Datasheet LTC3421 (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: 12µA
0.10Ω N-channel MOSFET switch and a 0.14Ω 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 12µA 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 <1µA 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 QFN Package Other features include: 1µA shutdown, antiringing control, thermal limit and reference output.
APPLICATIONS
The LTC3421 is available in a small 4mm × 4mm QFN n Handheld Computers package. n Cordless Phones All registered trademarks and trademarks are the property of their respective owners. n GPS Receivers n Battery Backup Supplies
TYPICAL APPLICATION 2-Cell to 3.3V Efficiency
4.7µH VIN 100 1.8V TO 3V Burst Mode OPERATION 2 21 14 15 16 90 4.7µF VIN = 3V VIN = 2.4V SHDN VIN SW SW SW 80 4 18 VOUT VIN = 2V ENB VOUTS 3.3V 70 3 17 VREF VOUT 1A 60 23 19 LBI V 340k OUT 2 50 22 20 CELLS LBO LTC3421 VOUT 40 7 1 SYNC FB EFFICIENCY (%) 22µF 30 8 24 ILIM VC 20 9 BURST 470pF 200k 45.3k 10 VOUT = 3.3V SS R PGND PGND PGND f T GND OSC = 1MHz 20k 100k 0 6 5 10 11 12 13 0.1 1 10 100 1000 0.1µF 28k 0.1µF OUTPUT CURRENT (mA) 3421 G02 3421 TA01 Rev. A Document Feedback For more information www.analog.com 1 Document Outline Description Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Package/Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Low Voltage Start-Up Low Noise Fixed Frequency Operation Burst Mode Operation Output Disconnect and Inrush Limiting Applications Information Component Selection Typical Application Package Description Revision History Typical Application Related Parts