LTC3882_15 Datasheet, PDF (2/104 Pages) Linear Technology – Dual Output PolyPhase Step-Down DC/DC Voltage Mode Controller with Digital Power System Management

LTC3882
TABLE OF CONTENTS
Features.............................................................. 1
Applications......................................................... 1
Typical Application .................................................1
Description.......................................................... 1
Absolute Maximum Ratings.......................................4
Order Information...................................................4
Electrical Characteristics..........................................4
Pin Configuration...................................................4
Typical Performance Characteristics............................8
Pin Functions...................................................... 11
Block Diagram..................................................... 13
Test Circuit......................................................... 14
Timing Diagram................................................... 14
Operation.......................................................... 14
Overview...................................................................... 14
Main Control Loop........................................................ 15
Power-Up and Initialization.......................................... 17
Soft-Start..................................................................... 18
Time-Based Output Sequencing................................... 18
Output Ramping Control.............................................. 18
Voltage-Based Output Sequencing............................... 18
Output Disable.............................................................. 18
Minimum Output Disable Times................................... 19
Output Short Cycle....................................................... 19
Light Load Current Operation....................................... 19
Switching Frequency and Phase.................................. 19
PolyPhase Load Sharing..............................................20
Active Voltage Positioning............................................20
Input Supply Monitoring..............................................20
Output Voltage Sensing and Monitoring......................20
Output Current Sensing and Monitoring......................21
External and Internal Temperature Sense....................21
Resistor Configuration Pins.........................................21
Internal EEPROM with CRC..........................................22
Fault Detection.............................................................22
Input Supply Faults......................................................22
Hardwired PWM Response to V_OUT Faults...................22
Power Good Indication.................................................23
Hardwired PWM Response to I_OUT Faults....................23
Hardwired PWM Response to Temperature Faults.......23
Hardwired PWM Response to Timing Faults................23
External Faults..............................................................24
Fault Handling..............................................................24
Status Registers and ALERT Masking..........................24
Mapping Faults to GPIO Pins........................................26
Other GPIO Uses..........................................................26
Fault Logging................................................................26
Factory Default Operation............................................29
Serial Interface.............................................................30
Serial Bus Addressing..................................................30
Serial Bus Timeout.......................................................34
Serial Communication Errors.......................................34
PMBus Command Summary.................................... 35
PMBus Commands.......................................................35
Data Formats................................................................35
Applications Information........................................ 40
Efficiency Considerations.............................................40
PWM Frequency and Inductor Selection......................40
Power MOSFET Selection.............................................41
MOSFET Driver Selection.............................................42
Using PWM Protocols..................................................42
C_IN Selection................................................................43
C_OUT Selection..............................................................44
Feedback Loop Compensation.....................................44
PCB Layout Considerations..........................................46
Output Current Sensing................................................47
Output Voltage Sensing................................................49
Soft-Start and Stop......................................................49
Time-Based Output Sequencing and Ramping.............50
Voltage-Based Output Sequencing...............................51
Using Output Voltage Servo.........................................52
Using AVP....................................................................52
PWM Frequency Synchronization................................53
PolyPhase Operation and Load Sharing.......................54
External Temperature Sense........................................56
Resistor Configuration Pins.........................................58
Internal Regulator Outputs...........................................59
IC Junction Temperature..............................................60
Derating EEPROM Retention at Temperature...............60
Configuring Open-Drain Pins.......................................60
PMBus Communication and Command Processing.....61
Status and Fault Log Management...............................62
LTpowerPlay – An Interactive Digital Power GUI..........63
Interfacing to the DC1613.............................................63
Design Example............................................................64
PMBus COMMAND DETAILS..................................... 66
Addressing and Write Protect...........................................66
PAGE............................................................................66
PAGE_PLUS_WRITE....................................................66
PAGE_PLUS_READ......................................................67
WRITE_PROTECT........................................................67
MFR_ADDRESS...........................................................68
MFR_RAIL_ADDRESS.................................................68
General Device Configuration...........................................68
PMBUS_REVISION.......................................................68
CAPABILITY.................................................................68
MFR_CONFIG_ALL_LTC3882......................................69
On, Off and Margin Control...............................................69
ON_OFF_CONFIG..........................................................69
OPERATION..................................................................70
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