Datasheet LTC3887, LTC3887-1, LTC3887-2 (Analog Devices)

link to page 16 LTC3887/LTC3887-1/ LTC3887-2 Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management
FEATURES DESCRIPTION
n
PMBus/I2C Compliant Serial Interface
The LTC®3887/LTC3887-1/LTC3887-2 are dual, n
Telemetry Read Back includes VIN, IIN, VOUT, IOUT,
PolyPhase DC/DC synchronous step-down switching
Temperature, Duty Cycle and Faults
regulator controllers with an I2C-based PMBus compli- n
Programmable Voltage, Current Limit, Digital
ant serial interface. The controllers use a constant fre-
Soft-Start/Stop, Sequencing, Margining, OV/UV
quency, current mode architecture that is supported by
and Frequency Synchronization (250kHz to 1MHz)
LTpowerPlay® a software development tool with graphical n
±0.5% Output Voltage Accuracy Over Temperature
user interface (GUI). n
Integrated 16-Bit ADC
n
VOUT Range: 0.5V to 5.5V (VOUT0, VOUT1)
Switching frequency, channel phasing, output voltage, n
Internal EEPROM and Fault Logging with ECC
and device address can be programmed using external n
Integrated N-Channel MOSFET Gate Drivers (LTC3887)
configuration resistors. Additionally, parameters can be n Minimum On-Time 45ns set via the digital interface or stored in EEPROM. Voltage, current, internal/external temperature and fault status can n Wide VIN Range: 4.5V to 24V be read back through the bus interface. n Analog Current Mode Control Loop n Remote Differential Sense for PolyPhase® Applications The LTC3887 has integrated gate drivers. The LTC3887-1 n Accurate PolyPhase Current Sharing for Up to Six Phases has three-state PWM pins to drive DrMOS power stages. n Available in a 40-Pin (6mm × 6mm) QFN Package The LTC3887-2 has gate drivers and no LDO and supports n AEC-Q100 Qualified for Automotive Applications VIN up to 34V. The LTC3887 is an enhanced version of the LTC3880 with greater output voltage range and more
APPLICATIONS
digital features. Refer to Operation section for more detail. n High Current Distributed Power Systems 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, 7420359. Licensed under U.S. Patent 7000125 and other related patents worldwide. n Intelligent Energy Efficient Power Regulation
TYPICAL APPLICATION Dual 350kHz 3.3V/0.5V Step-Down Converter
VIN 6V TO 16V
Regulated Output Voltage vs
10µF 1µF
Temperature, VOUT = 0.5V
VIN INTVCC 0.5 TG0 TG1 0.1µF 0.1µF LTC3887 0.4 V 0.56µH BOOST0 BOOST1 1µH V 0.3 OUT0 OUT1 0.5V SW0 SW1 3.3V 0.2 20A 1.58k BG0 BG1 2k 20A 0.1 0.22µF 0.22µF 0 + + ERROR (%) ISENSEO ISENSE1 –0.1 + I – – SENSEO ISENSE1 V OUT 530µF + –0.2 VSENSEO VSENSE1 V – SENSEO –0.3 TSNS0 TSNS1 + –0.4 10nF 10nF 2200pF 2200pF 530µF –0.5 4.99k 6.04k –50 –30 –10 10 30 50 70 90 110 ITHO ITH1 TEMPERATURE (°C) SDA GPIO0 FAULT MANAGEMENT 3887 TA01b *SOME DETAILS OMITTED PMBus SCL GPIO1 FOR CLARITY INTERFACE ALERT RUN0 VDD33 RUN1 VDD25 TO/FROM SHARE_CLK 1µF 1µF OTHER LTC DEVICES SYNC GND WRITE PROTECT WP 3887 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 (NVM) Power Up and Initialization Soft-Start Sequencing EVENT-Based Sequencing Shutdown Light Load Current Operation Switching Frequency and Phase Output Voltage Sensing Current Sensing PolyPhase Load Sharing External/Internal Temperature Sense RCONFIG (Resistor Configuration) Pins Fault Detection and Handling Internal EEPROM with CRC Protection and ECC Serial Interface Communication Protection Device Addressing Responses to VOUT 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/Warn Response External Overtemperature and Undertemperature Fault Response 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 ISENSE+ and ISENSE– Pins Low Value Resistor Current Sensing Inductor DCR Current Sensing Slope Compensation and Inductor Peak Current Inductor Value Calculation Inductor Core Selection Power MOSFET and Schottky Diode (Optional) Selection Variable Delay Time, Soft-Start and Output Voltage Ramping Digital Servo Mode Soft Off (Sequenced Off) INTVCC Regulator Topside MOSFET Driver Supply (CB, DB) (LTC3887, LTC3887-2) Undervoltage Lockout CIN and COUT Selection Fault Conditions Open-Drain Pins Phase-Locked Loop and Frequency Synchronization Minimum On-Time Considerations RCONFIG (External Resistor Configuration Pins) Voltage Selection Frequency and Phase Selection Using RCONFIG Address Selection Using RCONFIG Efficiency Considerations Checking Transient Response PC Board Layout Checklist PC Board Layout Debugging Design Example Additional Design Checks Connecting the USB to the I2C/SMBus/PMBus Controller to the LTC3887 In System LTpowerPlay: An Interactive GUI for Digital Power PMBus Communication and Command Processing PMBus Command Details Addressing and Write Protect General Configuration Registers On/Off/Margin PWM Config Voltage Input Voltage and Limits Output Voltage and Limits Current Input Current Calibration Output Current Calibration Input Current Output Current Temperature External Temperature Calibration External Temperature Limits 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 (EEPROM) Memory Commands Store/Restore Fault Logging Block Memory Write/Read Typical Applications Package Description Revision History Typical Application Related Parts