Data Sheet

LTM4640

analog.com

Rev. 0

2 of 38

TABLE OF CONTENTS

Features.................................................................................................................................................................................................1

Applications ..........................................................................................................................................................................................1

General Description ..............................................................................................................................................................................1

Typical Application ...............................................................................................................................................................................1

Revision History ....................................................................................................................................................................................3

Specifications........................................................................................................................................................................................4

Absolute Maximum Ratings ..................................................................................................................................................................6

Thermal Resistance ..........................................................................................................................................................................7

Electrostatic Discharge (ESD)...........................................................................................................................................................7

ESD Ratings.......................................................................................................................................................................................7

ESD Caution ......................................................................................................................................................................................7

Pin Configurations and Function Descriptions ....................................................................................................................................8

Pin Descriptions................................................................................................................................................................................8

Typical Performance Characteristics .................................................................................................................................................11

Theory of Operation............................................................................................................................................................................13

LTM4640 Overview..........................................................................................................................................................................13

Simplified Block Diagram...............................................................................................................................................................14

Decoupling Requirements..............................................................................................................................................................14

Applications Information....................................................................................................................................................................15

VIN to VOUT Step-Down Ratios...........................................................................................................................................................15

Output Voltage Programming........................................................................................................................................................15

Input Decoupling Capacitors..........................................................................................................................................................16

Output Decoupling Capacitors.......................................................................................................................................................16

Discontinuous-Conduction Mode ..................................................................................................................................................16

Forced Continuous Mode ...............................................................................................................................................................17

Operating Frequency......................................................................................................................................................................17

Frequency Synchronization and Clock In ......................................................................................................................................17

Multiphase Operation.....................................................................................................................................................................17

Input RMS Ripple Current Cancellation .........................................................................................................................................18

Soft Start and Output Voltage Tracking.........................................................................................................................................19

Power Good ....................................................................................................................................................................................21

RUN Enable .....................................................................................................................................................................................21

Prebiased Output Startup ..............................................................................................................................................................21

SW Pins and Optional Snubber Circuit...........................................................................................................................................21