Datasheet LTC3884, LTC3884-1 (Analog Devices)

LTC3884/LTC3884-1 Dual Output PolyPhase Step-Down Controller with Sub-Milliohm DCR Sensing and Digital Power System Management
FEATURES DESCRIPTION
n
PMBus/I2C Compliant Serial Interface
The LTC®3884/LTC3884-1 are dual output PolyPhase DC/
– Telemetry Read-Back Includes VIN, IIN, VOUT, IOUT,
DC synchronous step-down switching regulator controllers
Temperature and Faults
with an I2C-based PMBus compliant serial interface. The
– Programmable Voltage, Current Limit, Digital Soft-
controllers employ a constant-frequency current mode
Start/Stop, Sequencing, Margining, OV/UV/OC
architecture, together with a unique scheme to provide n
Sub-Milliohm DCR Current Sensing
excellent performance for sub-milliohm DCR applica- n
Digitally Adjustable Loop Compensation Parameters
tions. 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, channel
Power Conversion
phasing, output voltage, and device address can be pro- n Wide VIN Range: 4.5V to 38V grammed both by the digital interface as well as external n VOUT Range: 0.5V to 3.5V (with Low DCR Setting); configuration resistors. Additionally, parameters can be set 0.5V to 5.5V (without Low DCR Setting) via the digital interface or stored in EEPROM. Both outputs n Accurate PolyPhase® Current Sharing for Up to 6 Phases have independent power good indicators and FAULT function. n AEC-Q100 Qualified for Automotive Applications The LTC3884 has integrated gate drivers. The LTC3884-1 has three-state PWM pins to drive power blocks or DrMOS
APPLICATIONS
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 Industrial and Point-of-Load Applications 7420359, 8648623, 8786265, 8823352, 7000125. Licensed under U.S. Patent 7000125 and other related patents worldwide.
TYPICAL APPLICATION
1µF 1Ω 2mΩ VIN
Efficiency and Power Loss
6V TO 15V 10µF 4.7µF 10µF
vs Load Current
×2 INTV + – ×2 270µF CC VIN IIN IIN ×2 TG0 TG1 100 6 0.1µF 0.1µF BOOST0 BOOST1 DCR=0.32mΩ DCR=0.32mΩ 90 5 SW0 SW1 L=0.33µH L= 0.33µH POWER LOSS (W) BG0 BG1 VIN = 12V 80 4 LTC3884* VOUT = 1.8V SDA FAULT0 EXTVCC=0 SCL FAULT1 PMBus FAULT MANAGEMENT 70 fSW=350kHz 3 ALERT PGOOD0 INTERFACE RUN0 PGOOD1 TO/FROM RUN1 SHARE_CLK EFFICIENCY (%) OTHER LTC DEVICES 60 2 EXTVCC 931Ω 931Ω I + + SENSE0 ISENSE1 50 1 0.22µF 0.22µF EFFICIENCY V I – – SENSE0 ISENSE1 V OUT0 OUT1 POWER LOSS 1.8V V + + SENSE0 VSENSE1 1V 40 0 30A V – – 0 5 10 15 20 25 30 SENSE0 VSENSE1 30A TSNS0 TSNS1 LOAD CURRENT (A) I 3884 TA01b TH0 ITH1 330µF 330µF ITHR0 ITHR1 ×2 ×2 10nF 4700pF VDD33 PGND SGND VDD25 2200pF 10nF 220pF 1µF 1µF 220pF *SOME DETAILS OMITTED FOR CLARITY 3884 TA01a Rev. F Document Feedback For more information www.analog.com 1 Document Outline Features Applications Typical Application Description Table of Contents Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Overview Main Control Loop EEPROM Power-Up and Initialization Soft-Start Time-Based Sequencing Voltage-Based Sequencing Shutdown Light-Load Current Operation Switching Frequency and Phase PWM Loop Compensation Output Voltage Sensing INTVCC/EXTVCC Power Output Current Sensing and Sub Milliohm DCR Current Sensing Input Current Sensing PolyPhase Load Sharing External/Internal Temperature Sense RCONFIG (Resistor Configuration) Pins Fault Detection and Handling Status Registers and ALERT Masking Mapping Faults to FAULT Pins Power Good Pins CRC Protection and ECC Serial Interface Communication Protection Device Addressing Responses to VOUT, IIN and IOUT Faults Output Overvoltage Fault Response Output Undervoltage Response Peak Output Overcurrent Fault Response Responses to Timing Faults Responses to VIN OV Faults Responses to OT/UT Faults Internal Overtemperature Fault Response External Overtemperature and Undertemperature Fault Response Responses to Input Overcurrent and Output Undercurrent Faults Responses to External Faults Fault Logging Bus Timeout Protection Similarity Between PMBus, SMBus and I2C 2-Wire Interface PMBus Serial Digital Interface PMBus Command Summary PMBus Commands *Data Format Applications Information Current Limit Programming ISENSE0± and ISENSE1± Pins Inductor DCR Sensing Inductor Value Calculation Inductor Core Selection Low Value Resistor Current Sensing Slope Compensation and Inductor Peak Current Power MOSFET and Optional Schottky Diode Selection Variable Delay Time, Soft-Start and Output Voltage Ramping Digital Servo Mode Soft Off (Sequenced Off) INTVCC/EXTVCC Power Topside MOSFET Driver Supply (CB, DB) Undervoltage Lockout CIN and COUT Selection Fault Indication Open-Drain Pins Phase-Locked Loop and Frequency Synchronization Minimum On-Time Considerations External Temperature Sense Input Current Sense Amplifier External Resistor Configuration Pins (RCONFIG) Voltage Selection Frequency Selection Phase Selection Address Selection Using RCONFIG Efficiency Considerations Programmable Loop Compensation Checking Transient Response PolyPhase Configuration Master Slave Operation PC Board Layout Checklist PC Board Layout Debugging Design Example Additional Design Checks Connecting the USB to I2C/SMBus/PMBus Controller to the LTC3884 in System LTpowerPlay: An Interactive GUI for Digital Power PMBus Communication and Command Processing PMBus Command Details Addressing and Write Protect General Configuration Commands On/Off/Margin PWM Configuration Voltage Input Voltage and Limits Output Voltage and Limits Output Current and Limits Input Current and Limits Temperature External Temperature Calibration Timing Timing—On Sequence/Ramp Timing—Off Sequence/Ramp Precondition for Restart Fault Response Fault Responses All Faults Fault Responses Input Voltage Fault Responses Output Voltage Fault Responses Output Current Fault Responses IC Temperature Fault Responses External Temperature Fault Sharing Fault Sharing Propagation Fault Sharing Response Scratchpad Identification Fault Warning and Status Telemetry NVM Memory Commands Store/Restore Fault Log Operation Fault Logging Block Memory Write/Read Typical Applications Package Description Revision History Typical Application Related Parts