link to page 77 link to page 77 link to page 77 link to page 78 link to page 78 link to page 82 link to page 82 link to page 84 link to page 85 link to page 87 link to page 89 link to page 92 link to page 95 link to page 97 link to page 99 link to page 106 link to page 108 link to page 108 link to page 110 link to page 116 link to page 121 link to page 128 link to page 129 link to page 131 link to page 132 link to page 132 link to page 132 LTM4677 Table oF conTenTs Appendix A ...77 Fault Response ...99 Similarity Between PMBus, SMBus and I2C Fault Sharing ... 106 2-Wire Interface ..77 Scratchpad ... 108 Appendix B ...78 Identification ... 108 PMBus Serial Digital Interface ..78 Fault Warning and Status .. 110 Appendix C: PMBus Command Details ..82 Telemetry .. 116 Addressing and Write Protect ...82 NVM (EEPROM) Memory Commands .. 121 General Configuration Registers ...84 Package Description ... 128 On/Off/Margin ..85 Package Photograph ... 129 PWM Config ...87 Revision History .. 131 Voltage ..89 Typical Application ... 132 Current ..92 Design Resources .. 132 Temperature ..95 Related Parts .. 132 Timing ..97 4677fa For more information www.linear.com/LTM4677 3 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Simplified Block Diagram Decoupling Requirements Functional Diagram Test Circuits Operation Power Module Introduction Power Module Configurability and Readback Data Time-Averaged and Peak Readback Data Power Module Overview EEPROM Serial Interface Device Addressing Fault Detection and Handling Responses to VOUT and IOUT Faults Responses to Timing Faults Responses to SVIN OV Faults Responses to OT/UT Faults Responses to External Faults Fault Logging Bus Timeout Protection PMBus Command Summary PMBus Commands Applications Information VIN to VOUT Step-Down Ratios Input Capacitors Output Capacitors Light Load Current Operation Switching Frequency and Phase Minimum On-Time Considerations Variable Delay Time, Soft-Start and Output Voltage Ramping Digital Servo Mode Soft Off (Sequenced Off) Undervoltage Lockout Fault DETECTION AND HANDLING Open-Drain Pins Phase-Locked Loop and Frequency Synchronization RCONFIG Pin-Straps (External Resistor Configuration Pins) Voltage Selection Connecting the USB to the I2C/SMBus/PMBus Controller to the LTM4677 In System PMBus Communication and Command Processing Thermal Considerations and Output Current Derating Applications Information-Derating Curves EMI Performance Safety Considerations Layout Checklist/Example Typical Applications Appendix A Similarity Between PMBus, SMBus and I2C 2-Wire Interface Appendix B PMBus Serial Digital Interface Appendix C: PMBus Command Details Addressing and Write Protect General Configuration Registers On/Off/Margin PWM Config Voltage Current Temperature Timing Fault Response Fault Sharing Scratchpad Identification Fault Warning and Status Telemetry NVM (EEPROM) Memory Commands Package Description Package Photograph Revision History Typical Application Design Resources Related Parts