LTC4449 datasheet(2/108 Pages) LINER

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LTC3882-1

Rev A

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TABLE OF CONTENTS

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

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

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

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

Absolute Maximum Ratings.............................. 4

Order Information.......................................... 4

Pin Configuration .......................................... 4

Electrical Characteristics................................. 5

Typical Performance Characteristics ................... 9

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

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

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

Timing Diagram...........................................16

Operation...................................................16

Overview ............................................................ 16

Main Control Loop.............................................. 17

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

Soft-Start ...........................................................20

Time-Based Output Sequencing .........................20

Output Ramping Control.....................................20

Voltage-Based Output Sequencing .....................20

Minimum Output Disable Times .........................21

Output Short Cycle .............................................21

Light Load Current Operation .............................21

Switching Frequency and Phase.........................21

PolyPhase Load Sharing.....................................22

Active Voltage Positioning..................................22

Input Supply Monitoring.....................................22

Output Voltage Sensing and Monitoring.............22

Output Current Sensing and Monitoring.............22

External and Internal Temperature Sense ...........23

Resistor Configuration Pins................................23

Internal EEPROM with CRC and ECC .................. 24

Fault Detection.................................................... 24

Input Supply Faults............................................. 24

Hardwired PWM Response to VOUT Faults .........24

Power Good Indication (Master).........................25

Power Good Indication (Slave) ...........................25

Hardwired PWM Response to IOUT Faults ..........25

Hardwired PWM Response to Temperature Faults.. 25

Hardwired PWM Response to Timing Faults ......26

External Faults....................................................26

Fault Handling.....................................................26

Status Registers and ALERT Masking.................26

FAULT Pin I/O......................................................28

Fault Logging......................................................28

Factory Default Operation...................................31

Serial Interface ...................................................32

Serial Bus Addressing ........................................32

Serial Bus Timeout .............................................36

Serial Communication Errors..............................36

PMBus Command Summary ............................37

PMBus Commands.............................................37

Data Formats......................................................37

Applications Information ................................42

Efficiency Considerations ...................................42

PWM Frequency and Inductor Selection.............42

Power MOSFET Selection...................................43

MOSFET Driver Selection ...................................44

Using PWM Protocols ........................................44

CIN Selection.......................................................44

COUT Selection....................................................45

Feedback Loop Compensation............................46

PCB Layout Considerations ................................47

Output Current Sensing......................................48

Output Voltage Sensing......................................50

Soft-Start and Stop ............................................ 51

Time-Based Output Sequencing and Ramping ... 51

Voltage-Based Output Sequencing .....................52

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

Using AVP ..........................................................54

PWM Frequency Synchronization.......................55

PolyPhase Operation and Load Sharing .............56

External Temperature Sense...............................60

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

Internal Regulator Outputs .................................62

IC Junction Temperature.....................................62

Derating EEPROM Retention at Temperature......63

Configuring Open-Drain Pins..............................63

PMBus Communication and Command Processing..64

Status and Fault Log Management .....................65

LTpowerPlay – An Interactive Digital Power GUI... 65

Interfacing to the DC1613...................................66

Design Example..................................................66

PMBus COMMAND DETAILS.............................69

Addressing and Write Protect.................................69

PAGE ..................................................................69

PAGE_PLUS_WRITE ..........................................69

PAGE_PLUS_READ............................................70

WRITE_PROTECT...............................................70

MFR_ADDRESS .................................................71

MFR_RAIL_ADDRESS .......................................71

General Device Configuration .................................71

PMBUS_REVISION.............................................71

CAPABILITY........................................................71

On, Off and Margin Control.....................................72

ON_OFF_CONFIG................................................72

MFR_CONFIG_ALL_LTC3882-1 .........................72

OPERATION........................................................73

MFR_RESET.......................................................73

PWM Configuration ................................................ 74

FREQUENCY_SWITCH........................................ 74

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