Application Note 66 August 1996 Linear Technology Magazine Circuit Collection, Volume II Power Products Richard Markell, Editor INTRODUCTION Application Note 66 is a compendium of “power circuits” included here are circuits that provide 300W or more of from the first five years of Linear Technology. The objective power factor corrected DC from a universal input. Battery is to collect the useful circuits from the magazine into chargers are included, some that charge several battery several applications notes (another, AN67, will collect types, some that are optimized to charge a single type. signal processing circuits into one Application Note) so MOSFET drivers, high side switches and H-bridge driver that valuable “gems” will not be lost. This Application Note circuits are also included, as is an article on simple thermal contains circuits that can power most any system you can analysis. With these introductory remarks, I’ll stand aside imagine, from desktop computer systems to micropower and let the authors describe their circuits. systems for portable and handheld equipment. Also ARTICLE INDEX REGULATORS—SWITCHING (BUCK) High Power (>4A) Big Power for Big Processors: The LTC®1430 Synchronous Regulator ............................................................. 4 Applications for the LTC1266 Switching Regulator ............................................................................................ 5 A High Efficiency 5V to 3.3V/5A Converter ......................................................................................................... 7 High Current, Synchronous Step-Down Switching Regulator ............................................................................ 8 Medium Power (1A to 4A) 1MHz Step-Down Converter Ends 455kHz IF Woes ......................................................................................... 10 High Output Voltage Buck Regulator ................................................................................................................ 11 The LTC1267 Dual Switching Regulator Controller Operates from High Input Voltages................................... 12 High Efficiency 5V to 3.3V/1.25A Converter in 0.6 Square Inches.................................................................... 13 LT ®1074/LT1076 Adjustable 0V to 5V Power Supply....................................................................................... 14 Triple Output 3.3V, 5V and 12V High Efficiency Notebook Power Supply ........................................................ 15 The New SO-8 LTC1147 Switching Regulator Controller Offers High Efficiency in a Small Footprint............... 17 The LT1432: 5V Regulator Achieves 90% Efficiency ........................................................................................ 20 Low Power (<1A) Applications for the LTC1265 High Efficiency Monolithic Buck Converter........................................................ 22 REGULATORS—SWITCHING (BOOST) Medium Power (1A to 4A) High Output Current Boost Regulator............................................................................................................... 24 Low Power (<1A) Applications for the LT1372 500kHz Switching Regulator ............................................................................... 25 , LTC and LT are registered trademarks of Linear Technology Corporation. AN66-1 Application Note 66 REGULATORS—SWITCHING (BUCK/BOOST) ±5V Converter Uses Off-the-Shelf Surface Mount Coil..................................................................................... 27 Switching Regulator Provides Constant 5V Output from 3.5V to 40V Input Without a Transformer ................ 28 Switching Regulator Provides ±15V Output from an 8V to 40V Input Without a Transformer ......................... 29 REGULATORS—SWITCHING (INVERTING) High Efficiency 12V to –12V Converter ............................................................................................................ 32 Regulated Charge Pump Power Supply............................................................................................................ 34 Applications for the LTC1265 High Efficiency Monolithic Buck Converter........................................................ 22 LTC1174: A High Efficiency Buck Converter ..................................................................................................... 35 REGULATORS—SWITCHING (FLYBACK) Applications for the LT1372 500kHz Switching Regulator ............................................................................... 25 REGULATORS—SWITCHING (POWER FACTOR CORRECTED) The New LT1508/LT1509 Combines Power Factor Correction and a PWM in a Single Package ...................... 37 REGULATORS—SWITCHING (DISCUSSION) Adding Features to the Boost Topology............................................................................................................ 39 Sensing Negative Outputs ................................................................................................................................ 40 REGULATORS—SWITCHING (MICROPOWER) 3-Cell to 3.3V Buck/Boost Converter ................................................................................................................ 41 LT1111 Isolated 5V Switching Power Supply................................................................................................... 41 Low Noise Portable Communications DC/DC Converter................................................................................... 43 Applications for the LT1302 Micropower DC/DC Converter ............................................................................. 44 Clock-Synchronized Switching Regulator Has Coherent Noise ........................................................................ 49 Battery-Powered Circuits Using the LT1300 and LT1301 ................................................................................. 51 LTC1174: A High Efficiency Buck Converter ..................................................................................................... 35 Battery-Powered Circuits Using the LT1304 Micropower DC/DC Converter with Low-Battery Detector ........... 54 Automatic Load Sensing Saves Power in High Voltage Converter.................................................................... 57 REGULATORS—SWITCHING (MICROPOWER) Backlight High Efficiency EL Driver Circuit....................................................................................................................... 58 A Low Power, Low Voltage CCFL Power Supply .............................................................................................. 60 All Surface Mount EL Panel Driver Operates from 1.8V to 8V Input ................................................................. 61 A Dual Output LCD Bias Voltage Generator ...................................................................................................... 62 LCD Bias Supply............................................................................................................................................... 63 REGULATORS—SWITCHING (MICROPOWER) Switched Capacitor Regulated Charge Pump Power Supply............................................................................................................ 34 REGULATORS—SWITCHING (MICROPOWER) VPP Generator LTC1262 Generates 12V for Programming Flash Memories Without Inductors ............................................... 64 Flash Memory VPP Generator Shuts Down with 0V Output ............................................................................. 64 AN66-2 Application Note 66 REGULATORS—LINEAR Low Noise Wireless Communications Power Supply ....................................................................................... 65 An LT1123 Ultralow Dropout 5V Regulator ...................................................................................................... 66 REGULATORS—LINEAR Microprocessor Power LT1580 Low Dropout Regulator Uses New Approach to Achieve High Performance ....................................... 67 LT1585: New Linear Regulator Solves Load Transients ................................................................................... 68 BATTERY CHARGERS Charging NiMH/NiCd or Li-Ion with the LT1510 ............................................................................................... 70 Lithium-Ion Battery Charger ............................................................................................................................. 71 Simple Battery Charger Runs at 1MHz ............................................................................................................. 73 A Perfectly Temperature Compensated Battery Charger................................................................................... 74 A Simple 300mA NiCd Battery Charger ............................................................................................................ 75 High Efficiency (>90%) NiCd Battery Charger Circuit Programmable for 1.3A Fast Charge or 100mA Trickle Charge.................................................................................................................................. 76 POWER MANAGEMENT LT1366 Rail-to-Rail Amplifier Controls Topside Current .................................................................................. 78 An Isolated High Side Driver ............................................................................................................................ 79 LTC1163: 2-Cell Power Management