LTC3421EUF#PBF Analog Devices

LTC3421 3A, 3MHz Micropower Synchronous Boost Converter with Output Disconnect FEATURES DESCRIPTION n Synchronous Rectification: Up to 96% Efficiency The LTC 3421 is a high efficiency, current mode, fixed n True Output Disconnect frequency, step-up DC/DC converter with true output dis- n Inrush Current Limiting connect and inrush current limiting. The device includes a n Very Low Quiescent Current: 12A 0.10 N-channel MOSFET switch and a 0.14 P-channel n Up to 1.5A Continuous Output Current synchronous rectifier. This product has the ability to sim- n Fixed Frequency Operation Up to 3MHz ply program the output voltage, switching frequency, n 0.5V to 4.5V Input Range current limit, soft-start, Burst Mode threshold and loop n 2.4V to 5.25V Adjustable Output Voltage compensation with external passive components. n Guaranteed 1V Start-Up Quiescent current is only 12A during Burst Mode opera- n Programmable Current Limit tion, maximizing battery life in portable applications. The n Programmable Soft-Start oscillator frequency can be programmed up to 3MHz n Synchronizable Oscillator and can be synchronized to an external clock applied to n Manual or Automatic Burst Mode Operation the SYNC pin. An open-drain uncommitted low-battery n Low-Battery Comparator comparator is included. The part maintains operation in n <1A Shutdown Current applications with a secondary cell powering the output n 1.22V Reference Output Voltage voltage during shutdown. n Small (4mm 4mm) Thermally Enhanced Other features include: 1A shutdown, antiringing control, QFNPackage thermal limit and reference output. APPLICATIONS The LTC3421 is available in a small 4mm 4mm QFN n package. Handheld Computers n All registered trademarks and trademarks are the property of their respective owners. Cordless Phones n GPS Receivers n Battery Backup Supplies TYPICAL APPLICATION 2-Cell to 3.3V Efficiency 4.7H V IN 100 1.8V TO 3V Burst Mode OPERATION 90 2 21 14 15 16 4.7F V = 3V V = 2.4V IN IN SHDN V SW SW SW IN 80 4 18 V V = 2V OUT IN ENB V OUTS 3.3V 70 3 17 1A V V REF OUT 60 23 19 340k LBI V OUT 50 2 22 20 CELLS LBO V LTC3421 OUT 40 7 1 SYNC FB 22F 30 8 24 I V LIM C 20 9 470pF 200k BURST V = 3.3V 10 OUT 45.3k f = 1MHz SS R GND PGND PGND PGND OSC T 100k 20k 0 6 5 10 11 12 13 0.1 1 10 100 1000 0.1F 28k 0.1F OUTPUT CURRENT (mA) 3421 G02 3421 TA01 Rev. A 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC3421 TABLE OF CONTENTS Features ............................................................................................................................ 1 Applications ....................................................................................................................... 1 Typical Application ............................................................................................................... 1 Description......................................................................................................................... 1 Absolute Maximum Ratings ..................................................................................................... 4 Order Information ................................................................................................................. 4 Electrical Characteristics ........................................................................................................ 4 Package/Order Information ...................................................................................................... 4 Electrical Characteristics ........................................................................................................ 5 Typical Performance Characteristics .......................................................................................... 6 Pin Functions ...................................................................................................................... 7 Block Diagram ..................................................................................................................... 9 Operation..........................................................................................................................10 Low Voltage Start-Up ............................................................................................................................................ 10 Low Noise Fixed Frequency Operation .................................................................................................................. 10 Burst Mode Operation ........................................................................................................................................... 11 Output Disconnect and Inrush Limiting ................................................................................................................ 12 Applications Information .......................................................................................................13 Component Selection ............................................................................................................................................ 13 Typical Application ..............................................................................................................16 Package Description ............................................................................................................17 Revision History .................................................................................................................18 Typical Application ..............................................................................................................19 Related Parts .....................................................................................................................19 Rev. A 2 For more information www.analog.com