LTM4677 datasheet(2/110 Pages) AD

2 / 110 page

LTC3888-1

Rev. 0

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TABLE OF CONTENTS

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

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

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

Description.................................................. 1

Absolute Maximum Ratings.............................. 5

Order Information.......................................... 5

Pin Configuration .......................................... 5

Electrical Characteristics................................. 6

Typical Performance Characteristics ..................10

Pin Functions ..............................................13

Block Diagram.............................................15

Test Circuit.................................................16

Operation...................................................18

Overview................................................................. 18

About This Document......................................... 18

Major Product Features .......................................... 18

Main Control Loop.................................................. 19

Power-Up and Initialization ..................................... 19

Testing Integrity of Output Voltage Sense ..........21

Analog Output Voltage Control ...............................21

PMBus Output Voltage Control...............................21

Soft-Start................................................................21

Time-Based Output Sequencing .............................22

Output Ramping Control.........................................22

Voltage-Based Output Sequencing .........................22

Output Disable........................................................22

Minimum Output Disable Times .........................23

Output Short Cycle .................................................23

Switching Frequency and Phase .............................23

PolyPhase Load Sharing......................................... 24

Voltage Control Loop Compensation ...................... 24

Load Step Emulation............................................... 24

Input Supply Monitoring......................................... 24

Output Voltage Sensing and Monitoring .................25

Output Current Sensing and Monitoring .................25

Temperature Sense.................................................25

Resistor Configuration Pins....................................25

Internal EEPROM with CRC.....................................26

Fault Detection........................................................26

Input Supply Faults.............................................26

Hardwired PWM Response to Power

Stage Faults........................................................26

Hardwired PWM Response to Power Stage UV..27

Hardwired PWM Response to VOUT Faults .........27

Power Good Indication .......................................27

Hardwired PWM Response to IOUT Faults ..........27

Hardwired PWM Response to Internal

Temperature Faults.............................................28

External Temperature Faults...............................28

Timing Faults......................................................28

External Faults....................................................28

Higher-Level Fault Handling ....................................28

Status Registers and ALERT Masking.....................29

FAULT Pin I/O..........................................................29

Fault Log Operation ................................................31

Fault Log Details.................................................31

Factory Default Operation.......................................34

Serial Interface .......................................................35

Serial Bus Addressing ........................................39

Serial Bus Timeout .............................................39

Serial Communication Errors..............................39

PMBus Command Summary ............................40

PMBus Commands.............................................40

Data Formats......................................................40

Applications Information ................................45

Efficiency Considerations .......................................45

Power Stage Selection and Interface ......................45

Using The VDR Monitor..........................................47

Unused TSNS Inputs ..............................................47

PWM Frequency and Inductor Selection.................47

CIN Selection...........................................................48

COUT Selection........................................................49

Programmable Loop Compensation .......................49

PCB Layout Considerations .................................... 51

Output Voltage Sensing ..........................................52

Classical Analog Output Voltage Control ................52

PMBus Output Voltage Control...............................53

Using Output Voltage Servo....................................54

Soft-Start and Stop.................................................54

Time-Based Output Sequencing and Ramping .......54

Voltage-Based Output Sequencing .........................56

PWM Frequency Synchronization...........................56

PolyPhase Operation and Load Sharing..................57

Resistor Configuration Pins....................................60

Internal Regulator Outputs......................................61

IC Junction Temperature.........................................61

Derating EEPROM Retention at Temperature..........62

Configuring Open-Drain Pins..................................62

PMBus Communication and Command Processing63

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