link to page 1 link to page 1 link to page 1 link to page 1 link to page 3 link to page 3 link to page 3 link to page 4 link to page 8 link to page 10 link to page 15 link to page 15 link to page 16 link to page 16 link to page 16 link to page 16 link to page 16 link to page 17 link to page 17 link to page 18 link to page 18 link to page 18 link to page 21 link to page 21 link to page 23 link to page 23 link to page 23 link to page 24 link to page 24 link to page 24 link to page 24 link to page 27 link to page 28 link to page 28 link to page 29 link to page 29 link to page 29 link to page 31 link to page 31 link to page 32 link to page 32 link to page 32 link to page 32 link to page 32 link to page 33 link to page 33 link to page 34 link to page 35 link to page 35 link to page 36 link to page 36 link to page 38 link to page 38 link to page 38 link to page 38 link to page 45 link to page 45 link to page 46 link to page 46 link to page 46 link to page 46 link to page 48 link to page 56 link to page 56 link to page 56 link to page 57 link to page 58 link to page 58 link to page 59 link to page 59 link to page 60 link to page 60 link to page 60 link to page 60 link to page 63 link to page 63 link to page 64 link to page 65 link to page 66 link to page 66 LTM4641 Table oF conTenTs Features ... 1Applications Information—Load ProtectionApplications .. 1Features ..32Typical Application .. 1 Overcurrent Foldback Protection ..32 Description.. 1 Power Good Indicator and Latching Output Absolute Maximum Ratings .. 3 Overvoltage Protection ...32 Order Information .. 3 Power-Interrupt MOSFET (MSP), CROWBAR Pin Pin Configuration .. 3 and Output CROWBAR MOSFET (MCB) ..33 Electrical Characteristics ... 4 Fast Output Overvoltage Comparator Threshold ...34 Typical Performance Characteristics ... 8 The Switching Node: SW Pin ..35 Pin Functions ..10Applications Information—EMI Performance ..35Simplified Block Diagram ...15Applications Information—MultimoduleDecoupling Requirements ...15Parallel Operation ..36Operation...16Applications Information—Thermal Considerations Introduction .. 16 and Output Current Derating ..38 Motivation ... 16 Thermal Considerations and Power µModule Regulator Reliability .. 16 Output Current Derating ...38 Overview ... 16 Applications Information—Output CapacitanceApplications Information—Power Supply Features .17Table ..45 Power (VINH) and Bias (VINL) Input Pins ... 17 Applications Information—Safety and Layout Switching Frequency (On Time) Selection and Guidance ...46 Voltage Dropout Criteria (Achievable VIN-to-VOUT Safety Considerations ...46 Step-Down Ratios).. 18 Layout Checklist/Example ..46 Setting the Output Voltage; the Differential Typical Applications ..48 Remote Sense Amplifier ...21 Appendices ..56 Input Capacitors ...23 Appendix A. Functional Block Diagram and Output Capacitors and Features Quick Reference Guide ...56 Loop Stability/Loop Compensation ...23 Appendix B. Start-Up/Shutdown State Diagram ...57 Pulse-Skipping Mode vs Appendix C. Switching Frequency Considerations Forced Continuous Mode ... 24 and Usage of RfSET ...58 Soft-Start, Rail-Tracking and Start-Up Into Appendix D. Remote Sensing in Pre-Bias .. 24 Harsh Environments ...59 INTVCC and DRVCC ...27 Appendix E. Inspiration For Pulse-Skipping 1VREF ...28 Mode Operation ..60 TEMP, OTBH and Overtemperature Protection ..28 Appendix F. Adjusting the Fast Output Overvoltage Input Monitoring Pins: UVLO, IOVRETRY, OVLO ..29 Comparator Threshold ..60 Applications Information—Input ProtectionPackage Description ...63Features ..29Package Photo ..63 Start-Up/Shutdown and Run Enable; Package Description ...64 Power-On Reset and Timeout Delay Time ...31 Revision History ..65Typical Application ...66Related Parts ..66 4641fe 2 For more information www.linear.com/LTM4641 Document Outline Features Applications Typical Application Description Table of Contents Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Simplified Block Diagram Decoupling Requirements Operation Applications Information—Power Supply Features Applications Information—Input Protection Features Applications Information—Load Protection Features Applications Information—EMI Performance Applications Information—Multimodule Parallel Operation Applications Information—Thermal Considerations and Output Current Derating Applications Information—Output Capacitance Table Applications Information—Safety and Layout Guidance Typical Applications Appendices Package Description Package Photo Package Description Revision History Typical Application Related Parts