LTC3882
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
Block Diagram..................................................... 14
Test Circuit......................................................... 15
Timing Diagram................................................... 15
Operation.......................................................... 15
Overview...................................................................... 15
Main Control Loop........................................................16
Power-Up and Initialization.......................................... 18
Soft-Start..................................................................... 19
Time-Based Output Sequencing................................... 19
Output Ramping Control.............................................. 19
Voltage-Based Output Sequencing............................... 19
Output Disable.............................................................. 19
Minimum Output Disable Times...................................20
Output Short Cycle.......................................................20
Light Load Current Operation.......................................20
Switching Frequency and Phase..................................20
PolyPhase Load Sharing..............................................21
Active Voltage Positioning............................................21
Input Supply Monitoring..............................................21
Output Voltage Sensing and Monitoring......................21
Output Current Sensing and Monitoring......................22
External and Internal Temperature Sense....................22
Resistor Configuration Pins.........................................22
Internal EEPROM with ECC and CRC............................23
Fault Detection.............................................................23
Input Supply Faults......................................................23
Hardwired PWM Response to VOUT Faults...................23
Power Good Indication.................................................24
Hardwired PWM Response to IOUT Faults....................24
Hardwired PWM Response to Temperature Faults.......24
Hardwired PWM Response to Timing Faults................24
External Faults..............................................................25
Fault Handling..............................................................25
Status Registers and ALERT Masking..........................25
Mapping Faults to GPIO Pins........................................27
Other GPIO Uses..........................................................27
Fault Logging................................................................27
Factory Default Operation............................................30
Serial Interface.............................................................31
Serial Bus Addressing..................................................31
Serial Bus Timeout.......................................................35
Serial Communication Errors.......................................35
PMBus Command Summary.................................... 36
PMBus Commands.......................................................36
Data Formats................................................................36
Applications Information........................................ 41
Efficiency Considerations.............................................41
PWM Frequency and Inductor Selection......................41
Power MOSFET Selection.............................................42
MOSFET Driver Selection.............................................43
Using PWM Protocols..................................................43
CIN Selection................................................................44
COUT Selection..............................................................45
Feedback Loop Compensation.....................................45
PCB Layout Considerations..........................................47
Output Current Sensing................................................48
Output Voltage Sensing................................................50
Soft-Start and Stop......................................................50
Time-Based Output Sequencing and Ramping.............51
Voltage-Based Output Sequencing...............................52
Using Output Voltage Servo.........................................53
Using AVP....................................................................53
PWM Frequency Synchronization................................55
PolyPhase Operation and Load Sharing.......................55
External Temperature Sense........................................58
Resistor Configuration Pins.........................................59
Internal Regulator Outputs...........................................60
IC Junction Temperature..............................................61
Derating EEPROM Retention at Temperature...............61
Configuring Open-Drain Pins.......................................61
PMBus Communication and Command Processing.....62
Status and Fault Log Management...............................63
LTpowerPlay – An Interactive Digital Power GUI..........64
Interfacing to the DC1613.............................................64
Design Example............................................................65
PMBus COMMAND DETAILS..................................... 67
Addressing and Write Protect...........................................67
PAGE............................................................................67
PAGE_PLUS_WRITE....................................................67
PAGE_PLUS_READ......................................................68
WRITE_PROTECT........................................................68
MFR_ADDRESS...........................................................69
MFR_RAIL_ADDRESS.................................................69
General Device Configuration...........................................69
PMBUS_REVISION.......................................................69
CAPABILITY.................................................................69
On, Off and Margin Control...............................................70
ON_OFF_CONFIG..........................................................70
MFR_CONFIG_ALL_LTC3882......................................70
OPERATION..................................................................71
MFR_RESET.................................................................71
PWM Configuration..........................................................72
FREQUENCY_SWITCH..................................................72
Rev. C
2
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