POWERLOSS (W) LTC3882 Dual Output PolyPhase Step-Down DC/DC Voltage Mode Controller with Digital Power System Management FEATURES DESCRIPTION 2 n PMBus/I C Compliant Serial Interface The LTC 3882 is a dual, PolyPhase DC/DC synchronous n Monitor Voltage, Current, Temperature and Faults step-down switching regulator controller with PMBus n compliant serial interface. It uses a constant frequency, Digitally Programmable Voltage, Current Limit, leading-edge modulation, voltage mode architecture for Soft-Start/Stop, Sequencing, Margining, AVP and excellent transient response and output regulation. Each UV/OV Thresholds n PWM channel can produce output voltages from 0.5V to 3V VINSNS 38V, 0.5V V 5.25V OUT 5.25V using a wide range of 3.3V compatible power stages, n 0.5% Output Voltage Accuracy including power blocks, DrMOS or discrete FET drivers. n Programmable PWM Frequency or External Clock Up to four LTC3882s can operate in parallel for 2-, 3-, 4-, Synchronization from 250kHz to 1.25MHz 6- or 8-phase operation. n Accurate PolyPhase Current Sharing n Internal EEPROM with Fault Logging and ECC LTC3882 system configuration and monitoring is sup- n IC Supply Range: 3V to 13.2V ported by the LTpowerPlay software tool. The devices n Resistor or Inductor DCR Current Sensing serial interface can be used to read back input voltage, n Optional Resistor Programming for Key Parameters output voltage and current, temperature and fault status. n 40-Pin (6mm 6mm) QFN Package A wide range of operating parameters can be set via the n AEC-Q100 Qualified for Automotive Applications digital interface or stored in internal EEPROM for use at power up. Switching frequency and phase, output volt - APPLICATIONS age and device address can also be programmed using n external configuration resistors. High Current Distributed Power Systems n All registered trademarks and trademarks are the property of their respective owners. Protected Servers, Network and Storage Equipment by U.S. Patents, including 5396245, 5859606, 6144194, 6937178, 7420359 and 7000125. n Intelligent Energy Efficient Power Regulation n Industrial/Telecom/ATE Systems TYPICAL APPLICATION V IN 7V TO 13.2V + V VINSNS Efficiency and Power Loss vs CC V SENSE0 Load Current FB0 V FDMF5820DC IN 92 13 LTC3882 V OUT 91 PWM SW 1V 90 11 SDA COMP0 80A SCL 89 COMP1 ALERT TO/FROM GND 88 9 PWM0 MCU RUN0 87 TSNS0 RUN1 86 7 + WP I SENSE0 85 GPIO0 I TO/FROM SENSE0 + 84 5 EXTERNAL DEVICES GPIO1 V SENSE1 83 TO/FROM OTHER SHARE CLK I SENSE1 OTHER PHASES + V = 12V SYNC 82 3 I IN SENSE1 V = 1V OUT 81 I FDMF5820DC SYNC = 500kHz AVG0 V IN 80 1 SW I AVG1 0 10 20 30 40 50 60 70 80 PWM1 PWM GND LOAD CURRENT (A) 3882 TA01b TSNS1 I AVG GND V SENSE0 GND INDUCTORS: COOPER FP1007R1-R22 3882 TA01a SOME DETAILS OMITTED FOR CLARITY Rev. C 1 For more information www.analog.com EFFICIENCY (%)LTC3882 TABLE OF CONTENTS Features .............................................................1 PMBus Command Summary ................................... 36 Applications ........................................................1 PMBus Commands ......................................................36 Typical Application ................................................1 Data Formats ...............................................................36 Description..........................................................1 Applications Information ....................................... 41 Absolute Maximum Ratings ......................................4 Efficiency Considerations ............................................41 Order Information ..................................................4 PWM Frequency and Inductor Selection .....................41 Pin Configuration ..................................................4 Power MOSFET Selection ............................................42 Electrical Characteristics .........................................5 MOSFET Driver Selection ............................................43 Block Diagram .................................................... 14 Using PWM Protocols .................................................43 Test Circuit ........................................................ 15 C Selection ...............................................................44 IN Timing Diagram .................................................. 15 C Selection .............................................................45 OUT Operation.......................................................... 15 Feedback Loop Compensation ....................................45 Overview .....................................................................15 PCB Layout Considerations .........................................47 Output Current Sensing ...............................................48 Main Control Loop .......................................................16 Power-Up and Initialization..........................................18 Output Voltage Sensing ...............................................50 Soft-Start ....................................................................19 Soft-Start and Stop .....................................................50 Time-Based Output Sequencing ..................................19 Time-Based Output Sequencing and Ramping ............51 Output Ramping Control .............................................19 Voltage-Based Output Sequencing ..............................52 Voltage-Based Output Sequencing ..............................19 Using Output Voltage Servo ........................................53 Output Disable .............................................................19 Using AVP ...................................................................53 Minimum Output Disable Times ..................................20 PWM Frequency Synchronization ...............................55 Output Short Cycle ......................................................20 PolyPhase Operation and Load Sharing ......................55 Light Load Current Operation ......................................20 External Temperature Sense .......................................58 Switching Frequency and Phase .................................20 Resistor Configuration Pins ........................................59 PolyPhase Load Sharing .............................................21 Internal Regulator Outputs ..........................................60 Active Voltage Positioning ...........................................21 IC Junction Temperature .............................................61 Input Supply Monitoring .............................................21 Derating EEPROM Retention at Temperature ..............61 Output Voltage Sensing and Monitoring .....................21 Configuring Open-Drain Pins ......................................61 Output Current Sensing and Monitoring .....................22 PMBus Communication and Command Processing ....62 Status and Fault Log Management ..............................63 External and Internal Temperature Sense....................22 Resistor Configuration Pins ........................................22 LTpowerPlay An Interactive Digital Power GUI .........64 Internal EEPROM with ECC and CRC ...........................23 Interfacing to the DC1613 ............................................64 Fault Detection ............................................................23 Design Example ...........................................................65 Input Supply Faults .....................................................23 PMBus COMMAND DETAILS .................................... 67 Hardwired PWM Response to V Faults ..................23 Addressing and Write Protect ..........................................67 OUT Power Good Indication ................................................24 PAGE ...........................................................................67 Hardwired PWM Response to I Faults ...................24 PAGE PLUS WRITE ...................................................67 OUT Hardwired PWM Response to Temperature Faults ......24 PAGE PLUS READ .....................................................68 Hardwired PWM Response to Timing Faults ...............24 WRITE PROTECT .......................................................68 External Faults .............................................................25 MFR ADDRESS ..........................................................69 Fault Handling .............................................................25 MFR RAIL ADDRESS ................................................69 Status Registers and ALERT Masking .........................25 General Device Configuration ..........................................69 Mapping Faults to GPIO Pins .......................................27 PMBUS REVISION ......................................................69 Other GPIO Uses .........................................................27 CAPABILITY ................................................................69 Fault Logging ...............................................................27 On, Off and Margin Control ..............................................70 Factory Default Operation ...........................................30 ON OFF CONFIG .........................................................70 Serial Interface ............................................................31 MFR CONFIG ALL LTC3882 .....................................70 Serial Bus Addressing .................................................31 OPERATION .................................................................71 Serial Bus Timeout ......................................................35 MFR RESET ................................................................71 Serial Communication Errors ......................................35 PWM Configuration .........................................................72 FREQUENCY SWITCH .................................................72 Rev. C 2 For more information www.analog.com