POWER LOSS (W) LTC3884/LTC3884-1 Dual Output PolyPhase Step-Down Controller with Sub-Milliohm DCR Sensing and Digital Power System Management FEATURES DESCRIPTION 2 n PMBus/I C Compliant Serial Interface The LTC 3884/LTC3884-1 are dual output PolyPhase DC/ n Telemetry Read-Back Includes V , I , V , I , DC synchronous step-down switching regulator control- IN IN OUT OUT 2 Temperature and Faults lers with an I C-based PMBus compliant serial interface. n Programmable Voltage, Current Limit, Digital Soft- The controllers employ a constant-frequency current Start/Stop, Sequencing, Margining, OV/UV/OC mode architecture, together with a unique scheme to pro- n Sub-Milliohm DCR Current Sensing vide excellent performance for sub-milliohm DCR appli- n Digitally Adjustable Loop Compensation Parameters cations. The LTC3884/LTC3884-1 are supported by the n 0.5% Output Voltage Accuracy Over Temperature LTpowerPlay software development tool with graphical n Integrated Input Current Sense Amplifier user interface (GUI). n Internal EEPROM with ECC and Fault Logging Programmable loop compensation allows the controller n Integrated N-Channel MOSFET Gate Drivers (LTC3884) to be compensated digitally. Switching frequency, chan- n Power Conversion nel phasing, output voltage, and device address can be n Wide V Range: 4.5V to 38V IN programmed both by the digital interface as well as exter- n V Range: 0.5V to 3.5V (with Low DCR Setting) OUT nal configuration resistors. Additionally, parameters can 0.5V to 5.5V (without Low DCR Setting) be set via the digital interface or stored in EEPROM. Both n Accurate PolyPhase Current Sharing for Up to 6 Phases outputs have independent power good indicators and n AEC-Q100 Qualified for Automotive Applications FAULT function. The LTC3884 has integrated gate drivers. The LTC3884-1 has three-state PWM pins to drive power APPLICATIONS blocks or DrMOS power stages. All registered trademarks and trademarks are the property of their respective owners. Protected n Telecom, Datacom, and Storage Systems by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 5408150, n 7420359, 8648623, 8786265, 8823352, 7000125. Licensed under U.S. Patent 7000125 and Industrial and Point-of-Load Applications other related patents worldwide. TYPICAL APPLICATION 1F 1 2m V IN 6V TO 15V 10F 10F Efficiency and Power Loss 4.7F 2 + 2 270F INTV V I I CC IN IN IN 2 vs Load Current TG0 TG1 0.1F 0.1F 100 6 BOOST0 BOOST1 DCR=0.32m DCR=0.32m SW0 SW1 90 5 L=0.33H L= 0.33H BG0 BG1 LTC3884* 80 4 SDA FAULT0 SCL FAULT1 PMBus FAULT MANAGEMENT ALERT PGOOD0 INTERFACE 70 3 RUN0 PGOOD1 TO/FROM RUN1 SHARE CLK OTHER LTC DEVICES V = 12V IN EXTV CC 60 2 V = 1.8V OUT 931 931 + + EXTV = 0 I I CC SENSE0 SENSE1 f = 350kHz 0.22F 0.22F SW 50 1 I I V SENSE0 SENSE1 V OUT0 OUT1 EFFICIENCY + + 1V 1.8V V V SENSE0 SENSE1 POWER LOSS 30A 30A 40 0 V V SENSE0 SENSE1 0 5 10 15 20 25 30 TSNS0 TSNS1 LOAD CURRENT (A) I I TH0 TH1 330F 330F 3884 TA01b I I THR0 THR1 2 2 V PGND SGND V 10nF 4700pF DD33 DD25 2200pF 10nF 220pF 1F 1F 220pF *SOME DETAILS OMITTED FOR CLARITY 3884 TA01a Rev. G 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC3884/LTC3884-1 TABLE OF CONTENTS Features ..................................................... 1 Responses to V , I and I Faults/Warnings ...32 OUT IN OUT Applications ................................................ 1 Output Overvoltage Fault Response ...................33 Typical Application ........................................ 1 Output Undervoltage Response ..........................33 Description.................................................. 1 Peak Output Overcurrent Fault Response ...........33 Absolute Maximum Ratings .............................. 4 Responses to Timing Faults ....................................33 Pin Configuration .......................................... 4 Responses to V OV Faults ....................................34 IN Order Information .......................................... 5 Responses to OT/UT Faults .....................................34 Electrical Characteristics ................................. 6 Internal Overtemperature Fault Response ..........34 Typical Performance Characteristics .................. 12 External Overtemperature and Undertemperature Pin Functions .............................................. 17 Fault Response ...................................................34 Block Diagram ............................................. 19 Responses to External Faults ..................................34 Operation................................................... 20 Fault Logging ..........................................................34 Overview .................................................................20 Bus Timeout Protection ..........................................35 2 Main Control Loop ..................................................21 Similarity Between PMBus, SMBus and I C EEPROM .................................................................21 2-Wire Interface ......................................................35 Power-Up and Initialization .....................................22 PMBus Serial Digital Interface ................................35 Soft-Start ................................................................23 PMBus Command Summary ............................ 40 Time-Based Sequencing .........................................23 PMBus Commands .................................................40 Voltage-Based Sequencing .....................................23 *Data Format ..........................................................45 Shutdown ............................................................... 24 Applications Information ................................ 46 Light-Load Current Operation ................................. 24 Current Limit Programming ....................................46 Switching Frequency and Phase .............................25 I and I Pins ......................................46 SENSE0 SENSE1 PWM Loop Compensation ......................................25 Inductor DCR Sensing ........................................ 47 Output Voltage Sensing ..........................................25 Inductor Value Calculation ......................................48 INTV /EXTV Power ...........................................25 Inductor Core Selection ..........................................48 CC CC Output Current Sensing and Sub Milliohm DCR Low Value Resistor Current Sensing .......................48 Current Sensing ......................................................26 Slope Compensation and Inductor Peak Current ....49 Input Current Sensing .............................................27 Power MOSFET and Optional Schottky Diode PolyPhase Load Sharing .........................................27 Selection .................................................................50 External/Internal Temperature Sense ......................27 Variable Delay Time, Soft-Start and Output Voltage RCONFIG (Resistor Configuration) Pins ..................28 Ramping .................................................................50 Fault Detection and Handling ..................................29 Digital Servo Mode ................................................. 51 Status Registers and ALERT Masking .................29 Soft Off (Sequenced Off) ........................................52 Mapping Faults to FAULT Pins ............................31 INTV /EXTV Power ...........................................52 CC CC Power Good Pins ................................................31 Topside MOSFET Driver Supply (C , D ) ................53 B B CRC Protection and ECC .....................................31 Undervoltage Lockout .............................................54 Serial Interface .......................................................32 C and C Selection ...........................................54 IN OUT Communication Protection .................................32 Fault Indication .......................................................55 Device Addressing ..................................................32 Open-Drain Pins .....................................................55 Rev. G 2 For more information www.analog.com