Switching Regulators......Page 168
Buck Regulator Considerations......Page 169
Buck Converter AC Input Stage......Page 173
Boost Regulator Considerations......Page 174
Circuits with Power Factor Correction......Page 175
Fly-Back Converter Considerations......Page 176
Inrush Limiters......Page 178
Soft-Start Techniques......Page 179
Discrete Semiconductors......Page 181
MOSFETs......Page 183
Bipolar Transistors......Page 185
Diodes......Page 187
Capacitors......Page 188
Inductors......Page 193
Resistors......Page 196
The Printed Circuit Board (PCB)......Page 197
Surface Mount PCBs......Page 198
Operational Amplifiers and Comparators......Page 199
Magnetic Materials for Inductors and Transformers......Page 201
Iron Dust Cores......Page 203
Core Shapes and Sizes......Page 204
Magnetic Saturation......Page 205
Copper Losses......Page 206
EMI and EMC Issues......Page 209
AC Mains Connected LED Drivers......Page 210
Buck Circuit xample......Page 211
Cuk Circuit xample......Page 216
EMC Standards......Page 220
EMC Practices......Page 221
Efficiency and Power Loss......Page 223
Calculating Temperature......Page 224
Handling Heat - Cooling Techniques......Page 226
AC Mains Isolation......Page 230
Capacitor Ratings......Page 231
Low Voltage Operation......Page 232
Bibliography......Page 234
Index......Page 235
Author Biography......Page 237