Analog Circuit Design Volume Three (eBook)

Half Title 
2 
Analog Circuit Design Volume 2 4
Copyright 
5 
Dedication 1 
6 
Dedication 2 
8 
Contents 10
Publisher’s Note 26
Trademarks 34
Acknowledgments 36
Introduction 38
Foreword 40
PART 1 : Power Management 42
Section 1 : Power Management Design 
44 
1 High performance single phase DC/DC controller with power system management 46
Introduction 46
1.8V/30A single phase digital power supply with IIN sense 46
Input current sensing 47
Inductor DCR autocalibration 47
LTpowerPlay GUI 47
Conclusion 47
2 One device replaces battery charger, pushbutton controller, LED driver and voltage regulator ICs in portable electronics 48
Introduction 48
Pushbutton control 48
Battery, USB, wall and high voltage input sources 48
Battery charger 49
Three bucks, two LDOs and a boost/LED driver 49
Conclusion 49
3 Simple circuit replaces and improves on power modules at less than half the price 50
Introduction 50
100W isolated synchronous forward converter in an eighth brick footprint 51
This circuit is flexible 51
Conclusion 51
4 Wide input range, high efficiency DDR termination power supply achieves fast transient response 52
Introduction 52
Overview of the LTC3717 52
Design example 53
Conclusion 53
5 Minimize input capacitors in multioutput, high current power supplies 54
Introduction 54
Design details 54
Conclusion 55
6 Dual phase high efficiency mobile CPU power supply minimizes size and thermal stress 56
Introduction 56
Design example 57
Conclusion 57
7 SOT-23 SMBus fan speed controller extends battery life and reduces noise 58
Introduction 58
Boost-start timer, thermal shutdown and overcurrent clamp features 58
Conclusion 59
8 Active voltage positioning reduces output capacitors 60
Introduction 60
Basic principle 60
Basic implementation 61
Current mode control example—LTC1736 61
9 5V to 3.3V circuit collection 62
High efficiency 3.3V regulator 62
3.3V battery-powered supply with shutdown 62
3.3V supply with shutdown 62
LT1585 linear regulator optimized for desktop Pentium processor applications 62
LTC1148 5V to 3.38V Pentium power solution 3.5A output current 63
LTC1266 switching regulator converts 5V to 3.38V at 7A for Pentium and other high speed µPs 63
10 Hex level shift shrinks board space 64
Section 2 : Microprocessor Power Design 66
11 Cost-effective, low profile, high efficiency 42A supply powers AMD Hammer processors 68
Introduction 68
Design example 69
Conclusion 69
12 Efficient, compact 2-phase power supply delivers 40A to Intel mobile CPUs 70
Introduction 70
Smaller inductors, simplified thermal management 71
40A Intel IMVP-III voltage regulator 71
Conclusion 71
13 Microprocessor core supply voltage set by I2C bus without VID lines 72
Introduction 72
How it works 72
Why use an SMBus? 73
Desktop/portable VID DC/DC converter 73
14 High efficiency I/O power generation for mobile Pentium III microprocessors 74
15 PolyPhase sur.face mount power supply meets AMD Athlon processor requirements with no heat sink 76
Introduction 76
PolyPhase architecture 77
16 2-step voltage regulation improves performance and decreases CPU temperature in portable computers 78
1-step vs 2-step power conversion 78
Circuit description 79
Regulator efficiency considerations 79
17 Dual regulators power Pentium processor or upgrade CPU 80
A simple solution 80
Conclusion 81
Design equations 81
18 Big power for big processors: a synchronous regulator 82
LTC1430 performance features 82
A typical 5V to 3.3V application 83
19 High efficiency power sources for Pentium processors 84
Selection of input source 84
Transient response considerations 85
Circuit operation 85
20 Fast regulator paces high performance processors 86
21 Techniques for deriving 3.3V from 5V supplies 88
22 Regulator circuit generates both 3.3V and 5V outputs from 3.3V or 5V to run computers and RS232 90
Mixed 3.3V and 5V RS232 operation 91
Section 3 : Switching Regulator Basics 92
23 Tiny, highly flexible, dual boost/inverter tracks supplies 94
Introduction 94
LT3471 features 94
Easy-to-implement ±15V dual tracking supplies 94
Conclusion 95
24 Ultralow noise switching power supplies simplify EMI compliance 96
Introduction 96
Circuit description 96
Conclusion 97
25 Monolithic DC/DC converters break 1MHz to shrink board space 98
26 Capacitor and EMI considerations for new high frequency switching regulators 100
Capacitor technology considerations 100
Controlling EMI: conducted and radiated 101
27 Switching regulator generates both positive and negative supply with a single inductor 102
28 Floating input extends regulator capabilities 104
29 Programming pulse generators for flash memories 106
30 Achieving microamp quiescent current in switching regulators 108
31 Inductor selection for switching regulators 110
References 111
Section 4 : Switching Regulator Design: Buck (Step-Down) 112
32 Inverting DC/DC controller converts a positive input to a negative output with a single inductor 114
Advanced controller capabilities 114
-5.2V, 1.7A converter operates from a 4.5V to 16V source 114
High efficiency 115
Conclusion 115
33 20V, 2.5A monolithic synchronous buck SWITCHER+ with input current, output current and temperature sensing/limiting capabilities 116
Introduction 116
Output/input current sensing 117
Temperature sensing 117
Conclusion 117
34 1.5A rail-to-rail output synchronous step-down regulator adjusts with a single resistor 118
Introduction 118
Operation 118
Applications 119
Conclusion 119
35 42V, 2.5A synchronous step-down regulator with 2.5µA quiescent current 120
Introduction 120
High efficiency synchronous operation 120
Short-circuit robustness using small inductors 120
Current sense and monitoring with the LT8611 120
Wide input range operation at 2MHz 121
Low dropout operation 121
Conclusion 121
36 Bootstrap biasing of high input voltage step-down controller increases converter efficiency 122
Introduction 122
Employing EXTVCC to improve efficiency 122
Voltage doubler for output voltages below 4.7V 122
Conclusion 123
37 36V, 3.5A dual monolithic buck with integrated die temperature monitor and standalone comparator block 124
Introduction 124
High input voltage with high transient capability 124
On-die temperature monitoring 124
Standalone comparator block 125
Other features 125
Independent adjustable current limit 125
Independent synchronization 125
Frequency division 125
Conclusion 125
38 High efficiency, high density 3-phase supply delivers 60A with power saving Stage Shedding, active voltage positioning and nonlinear control for superior load step response 126
Introduction 126
1.5V/60A, 3-phase power supply 127
Conclusion 127
39 2-phase synchronous buck controller features light load Stage Shedding mode, active voltage positioning, low RSENSE and remote VOUT sensing 128
Introduction 128
High efficiency, 2-phase, 4.5V to 14V input, 1.5V/50A output converter 128
Stage Shedding mode 129
Active voltage positioning 129
Inductor DCR sensing temperature compensation 129
Output voltage remote sensing 129
Conclusion 129
40 Dual output high efficiency converter produces 3.3V and 8.5V outputs from a 9V to 60V rail 130
Introduction 130
Feature rich 130
Dual output application 131
Single output application 131
Conclusion 131
41 Dual output step-down controller produces 10% accurate, efficient and reliable high current rails 132
Introduction 132
1.5V/20A and 1.2V/20A buck converter with remote sensing and NTC compensated DCR sensing 133
PolyPhase operation 133
Other important features 133
Conclusion 133
42 15VIN, 4MHz monolithic synchronous buck regulator delivers 5A in 4mm.×.4mm QFN 134
Introduction 134
1.8VOUT, 2.25MHz buck regulator 134
1.2VOUT, 10A, dual phase supply 135
Conclusion 135
43 Dual output buck regulator with current partitioning optimizes efficiency in space-sensitive applications 136
Introduction 136
Flexible current partitioning 137
Operation modes and efficiency 137
Application examples 137
Conclusion 137
44 Triple buck regulator features 1-wire dynamically programmable output voltages 138
Introduction 138
Three individually programmable bucks 138
Configure parallel power stages for different loads 138
Power good indicator 139
Power saving operating modes 139
Programmable clock frequency 139
2-output, individually programmable 1.2A regulators 139
Conclusion 139
45 Buck conver.ter eases the task of designing auxiliary low voltage negative rails 140
Introduction 140
Leave the transformer alone: -3.3VOUT from -12VIN 140
Conclusion 141
46 Monolithic synchronous step-down regulator delivers up to 12A from a wide input voltage range 142
Introduction 142
Typical application example 142
Paralleling regulators for > 12A
Conclusion 143
47 Step-down synchronous controller operates from inputs down to 2.2V 144
Introduction 144
“Dying gasp” applications 144
Generate a negative voltage from a low positive VIN 145
Wide input voltage range 145
Conclusion 145
48 Compact I2C-controllable quad synchronous step-down DC/DC regulator for power-conscious portable processors 146
Introduction 146
Four I2C-controllable regulators 146
Power saving operating modes 146
I2C programming of output voltages allows easy sequencing, tracking and margining 147
Conclusion 147
49 Compact triple step-down regulator offers LDO driver and output tracking and sequencing 148
Introduction 148
6V to 36V input to four outputs—1.8V, 3.3V, 5V and 2.5V—one IC 148
Low ripple high frequency operation even at high VIN/VOUT ratios 148
Input voltage lockout and sequencing 149
Conclusion 149
50 A positive-to-negative voltage converter can be used for stable outputs even with a widely varying input 150
Basic operation 150
Component stress in a positive-to-negative topology 151
Circuit description 151
Conclusion 151
51 One IC generates three sub-2V power rails from a Li-Ion cell 152
Introduction 152
Triple supply in a tiny package 152
High efficiency and low noise 152
Selectable Burst Mode operation or pulse-skipping at light load 153
Very low dropout (VLDO) linear regulators 153
Power good detection 153
Conclusion 153
52 36V 2A buck regulator integrates power Schottky 154
Introduction 154
A small, simple solution 154
Low ripple and high efficiency solution over a wide load range 155
Frequency foldback saves chips 155
Conclusion 155
53 Triple output 3-phase controller saves space and improves per.formance in high density power converters 156
Conclusion 157
54 Dual monolithic step-down switching regulator provides 1.6A outputs with reduced EMI and VOUT as low as 0.8V 158
Introduction 158
Typical LT3506A and LT3506 applications 158
Power sequencing without adding components 159
2-phase switching eases EMI concerns 159
Conclusion 159
55 A compact dual step-down converter with VOUT tracking and sequencing 160
Introduction 160
LT3501 dual converter features 160
Output supply tracking and sequencing 161
High current single VOUT, low ripple 6A output 161
56 Tiny monolithic step-down regulators operate with wide input range 162
Introduction 162
Low ripple and high efficiency solution over wide load range 162
Small solution size 163
Additional features of LT3481 and LT3493 163
Conclusion 163
57 Cascadable 7A point-of-load monolithic buck converter 164
Introduction 164
Features 164
Operation 164
Greater than 7A outputs 165
Conclusion 165
58 High voltage current mode step-down conver.ter with low power standby capability 166
Introduction 166
High efficiency at standby 166
12V/75W synchronous buck DC/DC converter 167
59 Low EMI synchronous DC/DC step-down controllers offer programmable output tracking 168
Introduction 168
Three choices for start-up control 168
Low EMI DC/DC conversion 169
Conclusion 169
60 ThinSOT micropower buck regulator has low output ripple 170
Introduction 170
Current mode control 170
Design flexibility with integrated boost diode 171
Conclusion 171
61 Tiny versatile buck regulators operate from 3.6V to 36V input 172
Introduction 172
Small size and versatility 172
LT1936 produces 3.3V at 1.2A from 4.5V to 36V 172
Producing a lower output voltage from the LT1936 172
Negative output from a buck regulator 173
Tiny circuit generates 3.3V and 5V from a minimum 4.5V supply 173
Conclusion 173
62 High accuracy synchronous step-down controller provides output tracking and programmable margining 174
Introduction 174
Start-up and shutdown output tracking 175
Programmable voltage margining 175
Additional features 175
Conclusion 175
63 60V, 3A step-down DC/DC converter has low dropout and 100µA quiescent current 176
Introduction 176
Burst Mode operation 177
Low dropout 177
Soft-start 177
Power good 177
Conclusion 177
64 Monolithic synchronous regulator drives 4A loads with few external components 178
Introduction 178
High efficiency 2.5V/4A step-down regulator 179
High efficiency 3.3V/4A step-down regulator with all ceramic capacitors 179
Conclusion 179
65 High performance power solutions for AMD Opteron and Athlon 64 processors 180
Introduction 180
3-phase, 65A AMD VRM design 181
Conclusion 181
66 High current step-down controller regulates to 0.6V output from 3V input 182
Introduction 182
Design examples 182
Conclusion 183
67 Efficient dual polarity output converter fits into tight spaces 184
Introduction 184
12V input, ±5V output, only 3mm high 184
Typical bucks with second, negative outputs 184
Conclusion 185
68 Dual output supply powers FPGAs from 3.3V and 5V inputs 186
Introduction 186
Circuit description 186
Conclusion 187
69 3A, 2MHz monolithic synchronous step-down regulator provides a compact solution for DDR memory termination 188
Introduction 188
3A, 2.5V to 1.25V step-down DC/DC converter 188
Conclusion 189
70 60V/3A step-down DC/DC converter maintains high efficiency over a wide input range 190
Introduction 190
Efficiency 190
Small size, low output ripple voltage (high switching frequency, all ceramic solution) 191
Peak switch current (not your average current mode converter) 191
Conclusion 191
71 Monolithic synchronous step-down regulators pack 600mA current rating in a ThinSOT package 192
Introduction 192
Space saving 192
Versatile 192
Fault protection 193
Efficient Burst Mode operation (LTC3406 series) 193
Pulse-skipping mode (LTC3406B series) for low noise 193
1.8V/600mA step-down regulator using all ceramic capacitors 193
Efficiency considerations 193
72 High efficiency adaptable power supply for XENPAK 10Gb/s Ethernet transceivers 194
Introduction 194
Adaptable power supply 194
Conclusion 195
73 High voltage buck regulators provide high current, low profile power solutions for FireWire peripherals 196
Introduction 196
Circuit descriptions 196
Conclusion 197
74 Efficient DC/DC converter provides two 15A outputs from a 3.3V backplane 198
Introduction 198
Design example 199
Conclusion 199
75 60V step-down DC/DC conver.ter maintains high efficiency 200
Introduction 200
Efficiency 200
Output ripple voltage 201
Peak switch current 201
LT1766 features 201
76 Tiny buck regulator accepts inputs from 3.6V to 25V and eliminates heat sink 202
Introduction 202
Complete switcher in ThinSOT results in compact solution 202
The LT1616 produces 3.3V at 400mA 203
Ceramic capacitors are best 203
Smaller than a TO-220 203
2.5V output 203
77 1.4MHz switching regulator draws only 10µA supply current 204
Introduction 204
LTC3404 features 204
3.1V/600mA step-down regulator 204
Externally synchronized 3.1V/600mA step-down regulator 205
Conclusion 205
78 10µA quiescent current step-down regulators extend standby time in handheld products 206
Importance of low quiescent current 206
LTC1878 single Li-Ion to 2.5V regulator 206
LTC1771 3.3V/2A regulator 207
Low operating current without compromising transient response 207
79 Low cost PolyPhase DC/DC converter delivers high current 208
Introduction 208
Design example 209
Overcurrent limit 209
Multiphase applications 209
Conclusion 209
80 Unique high efficiency 12V converter operates with inputs from 6V to 28V 210
12V output, single inductor, buck/boost converter 210
Synchronous circuit for higher power, higher VIN 211
81 Low cost, high efficiency 42A DC/DC converter 212
Introduction 212
Design example 213
Conclusion 213
82 High efficiency PolyPhase converter uses two inputs for a single output 214
Introduction 214
Design details 214
A typical application 215
Test results 215
Conclusion 215
83 High current dual DC/DC converter operates from 3.3V input 216
84 Low cost surface mount DC/DC converter delivers 100A 218
Introduction 218
Design details 218
Conclusion 219
85 high voltage, low noise buck switching regulator 220
Generating low noise, dual-voltage supplies 221
86 Low cost, high efficiency 30A low profile PolyPhase converter 222
Overview of the LTC1629 222
Design example: 30A 2-phase power supply 223
Conclusion 223
87 2-phase switching regulator fits in tight places 224
88 Low dropout 550kHz DC/DC controller operates from inputs as low as 2V 226
2.5V, 4A buck DC/DC converter 226
“Zeta” step-up/step-down converter 227
89 Switching regulator controllers set a new standard for transient response 228
90 60V, high efficiency buck switching regulators in SO-8 230
Generating low cost, dual-voltage supplies 231
Conclusion 231
91 High efficiency, monolithic synchronous step-down regulator works with single or dual Li-Ion batteries 232
Single Li-Ion applications 232
Auxiliary winding control using SYNC/FCB pin 233
92 A low cost, efficient mobile CPU power 234
93 Optimizing a DC/DC converter’s output capacitors 236
94 Step-down converter operates from single Li-Ion cell 238
Introduction 238
Single-cell Li-Ion operation 238
100% duty cycle in dropout mode 239
High efficiency 5V to 3.3V conversion 239
Current mode architecture 239
Low voltage low RDS(ON) switch 239
Conclusion 239
95 Optimized DC/DC converter loop compensation minimizes number of large output capacitors 240
External loop compensation can save money 240
Loop compensation using a dynamic load 241
96 A high efficiency 500kHz, 4.5A step-down converter in an SO-8 package 242
High efficiency, 25V, 0.07O switch 242
4.5A in an SO-8 243
Dual output SEPIC converter 243
97 High efficiency switching regulators draw only 10µA supply current 244
Inductor current control 244
3.3V/250mA step-down regulator 244
3.3V/10mA regulator from a 4mA to 20mA loop 245
Pushbutton ON/OFF operation 245
98 High power synchronous buck converter delivers up to 50A 246
Introduction 246
Distributed power 246
Higher input voltages 247
Blame it on the physicists 247
99 Single IC, five output switching power supply system for portable electronics 248
100 Low noise switching regulator helps control EMI 250
New IC solves old problems 250
New feature provides new EMI control 250
Additional features 251
101 Efficient processor power system needs no heat sink 252
New IC powers portable Pentium processor and much more 252
High performance Pentium processor power 253
Portable Pentium processor power 253
102 A new, high efficiency monolithic buck converter 254
Efficiency 254
High frequency operation 254
Constant off-time architecture 255
100% duty cycle in dropout mode 255
Good start-up and transient behavior 255
2.5mm typical height 5V-to-3.3V regulator 255
Conclusion 255
103 Switching regulator provides high efficiency at 10A loads 256
N-channel vs P-channel 256
Driving N-channel MOSFETs 256
Basic circuit configurations 257
Conclusion 257
104 Dual output regulator uses only one inductor 258
Regulation performance and efficiency 258
Output ripple voltage 259
105 Highly integrated high efficiency DC/DC conversion 260
LTC1574 260
Low noise regulator 260
LTC1265 261
Battery charger application 261
LTC1574 or LTC1265? 261
106 Ultralow power, high efficiency DC/DC converter operates outside the audio band 262
107 Triple output 3.3V, 5V, and 12V high efficiency notebook power supply 264
108 Single device provides 3.3V and 5V in surface mount 266
Customizing the circuit 267
Construction notes 267
Other 267
109 A simple high efficiency, step-down switching regulator 268
100% duty cycle in dropout 269
Positive-to-negative converter 269
110 Delivering 3.3V and 5V at 17W 270
Performance 270
Theory of operation 270
Circuit particulars 271
111 Low parts count DC/DC converter circuit with 3.3V and 5V outputs 272
Performance 272
Inductor 272
Capacitors 272
Layout 273
Heat sinking 273
112 New synchronous step-down switching regulators achieve 95% efficiency 274
113 High performance frequency compensation gives DC-to-DC converter 75µs response with high stability 276
Inductors 276
Capacitors 276
Layout 277
Output adjustment 277
Heat sinking 277
Section 5 : Switching Regulator Design: Boost Converters 278
114 1µA IQ synchronous boost converter extends battery life in portable devices 280
Introduction 280
1.8V to 5.5V input to 12V output boost regulator 280
Output disconnect 281
Start-up inrush current limiting 281
Conclusion 281
115 Ultralow power boost converters require only 8.5µA of standby quiescent current 282
Introduction 282
Application example 282
Ultralow quiescent current boost converter with output disconnect 282
Compatible with high impedance batteries 283
Conclusion 283
116 Tiny dual full-bridge Piezo motor driver operates from low input voltage 284
Introduction 284
Single driver application 284
Using external power supply 285
Operating Piezo motor with long wires 285
Conclusion 285
117 Tiny synchronous step-up converter starts up at 700mV 286
Introduction 286
Conclusion 287
118 High efficiency 2-phase boost converter minimizes input and output current ripple 288
Introduction 288
Conclusion 289
119 ThinSOT switching regulator controls inrush current 290
Introduction 290
A simple solution 290
Conclusion 291
120 Dual DC/DC converter with integrated Schottkys generates ±40V outputs and consumes only 40µA quiescent current 292
Introduction 292
Dual output ±20V converter 292
Dual output (±40V) converter 293
CCD sensor bias supply 293
Conclusion 293
121 Compact step-up converter conserves battery power 294
Introduction 294
16V bias supply 294
20V bias supply with variable output voltage 295
±20V bias supply 295
34V bias supply 295
Conclusion 295
122 2-phase boost converter delivers 10W from a 3mm.×.3mm DFN package 296
Introduction 296
Dual phase converter reduces output ripple 296
Smaller layout is possible by reducing the number of external components 297
Antiringing feature in discontinuous operation 297
Conclusion 297
123 4-phase monolithic synchronous boost converter delivers 2.5A with output disconnect in a 5mm.×.5mm QFN package 298
Introduction 298
Multiple operating modes optimize performance in different applications 298
Fault protection 299
High power and high efficiency in a small package 299
Conclusion 299
124 Boost regulator makes low profile SEPIC with both step-up and step-down capability 300
Introduction 300
3V to 20V input, 5V output, 3mm maximum height SEPIC 300
4V to 18V input, 12V output, 3mm maximum height SEPIC 301
Conclusion 301
125 Dual monolithic buck regulator provides two 1.4A outputs with 2-phase switching to reduce EMI 302
Introduction 302
Circuit description 302
High frequency, current mode switching minimizes component size 303
2-phase switching eases EMI concerns 303
Soft-start and power good pins simplify supply sequencing 303
Conclusion 303
126 4MHz monolithic synchronous step-down regulators bring high efficiency to space-sensitive applications 304
Introduction 304
Multiple operating modes allow optimization of efficiency and noise suppression 304
Two 2.5V step-down converters 305
Conclusion 305
127 Tiny and efficient boost converter generates 5V at 3A from 3.3V bus 306
Introduction 306
3.3V input, 5V/3A output boost regulator 306
2-cell input, 3.3V/1A output regulator 307
Conclusion 307
128 Tiny boost controller provides efficient solutions for low voltage inputs 308
Introduction 308
3.3V to 5V converters 308
Choosing the MOSFET 309
Automotive supply 309
Conclusion 309
129 Current-limited DC/DC converter simplifies USB power supplies 310
USB to 12V boost converter 310
USB to 5V SEPIC DC/DC converter with short-circuit protection 310
Li-Ion white LED driver 311
130 3MHz micropower synchronous boost converters deliver 3W from two cells in a tiny MSOP package 312
All-ceramic-capacitor, 2-cell to 3.3V, 1A converter 312
High efficiency Li-Ion CCFL backlight application 313
131 SOT-23 switching regulator with integrated 1A switch delivers high current outputs in a small footprint 314
5V local supply 314
12V local supply 315
±15V dual output converter with output disconnect 315
132 A 500kHz, 6A monolithic boost converter 316
Circuit description 316
5V to 12V boost converter 316
Positive to negative converter 317
5V SEPIC converter 317
Conclusion 317
133 Micropower 600kHz step-up DC/DC converter delivers 5V at 1A from a li-Ion cell 318
Single Li-ion cell to 5V/1A DC/DC converter for GSM 318
2-cell digital camera supply produces 3.3V, 5V, 18V and -10V 319
134 Ultralow noise switching regulator controls EMI 320
Low noise boost regulator 320
Low noise bipolar supply 321
Additional LT1534 features 321
135 Off-line low noise power supply does not require filtering to meet FCC emission requirements 322
Introduction 322
Circuitry details 323
Performance characteristics 323
136 “LCD bias” and “backup supply” applications for a micropower DC/DC converter 324
2-cell, low profile LCD bias generator fits in small places 324
Supercapacitor-powered backup supply 325
137 Short-circuit protection for boost regulators 326
Short-circuit protection and load disconnect with the LTC1477 326
Current-limited boost regulator 326
Short-circuit protection at higher power 327
138 Single-cell micropower fixed-frequency DC/DC converter needs no electrolytic capacitors 328
Single-cell boost converter 328
455kHz noise considerations 329
139 2 AA cells replace 9V battery, extend operating life 330
140 A simple, surface mount flash memory Vpp generator 332
141 No design switching regulator 5V, 5A buck (step-down) regulator 334
Introduction 334
Circuit description 334
Conclusion 334
Section 6 : Switching Regulator Design: DC/DC Controllers 336
142 Dual controller provides 2µs step response and 92% efficiency for 1.5V rails 338
Introduction 338
1.5V/25A and 1.2V/25A buck converter 339
Detect transient feature further speeds up transient response 339
Conclusion 339
143 Dual DC/DC controller for DDR power with differential VDDQ sensing and ±50mA VTT reference 340
Introduction 340
High efficiency, 4.5V to 14V input, dual output DDR power supply 340
Load-release transient detection 340
VTT reference (VTTR) 341
VTT supply 341
Conclusion 341
144 Single resistor sets positive or negative output for DC/DC converter 342
Introduction 342
Sensing output voltage has never been easier 342
Adjustable/synchronizable switching frequency 342
Soft-start and undervoltage lockout 342
Boost converters 343
Cuk converter 343
SEPIC converters 343
Conclusion 343
145 Multiphase DC/DC controller pushes accuracy and bandwidth limits 344
Introduction 344
A dual output, 2-phase supply with differential remote sensing and inductor DCR sensing 344
A tried-and-true architecture 345
Load step improvement with voltage positioning 345
Conclusion 345
146 2-phase DC/DC controller makes fast, efficient and compact power supplies 346
147 High performance 3-phase power supply delivers 65A and high efficiency over the entire load range 348
Introduction 348
Stage Shedding operation 349
3-phase high efficiency VRM9.x power supplies for Pentium 4 CPU 349
148 Reduce component count and improve efficiency in SLIC and RF power supplies 350
Introduction 350
A dual output SLIC supply with simplified feedback using the LTC3704 350
Improved battery protection using the LTC3704’s programmable undervoltage lockout 351
A current mode, -8.0V, 1.2A RF power supply with no current sense resistor 351
149 SOT-23 DC/DC converters generate up to ±35V outputs and consume only 20µA of quiescent current 352
±20V dual output converter with output disconnect 352
24V boost converter 353
1V to 35V boost converter 353
1-cell to 3V boost converter 353
Section 7 : Switching Regulator Design: Buck-Boost Controllers 354
150 80V synchronous 4-switch buck-boost controller delivers hundreds of watts with 99% efficiency 356
Introduction 356
240W 48V 5A telecom power supply 356
500W charger for 12S liFePO4 battery 357
Four servo loops and wide voltage range 357
Conclusion 357
151 Wide input voltage range boost/inverting/SEPIC controller works down to an input voltage of 1.6V 358
Introduction 358
Wide input voltage range with internal LDO 358
Sensing output voltage made easier 358
Adjustable/synchronizable switching frequency 359
Precision UVLO and soft-start 359
A 2.5V to 15V to 12V SEPIC converter 359
A 1.8V to 4.5V to 5V/2A boost converter 359
Conclusion 359
152 High efficiency 4-switch buck-boost controller provides accurate output current limit 360
Introduction 360
LTC3789 features 360
12V, 5A output from a 4V to 38V input 360
Accurate output (or input) current limit 361
Conclusion 361
153 Buck-boost controller simplifies design of DC/DC converters for handheld products 362
Introduction 362
High efficiency controller capabilities 362
3.3V, 3A converter operates from 2.7V–10V source 363
95% efficiency 363
Conclusion 363
154 Wide input voltage range buck-boost converter simplifies design of variable input supplies 364
Introduction 364
Efficiency 365
Programmable Burst Mode operation 365
1.27mm profile Li-Ion to 3.3V regulator 365
Conclusion 365
155 Buck or boost: rugged, fast 60V synchronous controller does both 366
Introduction 366
Feature rich controller 366
High efficiency 48V to 3.3V/6A power supply 366
High efficiency 12V to 24V/5A synchronous step-up fan power supply 367
156 Industry’s first 4-switch buck-boost controller achieves highest efficiency using a single inductor 368
Introduction 368
High efficiency 4-switch buck-boost converter 368
Replacing a SEPIC converter 369
Protection for boost operation 369
Simplify 369
Conclusion 369
157 High input voltage monolithic switcher steps up and down using a single inductor 370
Introduction 370
4V–60V input to 5V output DC/DC automotive converter 370
8V–60V input to 12V output DC/DC converter 371
Conclusion 371
158 Supply 2A pulses for GSM transmission from 500mA USB or PCMCIA ports 372
Introduction 372
Powering GSM modems from USB or PCMCIA 372
5V converter in USB On-The-Go devices 373
Conclusion 373
159 Micropower buck/boost circuits: converting three cells to 3.3V 374
160 250kHz, 1mA IQ constant frequency switcher tames portable systems power 376
3.3V SEPIC converter 376
Dual output converter 377
161 DC/DC converters for portable computers 378
162 No design switching regulator 5V buck-boost (positive-to-negative) regulator 380
Introduction 380
Circuit description 380
Conclusion 380
Section 8 : Linear Regulator Design 382
163 High voltage inverting charge pump produces low noise positive and negative supplies 384
Introduction 384
Inverting charge pump 384
Constant frequency mode 384
Burst mode operation 385
Dual LDOs 385
Conclusion 385
164 80V linear regulator is micropower 386
Introduction 386
Introducing the LT3010 high voltage LDO 386
A versatile and rugged regulator 387
Conclusion 387
165 Very low dropout (VLDO) linear regulators supply low voltage outputs 388
Introduction 388
VLDO circuit descriptions 388
Conclusion 389
166 Lowest noise SOT-23 LDOs have 20µA quiescent current, 20µVRMS noise 390
Applying the regulators 390
Noise performance 390
Other advantages 391
Conclusion 391
167 High efficiency linear and switching solutions for splitting a digital supply 392
168 UltraFast linear regulator eliminates all bulk tantalum and electrolytic output capacitors 394
Introduction 394
New LTC regulator controllers 394
Conclusion 395
169 Fast response low dropout regulator achieves 0.4 dropout at 4A 396
Enter the LT1580 396
The LT1580 brings many new features 396
Circuit example 397
170 Create a virtual ground with a sink/source voltage regulator 398
171 5V to 3.3V regulator with fail-safe switchover 400
172 A simple ultralow dropout regulator 402
173 Powering 3.3V digital systems 404
Regulator design 405
174 A simple ultralow dropout regulator 406
Section 9 : Micromodule (µModule) Power Design 408
175 Dual 13A µModule regulator with digital interface for remote monitoring & control of power
Digital power system management: set, monitor, change and log power 410
Dual µModule regulator with precision READ/WRITE of power parameters 410
Internal or external compensation 411
Current share for up to 100A at 1VOUT 411
Conclusion 411
176 36V input, low output noise, 5A µModule regulator for precision data acquisition systems 412
Introduction 412
Integrated switching and linear regulators 412
PCB trace voltage compensation using SENSEP 412
Programmable output voltage 412
DC1738A highlights the LTM8028 capabilities 413
Noise test comparison using LTC2185 ADC 413
Conclusion 413
177 Step-down µModule regulator produces 15A output from inputs down to 1.5V—no bias supply required 414
15A high efficiency output from a low input voltage 414
Input and output ripple 414
Thermally enhanced packaging 415
Conclusion 415
178 Dual µModule DC/DC regulator produces high efficiency 4A outputs from a 4.5V to 26.5V input 416
Dual system-in-a-package regulator 416
Multiphase operation for four or more outputs 417
Thermal performance 417
Conclusion 417
179 Triple output DC/DC µModule regulator in 15mm.×.15mm.×.2.8mm surface mount package replaces up to 30 discrete components 418
Introduction 418
Dual switching 4A and 1.5A VLDO regulators 418
Multiple low noise outputs 418
Thermally enhanced packaging 419
Output voltage tracking 419
180 Dual 8A DC/DC µModule regulator is easily paralleled for 16A 420
Two independent 8A regulator systems in a single package 420
Simple and efficient 420
Parallel operation for increased output current 421
Conclusion 421
181 µModule buck-boost regulators offer a simple and efficient solution for wide input and output voltage range applications 422
Introduction 422
High efficiency 422
Low profile solution 422
Smooth transition and circuit simplicity 422
Excellent thermal performance 423
Conclusion 423
182 8A low voltage, low profile DC/DC µModule regulator in 9mm.×.15mm package weighs only 1g 424
Introduction 424
8A DC/DC µModule regulator in an IC form factor 424
Wealth of features 424
Quick and easy design 425
Thermally enhanced packaging 425
Output voltage tracking 425
Current sharing: 8A.+.8A.=.16A 425
Fault conditions: overcurrent limit and thermal shutdown 425
Conclusion 425
183 Simple and compact 4-output point-of-load DC/DC µModule system 426
Introduction 426
4-output DC/DC converter power system 426
Output tracking 427
Frequency synchronization 427
Conclusions 427
184 10A high performance point-of-load DC/DC µModule regulator 428
Introduction 428
10A DC/DC µModule regulator in IC form factor 428
Quick and easy design 428
Thermally enhanced packaging 429
Fast transient response 429
Paralleling the µModule regulator for 20A output 429
Section 10 : Switching Regulators for Isolated Power Design 430
185 Isolated converters have buck simplicity and performance 432
Simple isolated 3.3V, 30A forward converter 432
PolyPhase design ups power limit 433
Related products 433
Features 433
Conclusion 433
186 Multiple output isolated power supply achieves high efficiency with secondary side synchronous post regulator 434
Introduction 434
Design example 434
Conclusion 434
187 Chip set offers low cost alternative to 48V telecom modules 436
Isolated 48V to 3.3V supply 436
Conclusion 436
188 5V high current step-down switchers 438
Low cost high efficiency (80%), high power density DC/DC converter 438
Synchronous switching eliminates heat sinks in a 50W DC/DC converter 439
Section 11 : Power Control & Ideal Diode Design
189 Ideal diodes protect against power supply wiring errors 442
Introduction 442
Types of misconnections 442
Conclusion 443
190 Ideal diode controller eliminates energy wasting diodes in power OR-ing applications 444
Introduction 444
Automatic power switching between two power sources 444
Load sharing 445
Conclusion 445
191 Replace ORing diodes with MOSFETs to reduce heat and save space 446
Introduction 446
Ideal -48V ORing diode 446
Fault output detects damaged MOSFETs and fuses 447
Positive low voltage ideal diodes 447
Conclusion 447
192 Dual monolithic ideal diode manages multiple power inputs 448
Introduction 448
Triple supply power management 448
Automatic switchover between a battery and a wall adapter with a battery charger 449
Conclusion 449
193 PCMCIA socket voltage switching 450
Introduction 450
LTC1472: complete VCC and VPP PCMCIA switch matrix with SafeSlot protection 451
Conclusion 451
194 PC card power management techniques 452
Section 12 : Battery Management 454
195 Complete battery charger solution for high current portable electronics 456
Introduction 456
Input multiplexer 456
Dual high current input application 457
0V ~6V input on either WALL or USB 457
> 6V input on either WALL or USB
< 0V input on either WALL or USB
OTG operation 457
Conclusion 457
196 Battery conditioner extends the life of Li-Ion batteries 458
Introduction 458
The underlying aging process in Li-Ion batteries 458
Conditions that affect the aging process 459
Battery conditioner avoids conditions that accelerate aging 459
Conclusion 459
197 Simple calibration circuit maximizes accuracy in Li-Ion battery management systems 460
Introduction 460
Accounting for the error sources 460
Examining calibration strategies 461
Conclusion 461
Reference 461
198 USB power solution includes switching power manager, battery charger, three synchronous buck regulators and LDO 462
Introduction 462
Switching PowerPath controller maximizes available power to the system load 462
Complete power solution in a single IC 463
Conclusion 463
199 Switching USB power manager with PowerPath control offers fastest charge time with lowest heat 464
Introduction 464
PowerPath controllers deliver more power to the system load 464
LTC4088 makes charging more efficient 465
LTC4088 reduces USB charge time 465
LTC4088 eases thermal constraints 465
Conclusion 465
200 Universal Li-Ion battery charger operates from USB and 6V to 36V input in just 2cm2 466
Introduction 466
Adaptive high voltage buck minimizes total power loss 467
USB power manager maximizes power available to the system 467
Small footprint 467
Summary 467
201 Handheld high power battery charger 468
Introduction 468
Small PCB footprint 468
Advanced features and functions 469
Flexible options 469
Conclusion 469
202 Fast, high efficiency, standalone NiMH/NiCd battery charging 470
Introduction 470
NiCd./NiMH battery charging basics 470
Complete 4-cell NiMH battery charger 471
Standalone charge termination 471
Conclusion 471
203 Dual Smart Battery charger simplifies battery backup for servers 472
Introduction 472
LTC1760 dual smart battery charger 472
LTC1760 power management 473
204 Advanced topology USB battery charger optimizes power utilization for faster charging 474
Benefits of the LTC4055 474
Simple circuit automatically selects the best power source 475
Operation with wall adapter present 475
Operation with no wall adapter, but USB available 475
Unplugged operation 475
Conclusion 475
205 Simplify battery charging from the USB 476
Introduction 476
Charging from USB or a wall adapter 477
Faster charging with system in full operation 477
206 Li-Ion linear charger allows fast, full current charging while limiting PC board temperature to 85°C 478
Introduction 478
Thermal feedback loop limits IC temperature 478
Charge cycle with thermal limit in operation 478
Thermally enhanced package dramatically improves power dissipation 479
Complete standalone charger 479
Conclusion 479
207 Dual battery power manager increases run time by 12% and cuts charge time in half 480
Introduction 480
Automatic current sharing 481
Simultaneous discharge increases run time 481
Faster charge times with a second battery 481
Automatic crisis power management 481
Conclusion 481
208 Single inductor, tiny buck-boost converter provides 95% efficiency in lithium-ion to 3.3V applications 482
Introduction 482
All ceramic capacitor, single inductor, 2W Li-Ion to 3.3V converter 482
WCDMA dynamically controlled power amp power supply 483
209 Tiny step-up/step-down power supply delivers 3.3V at 1.3A in battery-powered devices 484
Introduction 484
Regulated output voltage from a range of inputs 484
Highly efficient 485
210 A very low cost SOT-23 Li-Ion battery charger requires little area and few components 486
A simple low cost Li-Ion charger 486
A programmable constant current source 487
211 Simple Li-Ion charge termination using the LT1505 488
212 Li-Ion charge termination IC interfaces with PWM switchers 490
Battery pack protection 490
LT1510 battery charger IC 490
LTC1729 Li-Ion charge termination IC 491
Complete 2-cell Li-Ion charger 491
The charge cycle 491
Board layout and testing 491
213 A miniature, low dropout battery charger for lithium-ion batteries 492
Introduction 492
Operation and circuit description 492
Programming charge current 493
Typical application 493
1.5A single cell battery charger 493
Conclusion 493
214 New charger topology maximizes battery charging speed 494
Introduction 494
LT1511 battery charger IC 494
All surface mount lithium-ion charger 495
215 Inexpensive circuit charges lithium-ion cells 496
Introduction 496
Circuit description 496
Other charging options 497
216 Battery backup regulator is glitch-free and low dropout 498
217 Dual PowerPath controller simplifies power management 500
Automatic switchover between battery and AC adapter 500
Power routing circuit for microprocessor controlled dual battery systems 501
218 Low dropout, constant-current/constant-voltage 3A battery charger 502
Introduction 502
Higher duty cycle for the LT1511 battery charger 502
Enhancing dropout voltage 502
219 Fused lead battery charger ICs need no heat sinks 504
220 New micropower, low dropout regulators ease battery supply designs 506
221 Micropower DC/DC converter with independent low-battery detector 508
A 2-cell to 5V converter 508
Super Burst Mode operation: 5V/80mA DC/DC with 15µA quiescent current 509
222 High efficiency lithium-ion battery charger 510
Lithium-ion battery charger 510
Thermal calculations 511
223 A 4-cell NiCd regulator/charger for notebook computers 512
Quick charge battery charger 513
Extremely low voltage drop regulator 513
Very low power dissipation 513
Cost-effective and efficient power system 513
224 Switching regulator allows alkalines to replace NiCds 514
Section 13 : Energy Harvesting & Solar Power Circuits
225 Tiny 2-cell solar panel charges batteries in compact, off-grid devices 518
Introduction 518
The importance of maximum power point control 518
LTC3105 boost converter with input power control 518
Solar-powered Li-Ion battery charger 519
Conclusion 519
226 Energy harvester produces power from local environment, eliminating batteries in wireless sensors 520
Introduction 520
Ambient energy sources 520
Application examples 521
Piezoelectric transducer application 521
Seebeck transducer application 521
Harvest energy from the EM field produced by standard fluorescent lights 521
Conclusions 521
Section 14 : Charge Pump DC/DC Converter Design 522
227 Step-down charge pumps are tiny, efficient and very low noise 524
Introduction 524
Efficient low noise fixed 1.5V output charge pump with ultrasmall footprint 524
Ultralow noise adjustable charge pump with spread spectrum operation 525
Versatility 525
Conclusion 525
228 New charge pumps offer low input and output noise 526
Burst Mode operation vs constant frequency 526
Input noise reduction 527
Typical applications 527
229 Step-up/step-down DC/DC conversion without inductors 528
Introduction 528
Regulator operation 528
Dual output supply from a 2.7V to 10V input 529
Conclusion 529
230 Ultralow quiescent current DC/DC converters for light load applications 530
2-cell to 5V conversion with IQ.=.12µA 530
Ultralow quiescent current (IQ.< .5µA) regulated supply
Micropower LDO regulator consumes < 5µA
Section 15 : Flyback Converter Design 532
231 Micropower isolated flyback converter with input voltage range from 6V to 100V 534
Introduction 534
Simple and accurate primary-side voltage sensing 534
Very small size, low component count solution 534
Low IQ, small preload and high efficiency 535
Conclusion 535
232 Flyback controller simplifies design of low input voltage DC/DC converters 536
Introduction 536
High efficiency controller capabilities 536
3.3V, 10A converter operates from a 9V to 18V source 536
3.3V, 10A converter operates from a 9V to 36V source 537
Conclusion 537
233 Flyback controller improves cross regulation for multiple output applications 538
Introduction 538
Improved load and cross regulation 539
Efficiency 539
Composite feedback provides additional design flexibility 539
Conclusion 539
234 No RSENSE controller is small and efficient in boost, flyback and SEPIC applications 540
Introduction 540
A high efficiency 5V, 2A networking logic supply 540
A 2 square inch, 12V non-isolated flyback housekeeping supply for telecom applications 541
Programmable undervoltage lockout provides clean start-up and power-down 541
235 Isolated flyback converter regulates without an optocoupler 542
Introduction 542
The design criteria 542
Circuit description 542
Circuit operation 543
Conclusion 543
236 Isolated DC/DC conversion 544
237 Isolated power supplies for Local Area Networks 546
Introduction 546
Circuit design 546
Transformer design 547
238 A battery-powered laptop computer power supply 548
Section 16 : Supercapacitor Charging 550
239 Supercapacitor-based power backup system protects volatile data in handhelds when power is lost 552
Introduction 552
Backup power application 552
Conclusion 553
240 Supercapacitor-based power backup prevents data loss in RAID systems 554
Introduction 554
Backup power applications 554
Design example 555
Conclusion 555
241 Complete energy utilization improves run time of a supercap ride-through application by 40% 556
Introduction 556
Complete energy utilization maximizes run time of supercap ride-through application 556
40% improvement in run time 557
How it works 557
Maximizing usage of the energy in the supercap 557
Conclusion 557
242 Supercapacitors can replace a backup battery for power ride-through applications 558
Introduction 558
Supercapacitor characteristics 558
Conclusion 559
Section 17 : Current Source Design 560
243 Convert temperature to current at high linearity with current source 562
Electronics 101 562
A real 2-terminal current source 562
The LT3092 as a T-to-I converter 563
Conclusion 563
244 Versatile current source safely and quickly charges everything from large capacitors to batteries 564
Introduction 564
Safe, small and flexible 564
Simple strobe capacitor charger 564
Charge small capacitors fast 565
Charge batteries too 565
Conclusion 565
Section 18 : Hot Swap and Circuit Protection 566
245 Protect sensitive circuits from overvoltage and reverse supply connections 568
Introduction 568
Undervoltage, overvoltage and reverse supply protection 568
Accurate and fast overvoltage and undervoltage protection 569
Novel reverse supply protection 569
There’s more! AC blocking, reverse VIN Hot Swap control when VOUT is powered 569
Conclusion 569
246 Simple energy-tripped circuit breaker with automatic delayed retry 570
Introduction 570
Higher currents permitted for shorter time intervals 570
A current-controlled delay interval 571
Extending the retry time interval 571
Conclusion 571
247 Hot Swap controller, MOSFET and sense resistor are integrated in a 5mm.×.3mm DFN for accurate current limit and load current monitoring in tight spaces 572
Introduction 572
LTC4217 features 572
Integrated MOSFET and sense resistor 573
Adjustable current limit 573
Voltage and current monitoring 573
Typical application 573
248 Hot Swap solution meets AMC and MicroTCA standards 574
Introduction 574
Advanced mezzanine card application 575
Conclusion 575
249 An easy way to add auxiliary control functions to hot swap cards 576
Introduction 576
Additional control 576
Conclusion 577
250 Electronic circuit breaker in small DFN package eliminates sense resistor 578
Introduction 578
Overcurrent protection 578
Flexible overcurrent setting 578
Overvoltage protection 578
Typical electronic circuit breaker (ECB) application 578
Accurate ECB with sense resistor 579
High side switch for N-channel logic level MOSFET 579
Conclusion 579
251 AdvancedTCA Hot swap controller monitors power distribution 580
Introduction 580
Circuit solutions 580
Cutting diode dissipation 580
Zero Volt Transient 580
252 Protecting and monitoring hot swappable cards in high availability systems 582
Introduction 582
Redundant power 582
Monitoring power through a Hot Swap controller 582
Adding fuse detection 583
Summary 583
253 AdvancedTCA Hot Swap controller eases power distribution 584
Introduction 584
Power requirements 584
Circuit solutions 584
Zero Volt Transient 585
Energy storage 585
Computing energy 585
254 PCI Express power and MiniCard solutions 586
Introduction 586
Power requirements 586
Circuit solutions 587
PCI express Mini Card 587
255 Low voltage hot swap controller ignores backplane noise and surges 588
Control 25W with a 10-lead MS package 588
Dual level current control 588
Inrush limiting 589
Adaptive response to overloads 589
Recovery from faults 589
256 Hot Swap circuit meets InfiniBand specification 590
257 Hot Swap and buffer I2C buses 592
Capacitance buffering and rise time accelerator features 593
Conclusion 593
258 Power supply isolation controller simplifies hot swapping the CompactPCI bus for 5V-/3.3V-only applications 594
LTC1646 feature summary 594
Typical application 595
Power-up sequence 595
Conclusion 595
259 A 24V/48V hot swap controller 596
Typical application 596
Automatic restart 597
260 Dual channel Hot Swap controller/power sequencer allows insertion into a live backplane 598
Basic operation 598
Power supply tracking and sequencing 599
Conclusion 599
261 Hot swapping the compactPCI bus 600
LTC1643 feature summary 600
Typical application 601
Power-up sequence 601
Conclusion 601
262 Power solutions for the device bay 602
Device bay power requirements 602
Power solution for Vid_3.3V on the system side 603
Power solutions for DB32, DB20 and DB13 form factors on the device side 603
263 Hot swapping the PCI bus 604
Inrush current and data bus problems 605
Hot swappable PCI slot using the LTC1421 605
System timing 605
Conclusion 605
264 Safe hot swapping 606
Typical application 606
Board insertion timing 607
Section 19 : Power over Ethernet 608
265 Active bridge rectifiers reduce heat dissipation within PoE security cameras 610
Introduction 610
The old way loses power 610
Improve performance with ideal diodes 611
Results 611
Conclusion 611
266 High power PoE PD interface with integrated flyback controller 612
Introduction 612
PD interface controller 612
Synchronous flyback controller 613
High efficiency, triple output, high power PD 613
PSE and auxiliary supplies 613
2-pair vs 4-pair PD 613
Conclusion 613
267 Simple battery circuit extends Power over Ethernet (PoE) peak current 614
Introduction 614
The PoE circuit 615
PowerPath and charger circuit 615
High transient load or continuous current load operation 615
Optimization options 615
Conclusion 615
268 Fully autonomous IEEE 802.3af power over ethernet midspan PSE requires no microcontroller 616
Introduction 616
A PSE’s duties 616
Disconnect detection 617
Supplying 3.3V from -48V 617
LTC4259A options 617
269 Power over Ethernet isolated power supply delivers 11.5W at 90% efficiency 618
Conclusion 619
Section 20 : System Monitoring and Control 620
270 Pushbutton on/off controller with failsafe voltage monitoring 622
Introduction 622
Pushbutton challenges 622
Orderly power-on 623
Orderly power-off: short interrupt pulse 623
Failsafe features 623
Conclusion 623
271 Versatile voltage monitors simplify detection of overvoltage and undervoltage faults 624
Introduction 624
Basic operation 624
Minimum fault length monitor 625
Conclusion 625
272 Power supply sequencing made simple 626
Introduction 626
Three phases of the power management cycle 626
LTC2928 configuration software designs it for you 627
Conclusion 627
273 Pushbutton on/off controller simplifies system design 628
Introduction 628
De-bounces turn-on 628
Protect against faults at power-up 628
Controlled power-down 629
Operation without µP 629
High voltage, micropower 629
Conclusion 629
274 Tracking and sequencing made simple with tiny point-of-load circuit 630
Introduction 630
Basic operation 630
Negative supply tracking 631
Conclusion 631
275 Accurate power supply sequencing prevents system damage 632
Introduction 632
How it works 632
Conclusion 633
276 Power supply tracker can also margin supplies 634
Conclusion 635
277 Dual micropower comparator with integrated 400mV reference simplifies monitor and control functions 636
Introduction 636
“Gas gauge” battery monitor 636
Simple window-function status monitor 637
Micropower thermostat/temperature alarm 637
Conclusion 637
278 Monitor network compliant -48V power supplies 638
Introduction 638
Features 638
Application example 639
279 Multiple power supplies track during power-up 640
Introduction 640
Five supply voltage tracker circuit 640
Conclusion 641
280 I2C fan control ensures continuous system cooling 642
Introduction 642
Continuous system cooling and tachometer monitoring 643
Additional features 643
281 Monitor system temperature and multiple supply voltages and currents 644
Multitude of measurements 645
Section 21 : Powering LED Lighting & Other Illumination Devices
282 60V, synchronous step-down high current LED driver 648
Introduction 648
48V input to 35V output, 10A LED driver optimized for efficiency 648
36V input to 20V output, 10A LED driver with fastest PWM dimming 649
Solar-powered battery charger 649
Conclusion 649
283 60V buck-boost controller drives high power LEDs, charges batteries and regulates voltage with up to 98.5% efficiency at 100W and higher 650
Introduction 650
Buck-boost controller drives 100W LED string for airplane and truck lights 650
36V, 2.5A SLA battery charger 650
120W, 6V to 55V voltage regulator 651
Conclusion 651
284 Offline LED lighting simplified: high power factor, isolated LED driver needs no opto-isolators and is TRIAC dimmer compatible 652
Introduction 652
No-opto operation 652
High power factor, low harmonics 653
TRIAC dimmer compatible 653
Open- and shorted-LED protection 653
CTRL pins and analog dimming 653
Conclusion 653
285 Reduce the cost and complexity of medium LCD LED backlights with a single inductor LED driver for 60.LEDs 654
Introduction 654
Typical application 654
Need more current? 654
TSET pin for thermal protection 655
Channel disable capability 655
Conclusion 655
286 100V controller drives high power LED strings from just about any input 656
Introduction 656
Boost 657
Buck mode 657
Buck-boost mode 657
Conclusion 657
287 Triple LED driver in 4mm.×.5mm QFN supports LCD backlights in buck, boost or buck-boost modes and delivers 3000:1 PWM dimming ratio 658
Introduction 658
Integrated PMOS drivers improve PWM dimming ratio to 3000:1 658
Buck mode circuit drives three 500mA LED strings 659
Boost mode circuit drives three 200mA LED strings 659
Buck-boost mode circuit survives load dump events 659
Conclusion 659
288 µModule LED driver integrates all circuitry, including the inductor, in a surface mount package 660
Introduction 660
A superior LED driver 660
Easy to use 660
Rich feature set 660
Conclusion 661
289 Versatile TFT LCD bias supply and white LED driver in a 4mm.×.4mm QFN 662
Introduction 662
3-output TFT supply with digitally dimmed LED backlight 663
Conclusion 663
290 Tiny universal LED driver can gradate, blink or turn on nine individual LEDs with minimal external control 664
Introduction 664
Blinking and gradation modes 664
Single IC drives cell phone backlight, new message/missed call/battery charger indicator, and RGB function select button 664
Control for cell phone backlight, vibrator motor and sound 665
Conclusion 665
291 Drive large TFT-LCD displays with a space-saving triple-output regulator 666
Introduction 666
Conclusion 667
292 Versatile high power LED driver controller simplifies design 668
Introduction 668
Fully integrated, high power LED driver controller 668
LED dimming 669
Boost circuit 669
Buck-boost circuit 669
LED protection and other features 669
Conclusion 669
293 High voltage buck converters drive high power LEDs 670
Introduction 670
Single buck 1A LED driver 670
Dual buck 1.5A LED driver 671
Conclusion 671
294 Wide input range 1A LED driver powers high brightness LEDs with automotive and 12VAC supplies 672
Introduction 672
Automotive LED driver 672
Driving LEDs from 12VAC input 672
Thermal regulation 673
Conclusion 673
295 Monolithic converter drives high power LEDs 674
Introduction 674
Boost driver 674
Buck driver 675
Buck-boost driver 675
Conclusion 675
296 Quad output switching converter provides power for large TFT LCD panels 676
Introduction 676
4-output supply with soft-start 677
Wide input range supply 677
Conclusion 677
297 Basic flashlamp illumination circuitry for cellular telephones/cameras 678
Introduction 678
Flashlamp circuitry 678
Conclusion 679
298 DC/DC converter drives white LEDs from a variety of power sources 680
Introduction 680
Lithium-ion source (3.3V to 4.2V) 680
2-alkaline cell source (1.8V to 3.0V) 681
Automotive power source (9V to 16V) 681
Conclusion 681
299 High efficiency ThinSOT white LED driver features internal switch and schottky diode 682
Introduction 682
Li-Ion-powered driver for four white LEDs 682
Dimming control 683
Conclusion 683
300 White LED driver in tiny SC70 package delivers high efficiency and uniform LED brightness 684
Introduction 684
Li-Ion-powered driver for three white LEDs 684
Easy dimming control 685
Conclusion 685
301 Photoflash capacitor charger has fast efficient charging and low battery drain 686
Introduction 686
Features 686
Interfacing to a microcontroller 687
Conclusion 687
302 High efficiency white LED driver guarantees matching LED brightness 688
Introduction 688
Li-Ion LED driver for four white LEDs 688
Dimming control 689
Conclusion 689
303 High power desktop LCD backlight controller supports wide dimming ratios while maximizing lamp lifetime 690
Introduction 690
LT1768 dual CCFL backlight inverter 690
Multimode dimming 691
LT1768 fault modes 691
Additional features 691
304 Tiny regulators drive white LED backlights 692
Introduction 692
Circuit descriptions 692
Brightness control 693
Summary 693
305 High power CCFL backlight inverter for desktop LCD displays 694
306 Low input voltage CCFL power supply 696
307 A precision wideband current probe for LCD backlight measurement 698
Current probe circuitry 698
Current calibrator 699
308 Floating CCFL with dual polarity contrast 700
Section 22 : Automotive and Industrial Power Design 702
309 Versatile industrial power supply takes high voltage input and yields from eight 1A to two 4A outputs 704
Introduction 704
Configurable maximum output current 704
External VCC LDO and external input power supply start-up control 704
Unique power control and features 705
Conclusion 705
310 65V, 500mA step-down converter fits easily into automotive and industrial applications 706
Introduction 706
65V input, 500mA DC/DC converter with an adjustable output down to 800mV 706
24V regulator with 300mA output current limit and input undervoltage lockout 707
Input current limit 707
Conclusion 707
311 2-phase, dual output synchronous boost converter solves thermal problems in harsh environments 708
Introduction 708
Advantages of synchronous rectification 708
Dual output automotive boost converter 708
Conclusion 709
312 High efficiency USB power management system safely charges Li-Ion/polymer batteries from automotive supplies 710
Introduction 710
Complete USB/battery charging solution for use in large transient environments 710
Overvoltage protection covers the entire battery charger/power manager system 711
Conclusion 711
313 Low profile synchronous, 2-phase boost converter produces 200W with 98% efficiency 712
Introduction 712
A 24V output boost converter at 8.5A (continuous), 10.5A (peak) from a car battery 712
Performance results 713
Basic calculations and component selection 713
Conclusion 713
314 4-phase boost converter delivers 384W with no heat sink 714
Introduction 714
384W boost converter 715
Conclusion 715
315 Power monitor for automotive and telecom applications includes ADC and I2C interface 716
Introduction 716
Automotive power monitoring 716
Telecom power monitoring with PoE 716
Conclusion 717
316 Direct efficient DC/DC conversion of 100V inputs for telecom/automotive supplies 718
Introduction 718
Feature-rich controller 718
High efficiency 36V–72V to 2.5V/6A power supply 719
317 Monolithic step-down regulator withstands the rigors of automotive environments and consumes only 100µA of quiescent current 720
Introduction 720
Features of the LT3437 720
Brutal input transients 720
Low quiescent currents 721
Soft-start capability 721
Conclusion 721
318 Monitor and protect automotive systems with integrated current sensing 722
Introduction 722
Simple current monitoring solutions 722
Solving the H-bridge problem 723
Conclusion 723
Section 23 : Video Design Solutions 724
319 High resolution video solutions using single 5V power 726
Introduction 726
High resolution video input-port multiplexer 727
High resolution single-supply cable driver 727
Economical SXGA/HD cable driver 727
Conclusion 727
320 Pass HDMI compliance tests with ease 728
Introduction 728
LTC4300A-1 bus buffer 728
LTC4300A-3 level shifting buffer 729
Conclusion 729
321 Video difference amplifier brings versatility to low voltage applications 730
Introduction 730
Dual input pair zaps common mode noise pickup 730
Perform video rate analog arithmetic 731
Conclusions 731
322 Video signal distribution using low supply voltage amplifiers 732
Introduction 732
Video signal characteristics 732
Amplifier considerations 733
Handling AC-coupled video signals 733
Conclusion 733
323 Tiny RGB video multiplexer switches pixels at 100MHz 734
Introduction 734
Expanding inputs does not increase power dissipation 734
Add your own logo 735
324 An adjustable video cable equalizer 736
325 4.×.4 video crosspoint has 100MHz bandwidth and 85dB rejection at 10MHz 738
4.×.4 crosspoint 738
326 Single 4-input IC gives over 90dB crosstalk rejection at 10MHz and is expandable 740
Introduction 740
Expanding the number of inputs 740
PC board layouts 741
Switching transients 741
327 Send color video 1000 feet over low cost twisted-pair 742
328 Video circuits collection 744
Introduction 744
Multiplex amplifiers 744
Loop through cable receivers 745
DC restore circuits 745
Fader circuits 745
329 Low cost differential input video amplifiers simplify designs and improve performance 746
Wideband voltage controlled amplifier 746
Extending the input range on the LT1193 747
PART 2 : Mixed Signal 748
Section 1 : Data Conversion: Analog-to-Digital 750
330 Generating a ±10.24V true bipolar input for an 18-bit, 1Msps SAR ADC 752
Introduction 752
Simple driver circuit 752
Layout is important 753
Conclusion 753
331 Driving a low noise, low distortion 18-bit, 1.6Msps ADC 754
Introduction 754
Fully differential driver 754
Single supply driver 755
Layout considerations 755
Conclusion 755
332 Driving lessons for a low noise, low distortion, 16-bit, 1Msps SAR ADC 756
Introduction 756
Single-ended to differential converter 756
Fully differential drive 756
PCB layout 756
Conclusion 757
333 Maximize the performance of 16-bit, 105Msps ADC with careful IF signal chain design 758
Introduction 758
Signal chain topology 758
Conclusion 759
334 Upgrade your microcontroller ADC to true 12-bit performance 760
Introduction 760
Application circuits 760
Conclusion 761
335 Digitize a $1000 sensor with a $1 analog-to-digital converter 762
Introduction 762
Digitize an accurate sensor with an accurate ADC 762
Not so obvious features 762
Conclusion 763
336 True rail-to-rail, high input impedance ADC simplifies precision measurements 764
Introduction 764
Solving common issues 764
Applications 765
Conclusion 765
337 Easy Drive ADCs simplify measurement of high impedance sensors 766
338 Easy Drive delta-sigma analog-to-digital converters cancel input current errors 768
Introduction 768
How does it work? 768
What is wrong with on-chip buffers? 769
Conclusion 769
339 16-bit ADC simplifies current measurements 770
Introduction 770
Data transfer 770
Data reception pseudocode 771
Power and analog inputs 771
Conclusion 771
340 12-bit ADC with sequencer simplifies multiple-input applications 772
New ADC automatically converts multiple inputs with different spans at different rates 772
Writing and reading the sequencer 772
Running the sequencer 773
Conclusion 773
341 A-to-D converter does frequency translation 774
Down conversion with an ADC 774
342 Resolving very small temperature differences with a delta-sigma ADC 776
Platinum RTDs 776
Self-heating effects 776
Bridge connection of RTDs 777
Series connection of RTDs 777
Pulsed excitation 777
343 1- and 2-channel No Latency .S 24-bit ADCs easily digitize a variety of sensors, part 1 778
Single-ended half-bridge digitizer with reference and ground sensing 778
Pseudo-differential applications 779
Noise rejection 779
344 1- and 2-channel No Latency .S 24-bit ADCs easily digitize a variety of sensors, part 2 780
Introduction 780
Digital cold junction compensation 780
RTD temperature digitizer 781
Conclusion 781
345 24-bit ADC measures from DC to daylight 782
346 High accuracy differential to single-ended converter for ±5V supplies 784
Introduction 784
Operation 784
347 Micropower MSOP 10-bit ADC samples at 500ksps 786
Introduction 786
Features 786
Smallest size (MSOP) 786
3V or 5V supplies 786
Performance 786
Micropower performance with auto shutdown at full speed 786
High speed capability 787
Good DC and AC specs 787
Flexible inputs 787
Serial I/O 787
Battery current monitor 787
Conclusion 787
348 16mW, serial/parallel 14-bit ADC samples at 200ksps 788
Introduction 788
High performance without high power 788
Differential inputs with wideband CMRR 789
Single supply or dual supply operation 789
On-chip reference 789
Parallel or serial data output 789
Perfect for telecom: wide dynamic range 789
Conclusions 789
349 16-bit, 333ksps ADC achieves 90dB SINAD, -100dB THD and no missing codes 790
Fastest 16-bit sampling ADC 790
Outstanding DC and AC performance 790
Differential inputs reject common mode noise 791
Applications 791
350 16-bit, 100ksps A/D converter runs on 5V supply 792
Product features 792
Circuit description 792
AC and DC performance 792
Applications 793
Conclusion 793
351 14-bit, 800ksps ADC upgrades 12-bit systems with 81.5dB SINAD, 95dB SFDR 794
Higher dynamic range ADCs 794
LTC1419 features 794
The LTC1410’s big brother 794
10dB extra dynamic range for signal applications 795
Noise rejecting differential inputs 795
Other nice features 795
Time to upgrade? 795
352 Micropower 4- and 8-channel, 12-bit ADCs save power and space 796
Introduction 796
Micropower ADCs in small packages 796
Conserve power with auto shutdown operation 796
Good DC performance 797
Versatile, flexible serial I/O 797
Latchup proof MUX inputs 797
Individual ADC and MUX chip selects enhance flexibility 797
MUXOUT/ADCIN economizes signal conditioning 797
Conclusion 797
353 1.25Msps, 12-bit ADC conserves power and signal integrity on a single 5V supply 798
Introduction 798
Single 5V supply, high speed, lowest power 798
Tiny package 798
Complete ADC with reference and wideband S/H 798
Benefits 799
Reduce power with single supply operation and two power saving shutdown modes 799
Wide bandwidth CMRR 799
No latency and low bit error rate (BER) 799
DSP interface 799
Exemplary AC and DC performance 799
354 Micropower ADC and DAC in SO-8 give PCs a 12-bit analog interface 800
Introduction 800
Small, micropower ADC and DAC 800
PC 2-channel analog I/O interface 800
Conclusion 801
Anchor 18 801
355 Micropower 12-bit ADCs shrink board space 802
Introduction 802
Micropower and 12-bits in an SO-8 package 802
Resistive touchscreen interface 803
356 1.25Msps 12-bit A/D converter cuts power dissipation and size 804
Introduction 804
High accuracy conversions: AC or DC 804
Important multiplexed applications 804
Ideal for telecommunications 804
Differential inputs reject noise 805
Low power applications 805
Conclusion 805
357 500ksps and 600ksps ADCs match needs of high speed applications 806
Introduction 806
High speed ADC family members 806
Important applications 807
Conclusion 807
358 5V and 3V, 12-bit ADCs sample at 300kHz on 75mW and 140kHz on 12mW 808
Complete ADCs provide lowest power and highest speed on single or dual supplies 808
5V ADCs sample at 300kHz on 75mW of power 808
Even more power savings: 3V ADC samples at 140kHz on 12mW 809
Conclusion 809
Micropower, SO-8, 8-bit ADCs sample at 1kHz on 3µA of supply current 810
Two micropower ADCs 810
Longer battery life 810
A/D conversion for 3V systems 811
Smaller instrument size 811
AC and DC performance 811
Conclusion 811
Section 2 : Data Conversion: Digital-to-Analog 812
360 12-bit DAC in TSOT-23 includes bidirectional REF pin for connection to op amp or external high precision reference 814
Introduction 814
Applications using REF pin 814
Conclusion 815
361 Highly integrated quad 16-bit, SoftSpan, voltage output DAC for industrial and control applications 816
Introduction 816
Unprecedented integration 816
Ease of use 816
Example circuits 816
Conclusion 816
362 Multiple output range 16-bit DAC design made simple 818
Introduction 818
The old way 819
The new, easy way 819
Conclusion 819
363 Selecting op amps for precision 16-bit DACs 820
364 Applications versatility of dual 12-bit DAC 822
Introduction 822
Applications 822
Digitally controlled attenuator and PGA 822
Amplified attenuator and attenuated PGA 822
365 First dual 12-bit DACs in SO-8 824
Low power 5V or 3V single supply 824
Complete standalone performance 824
Rail-to-rail outputs 825
A wide range of applications 825
Conclusion 825
366 3V and 5V 12-bit rail-to-rail micropower DACs combine flexibility and performance 826
Low power, 5V or 3V single supply operation 826
Flexibility with standalone performance 826
4-quadrant multiplying DAC application 826
367 12-bit rail-to-rail micropower dacs in an SO-8 828
5V and 3V operation 828
True rail-to-rail output 828
Wide range of applications 829
Flexibility, true rail-to-rail performance and micropower all in a tiny SO-8
Section 3 : Data Acquisition 830
368 16-channel, 24-bit .S ADC provides small, flexible and accurate solutions for data acquisition 832
Introduction 832
Noise reduction 833
Conclusion 833
369 A versatile 8-channel multiplexer 834
Introduction 834
Low power, daisy-chain serial interface, 8-channel A./D system 835
Conclusion 835
370 Temperature and voltage measurement in a single chip 836
Introduction 836
Measurement performance 836
Typical application 837
Conclusion 837
371 Applications for a micropower, low charge injection analog switch 838
Micropower V-F converter 838
Precision voltage doubler 839
Quad 12-bit sample and hold 839
372 12-bit 8-channel data acquisition system interfaces to IBM PC serial port 840
IBM PCs collect analog data 840
Two glue chips provide the interface 840
A few lines of BASIC read the data 841
Summary 841
373 Auto-zeroing A/D offset voltage 842
Introduction 842
Circuit description 842
374 Complex data acquisition system uses few components 844
Introduction 844
Implementation 844
Filter design specifications and test results 844
System considerations 844
Conclusion 845
375 A two wire isolated and powered 10-bit data acquisition system 846
Introduction 846
Circuit description 846
Summary 847
376 Closed loop control with data acquisition systems 848
Introduction 848
Circuit description 848
Summary 849
377 Electrically isolating data acquisition systems 850
Introduction 850
Circuit description 850
Alternatives 850
Summary 851
378 Temperature measurement using data acquisition systems 852
Introduction 852
Thermocouple systems 852
Thermilinear networks 853
Thermistors 853
Silicon sensors 853
379 Sampling of signals for digital filtering and gated measurements 854
Introduction 854
The LTC1090 sample and hold 854
8-channel data acquisition system with digital filter 855
4th order elliptic filter 855
Gated measurements of fast signals 855
380 Data acquisition systems communicate with microprocessors over four wires 856
The LTC1090 family 856
Advantages of serial communications 856
Speed is usually limited by the MPU 857
Talking to serial port MPUs 857
Talking to MPUs without serial ports 857
Sharing the serial interface 857
Conclusion 857
References 857
Section 4 : Communications Interface Design 858
381 Addressable I2C bus buffer provides capacitance buffering, live insertion and nested addressing in 2-wire bus systems 860
Introduction 860
Live insertion and removal and capacitance buffering application 860
Nested addressing and 5V to 3.3V level translator application 861
382 Single interface chip controls two smart cards 862
Introduction 862
Features 863
Ease of use 863
Conclusion 863
383 Isolated RS485 transceiver breaks ground loops 864
384 RS485 transceivers sustain ±60V faults 866
Introduction 866
Up to ±60V faults 866
128-node networks at 250kBd 867
Extending protection beyond ±60V 867
385 SMBus accelerator improves data integrity 868
Introduction 868
The solution 869
Making the upgrade 869
386 Providing power for the IEEE1394 “FireWire” 870
387 5V RS232/RS485 multiprotocol transceiver 872
Introduction 872
RS232 and RS485 interfaces 872
Key features 872
Conclusion 873
388 10Mbps multiple protocol serial chip set: Net1 and Net2 compliance by design 874
Introduction 874
Review of interface standards 874
Typical application 874
389 RS485 transceivers operate at 52Mbps over 100 feet of unshielded twisted pair 876
High speed differential SCSI (fast-20/fast-40 HVD) 876
Transmission over long distances 876
1Mbps over 12,000 feet using repeaters 877
1.6Mbps over 8000 feet using repeaters 877
Conclusion 877
390 The “smart rock”: a micropower transponder 878
Introduction 878
The micropower subcircuits 878
The oscillator 878
If amplifier 878
Power driver 878
The smart rock system 879
Receiver 879
Transmitter 879
Blanking 879
Conclusion 879
391 Power supplies for subscriber line interface circuits 880
Circuit descriptions 880
LT1171 supplies -23.8V at 50mA and -71.5V at 60mA 880
LT1269 supplies -23.5V at 60mA and -71.5V at 120mA from 5V input 880
Layout and thermal considerations 881
Bill of materials 881
392 Precision receiver delay improves data transmission 882
Circuit description 882
Additional features 883
Applications 883
393 RS485 transceivers reduce power and EMI 884
LTC1481 884
LTC1483 885
LTC1487 885
Conclusions 885
394 Interfacing to V.35 networks 886
What is V.35? 886
Problems with traditional implementations 886
LTC1345 887
Complete V.35 port 887
395 ESD testing for RS232 interface circuits 888
ESD transients during powered operation 888
396 RS232 interface circuits for 3.3V systems 890
VPP switcher drives 3V RS232 891
ESD protection 891
397 RS232 transceivers for handheld computers withstand 10kV ESD 892
Interfacing with 3V logic 892
ESD protection techniques 892
PC board layout 893
Conclusion 893
398 Low power CMOS RS485 transceiver 894
Introduction 894
Proprietary output stage 894
Propagation delay 895
LTC485 line length vs data rate 895
399 Active termination for SCSI-2 bus 896
Overview of SCSI-2 896
Shortcomings of passive terminators 897
Active terminators 897
400 RS232 transceiver with automatic power shutdown control 898
401 A single supply RS232 interface for bipolar A to D converters 900
402 Design considerations for RS232 interfaces 902
Introduction 902
Power supply generators 902
Load driving 902
Fault conditions 903
Isolated transceiver 903
403 New 12-bit data acquisition systems communicate with microprocessors over four wires 904
The LTC1290 family 904
Speed is usually limited by the MPU 905
Talking to serial port MPUs 905
Talking to MPUs without serial ports 905
Sharing the serial interface 905
Conclusions 905
References 905
404 Extending the applications of 5V powered RS232 transceivers 906
High speed operation 906
Power supply tricks 906
Operation with +5V and +12V supplies 907
405 New developments in RS232 interfaces 908
Section 5 : Instrumentation Design 910
406 System monitor with instrumentation-grade accuracy used to measure relative humidity 912
A psychrometer: not nearlyas ominous as it sounds 912
Error budget 913
Try it out! 913
407 6-channel SAR ADCs for industrial monitoring and portable instruments 914
Power line monitoring application 914
Conclusion 915
408 Instrumentation amplifiers maximize output swing on low voltage supplies 916
Introduction 916
A clearer picture of the problem 916
The solutions 917
The LTC6800 solution 917
409 Ultraprecise instrumentation amplifier makes robust thermocouple interface 918
Introduction 918
The requirements of thermocouple amplification 918
A battery-powered thermocouple amplifier 918
Filtering and protection 919
410 16-bit SO-8 DAC has 1LSB (max) INL and DNL over industrial temperature range 920
Nice features of the 16-bit DACs 920
16-bit accuracy over temperature without autocalibration 920
Ultralow 1nV-s glitch 921
Precision 0V to10V outputs with one op amp 921
Precision ±10V outputs with a dual op amp 921
411 Gain trimming in instrumentation amplifier-based systems 922
412 Signal conditioning for platinum temperature transducers 924
413 Designing with a new family of instrumental amplifiers 926
PART 3 : Signal Conditioning 928
Section 1 : Operational Amplifier Design Techniques 930
414 High voltage CMOS amplifier enables high impedance sensing with a single IC 932
Introduction 932
The LTC6090 easily solves high voltage sensing problems 932
Accurate 50.00V reference 933
Simple large-signal buffer 933
Conclusion 933
415 Matched resistor networks for precision amplifier applications 934
Introduction 934
Common mode rejection ratio 934
Harmonic distortion 935
Stability 935
Conclusion 935
416 Using a differential I/O amplifier in single-ended applications 936
Introduction 936
Background 936
Simple single-ended connection of a fully differential op amp 936
A single-ended transimpedance amplifier 937
Conclusion 937
417 Single-ended to differential amplifier design tips 938
Introduction 938
Input impedance matching 938
The DC-coupled differential amplifier 938
418 Current sense amp inputs work from -0.3V to 44V independent of supply 940
Introduction 940
Solenoid monitoring 940
Supply monitoring 941
Conclusion 941
419 Tiny amplifiers drive heavy capacitive loads at speed 942
Introduction 942
Demanding circuit requirements 942
Tiny current feedback amplifiers 942
Component selection and testing 943
Conclusion 943
420 Micropower op amps work down to 1.8V total supply, guaranteed over temperature 944
Introduction 944
NiMH and alkaline 944
Supply friendliness 944
Portable gas sensor 945
Conclusion 945
421 Low noise amplifiers for small and large area photodiodes 946
Introduction 946
Small area photodiode amplifiers 946
Large area photodiode amplifiers 946
422 Op amp selection guide for optimum noise performance 948
Introduction 948
Quantifying resistor thermal noise and op amp noise 948
Summing the noise sources 949
Selecting the best op amps 949
Conclusion 949
423 Easy-to-use differential amplifiers simplify balanced signal designs 950
Introduction 950
Easy-to-use circuit topology 950
Common mode range considerations 951
Common mode input range extension 951
Versatile functional block 951
Conclusion 951
424 Dual 25µV micropower op amp fits in 3mm.×.3mm package 952
Introduction 952
Hall sensor amplifier 952
DAC amplifier 953
425 100MHz op amp features low noise rail-to-rail performance while consuming only 2.5mA 954
Low power, , photodiode AC transimpedance amplifier outperforms monolithic solutions 954
Single supply 16-bit ADC driver 955
Conclusion 955
426 High performance op amps deliver precision waveform synthesis 956
Introduction 956
The LT1722, LT1723 and LT1724 low noise amplifiers 956
DAC output amplifier 956
Conclusion 957
427 Power op amp provides on-the-fly adjustable current limit for flexibility and load protection in high current applications 958
Introduction 958
Introducing the LT1970 958
Boosted output current with “snap-back” current limiting 959
Conclusion 959
428 Fast and accurate 80MHz amplifier draws only 2mA 960
Introduction 960
Single supply 1A laser driver 960
Low power amplifier with 250V output swing 961
Conclusion 961
429 SOT-23 superbeta op amp saves board space in precision applications 962
Introduction 962
Applications 962
Getting rail-to-rail operation without rail-to-rail inputs 962
Precision photodiode amplifier 963
Single supply current source for platinum RTD 963
Conclusion 963
430 325MHz low noise rail-to-rail SOT-23 op amp saves board space 964
1MO transimpedance amplifier achieves near theoretical noise performance with large-area photodiodes 964
Conclusion 965
431 Fast op amps operate rail-to-rail on 2.7V 966
Parallel composite amplifier achieves low distortion into heavy loads 966
Rail-to-rail pulse-width modulator using the LT1809 967
432 Rail-to-rail amplifiers operate on 2.7V with 20µV offset 968
Remote 2-wire geophone preamp using the low noise LT1677 968
Difference amplifier using the LT1884: ±42V CM input range on a single 5V supply without sacrificing differential gain 969
433 Single resistor sets the gain of the best instrumentation amplifier 970
Introduction 970
Low input bias current and noise voltage 970
Input protection 970
ADC signal conditioning 971
Current source 971
434 Maximize dynamic range with micropower rail-to-rail op amp 972
Variable current source 972
High side current sense amplifier 972
3.3V, 1kHz, 4th order Butterworth filter 973
Picoampere input current instrumentation amplifier 973
435 1µA op amp permits precision portable circuitry 974
5.5µA, 0.05µV/°C chopped amplifier 974
0.03% linear V/F converter with 13µA power drain 975
Portable reference 975
436 Low power, fast op amps have low distortion 976
Introduction 976
Buffering data acquisition systems 976
Filters 977
A two op amp instrumentation amplifier 977
Conclusion 977
437 Operational amplifier selection guide for optimum noise performance 978
438 Micropower dual and quad JFET op amps feature pA input bias currents and C-Load drive capability 980
Introduction 980
Driving large capacitive loads 980
Applications 980
439 Fast current feedback amplifiers tame low impedance loads 982
Introduction 982
Driving transformer-coupled loads 982
Driving capacitive loads 983
440 C-Load op amps conquer instabilities 984
Introduction 984
Driving ADCs 984
Remaining stable in the face of difficult loads 985
Conclusion 985
441 Applications of a rail-to-rail amplifier 986
Precision low dropout regulator 986
Single supply, 1kHz, 4th order Butterworth filter 987
Buffering A/D converters 987
442 Source resistance-induced distortion in op amps 988
Introduction 988
Test circuit 988
Results 989
443 C-Load op amps tame instabilities 990
Introduction 990
The problem 990
An example 990
The solution 991
Conclusions 991
444 A broadband random noise generator 992
445 Peak detectors gain in speed and performance 994
Introduction 994
Detecting sine waves 994
Detecting pulses 995
446 3V operation of linear technology op amps 996
447 High frequency amplifier evaluation board 998
Introduction 998
High speed layout techniques 998
Optional components 998
Supply bypass capacitors 998
448 Current feedback amplifier “dos and don’ts” 1000
Introduction 1000
449 Improved JFET op amp macromodel slews asymmetrically 1002
References 1003
450 Chopper vs bipolar op amps—an unbiased comparison 1004
451 Ultralow noise op amp combines chopper and bipolar op amps 1006
Noise measurements 1007
452 A SPICE op amp macromodel 1008
Introduction 1008
The LT1012 1008
The LT1012 macromodel 1008
Obtaining this macromodel 1009
References 1009
453 A single amplifier, precision high voltage instrument amp 1010
Reference 1011
454 Micropower, single supply applications: (1) a self-biased, buffered reference (2) megaohm input impedance difference amplifier 1012
A self-biased, buffered reference 1012
Megaohm input impedance difference amplifier 1013
Reference 1013
455 Noise calculations1 in op amp circuits 1014
Instructions for operating NOISE 1015
456 An op amp SPICE macromodel 1016
457 Operational amplifier selection guide for optimum noise performance 1018
Section 2 : Special Function Amplifier Design 1020
458 Ultraprecise current sense amplifier dramatically enhances efficiency and dynamic range 1022
Introduction 1022
Precision buys efficiency 1022
Print your own sense resistors 1023
Design tips and details 1023
Conclusion 1023
459 Dual current sense amplifiers simplify H-bridge load monitoring 1024
Introduction 1024
Measuring load current in the H-bridge 1024
The simple solution 1025
Conclusion 1025
460 Precise gain without external resistors 1026
Introduction 1026
The resistors: 0.04% worst case 1026
The op amp: precision, micropower 1026
So easy to use 1027
Battery monitor circuit 1027
Conclusion 1027
461 Sense milliamps to kiloamps and digitize to 12 bits 1028
Introduction 1028
Operation with an A./.D converter 1028
Conclusion 1029
462 Op amp, comparator and reference IC provide micropower monitoring capability 1030
Introduction 1030
Pilot light flame detector with low-battery lockout 1030
Tip-acceleration detector for shipping containers 1031
Section 3 : Voltage Reference Design 1032
463 Versatile micropower voltage reference provides resistor programmable output from 0.4V to 18V 1034
Introduction 1034
Easy output voltage programming 1034
Create a virtual ground for unipolar processing of bidirectional signals 1035
Shunt mode operation works like precision zener diode 1035
Conclusion 1035
464 Don’t be fooled by voltage reference long-term drift and hysteresis 1036
Lies about long-term drift 1036
Competitive reference measures 500 times worse than claimed 1036
Hysteresis limits repeatability 1037
Hysteresis—often the “missing” spec 1037
Conclusion 1037
465 Voltage references are smaller and more precise 1038
Introduction 1038
Longer battery life with precision 1038
The small fry 1038
Higher performance, industrial temperature range and surface mount 1039
CMOS DAC with low drift full-scale trimming** 1039
Section 4 : Filter Design 1040
466 A precision active filter block with repeatable performance to 10MHz 1042
Introduction 1042
Device description 1042
Application examples 1043
A 4th order elliptic lowpass filter 1043
A 4th order bandpass filter 1043
Conclusion 1043
467 High frequency active anti-aliasing filters 1044
Introduction 1044
The LT6600-10 lowpass filter 1044
An LT1819-based RC lowpass filter 1044
Anti-aliasing 10MHz filters for a differential 50Msps ADC 1045
Conclusion 1045
468 Design low noise differential circuits using a dual amplifier building block 1046
Introduction 1046
A single-ended to differential amplifier 1046
A differential buffer/driver 1047
A differential to single-ended amplifier 1047
LT1567 free design software 1047
Conclusion 1047
469 A digitally tuned anti-aliasing/reconstruction filter simplifies high performance DSP design 1048
Introduction 1048
Filtering performance and operation 1048
Application example: 2-chip “universal” DSP front end 1049
Conclusion 1049
470 Replace discrete lowpass filters with zero design effort, two item BoM and no surprises 1050
Lowpass filters—the traditional approach 1050
Lowpass filters—the LTC1563 approach 1050
Easy design without sacrificing performance 1051
Also included, Chebyshev filters with gain 1051
Conclusion 1051
471 Free FilterCAD 3.0 software designs filters quickly and easily 1052
Linear phase lowpass filters 1052
Example 1: design a 256kHz linear phase lowpass filter for a single 5V power supply 1052
Example 2: design a 10kHz low power linear phase lowpass filter for a single 3V power supply 1053
Example 3: design a 650kHz linear phase lowpass filter for a single 5V power supply 1053
472 SOT-23 micropower, rail-to-rail op amps operate with inputs above the positive supply 1054
Introduction 1054
Tough general purpose op amps 1054
Tough op amps 1055
Read all of the specs 1055
Over-the-top applications 1055
473 Get 100dB stopband attenuation with universal filter family 1056
474 Tiny 1MHz lowpass filter uses no inductors 1058
Frequency and time-domain response 1058
DC accuracy 1059
Conclusion 1059
475 A family of 8th order monolithic filters in an SO-8 package 1060
LTC1069-1: low power elliptic anti-aliasing filter works from single 3.3V to ±5V supplies 1060
LTC1069-6: 8th order elliptic lowpass works on single 3V, consumes 1mA 1061
LTC1069-7: linear-phase communication filter delivers up to 200kHz cutoff frequency and symmetrical impulse response 1061
Conclusion 1061
476 A 1mV offset, clock-tunable, monolithic 5-pole lowpass filter 1062
Using the filter’s internal oscillator 1062
DC performance 1062
Dynamic range 1063
477 High dynamic range bandpass filters for communications 1064
Introduction 1064
Design 1064
Test results 1064
Conclusions 1065
478 Switched-capacitor lowpass filters for anti-aliasing applications 1066
Introduction 1066
Comparing the LTC1064-1 with RC active filters utilizing operational amplifiers 1066
Performance 1066
Test results 1067
System considerations 1067
Summary 1067
479 Chopper amplifiers complement a DC accurate lowpass filter 1068
480 DC accurate filter eases PLL design 1070
Section 5 : Comparator Design Techniques 1072
481 Rail-to-rail I/O and 2.4V operation allow ultrafast comparators to be used on low voltage supplies 1074
Simultaneous full duplex 75MBd interface with only two wires 1074
1MHz series resonant crystal oscillator with square and sinusoid outputs 1075
482 A seven nanosecond comparator for single supply operation 1076
The LT1394—an overview 1076
4.×.NTSC subcarrier tunable crystal oscillator 1076
High speed adaptive trigger circuit 1077
Comparators feature micropower operation under all conditions 1078
484 Ultralow power comparators include reference 1080
Voltage reference 1080
Undervoltage/overvoltage detector 1081
Single cell lithium-ion battery supply 1081
Section 6 : System Timing Design 1082
485 Using a low power SOT-23 oscillator as a VCO 1084
Introduction 1084
Programming the output frequency 1084
486 SOT-23 1kHz to 30MHz oscillator with single resistor frequency set 1086
Tiny circuit, big performance 1086
Fast start-up time 1087
Two-step design process 1087
Application: temperature-to-frequency converter 1087
Conclusion 1087
Section 7 : RMS to DC Conversion 1088
487 Precision LVDT signal conditioning using direct RMS to DC conversion 1090
Introduction 1090
LVDT operation 1091
Circuit description 1091
Circuit calibration 1091
Conclusion 1091
488 An autoranging true RMS converter 1092
Introduction 1092
Autoranging expands input dynamic range 1093
Circuit description 1093
Conclusion 1093
489 RMS to DC conversion just got easy 1094
Introduction 1094
Ease of use 1094
The trouble with log-antilog 1094
How the LTC1966 RMS to DC converter works 1095
Summary 1095
PART 4 : Wireless, RF & Communications Design
490 High input IP3 mixer enables robust VHF receivers 1098
Introduction 1098
Impedance match design 1099
Conclusion 1099
491 A robust 10MHz reference clock input protection circuit and distributor for RF systems 1100
Introduction 1100
Design requirements 1100
Design implementation 1100
Performance 1101
Conclusion 1101
492 A low power, direct-to-digital IF receiver with variable gain 1102
Introduction 1102
IF receiver performance 1102
Measurement details and receiver circuit 1102
Conclusion 1103
493 Fast time division duplex (TDD) transmission using an upconverting mixer with a high side switch 1104
Introduction 1104
High side VCC switch for a burst mode transmitter using the LT5579 mixer 1104
Conclusion 1105
494 Precision, matched, baseband filter ICs outperform discrete implementations 1106
Introduction 1106
The LTC6601-x lowpass filter 1106
The LTC6605-x, dual, matched, lowpass filter 1107
Conclusion 1107
495 A complete compact APD bias solution for a 10Gbits/s GPON system 1108
Introduction 1108
An APD bias topology with fast current monitor transient response 1108
Conclusion 1109
496 Signal chain noise analysis for RF-to-digital receivers 1110
Introduction 1110
NF to SNR: how much ADC resolution? 1110
SNR to NF 1111
Conclusion 1111
497 Programmable baseband filter for software-defined UHF RFID readers 1112
Introduction 1112
The LTC6602 dual bandpass filter 1112
An adaptable baseband filter for an RFID reader 1112
Conclusion 1113
References 1113
498 High linearity components simplify direct conversion receiver designs 1114
Introduction 1114
The right components for the job 1114
A basic receiver design 1115
Adding free gain to the system 1115
A more selective filter 1115
Conclusion 1115
499 Baseband circuits for an RFID receiver 1116
Introduction 1116
A direct conversion receiver 1116
A low noise differential to single-ended amplifier 1117
A matched I and Q filter and a dual ADC 1117
Conclusion 1117
500 WCDMA ACPR and AltCPR measurements 1118
Introduction 1118
501 Low distortion, low noise differential amplifier drives high speed ADCs in demanding communications transceivers 1120
Introduction 1120
LT1993-x features 1120
High speed ADC driving 1120
WCDMA amplifier and ADC driver 1121
Conclusion 1121
502 Wideband RF ICs for power detection and control 1122
Introduction 1122
A dual band mobile phone transmitter power control application 1122
An RFID reader application 1123
Application of RF power detectors at frequencies above 7GHz 1123
503 Fiber optic communication systems benefit from tiny, low noise avalanche photodiode bias supply 1124
Conclusion 1125
504 ADSL modems that yield long reach and fast data rates 1126
LT1886: low distortion line driver 1126
LT1886 frequency response 1127
A circuit “trick” for a gain of less than 10 1127
505 A low power, high output current dual CFA makes xDSL line driving clean and easy 1128
Introduction 1128
A low distortion HDSL line driver 1129
Performance 1129
Conclusion 1129
506 A low cost 4Mbps IrDA receiver in MS8 and SO-8 packages 1130
Introduction 1130
LT1328 functional description 1130
IrDA SIR 1131
IrDA FIR 1131
4ppm 1131
Conclusion 1131
507 Telephone ring-tone generation 1132
Requirements 1132
An open-architecture ring-tone generator 1132
Not your standard bench supply 1132
Quad op amp rings phones 1132
Index 1134