Datasheet LTC3889 (Analog Devices) - 10

LTC3889
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25C, VIN = 16V, EXTVCC = 0V, unless otherwise noted. Efficiency vs Load Current, Efficiency vs Load Current, Efficiency and Power Loss VOUT = 5V VOUT = 24V vs Input Voltage
95 100 98.0 12 CCM CCM EFFICIENCY DCM DCM POWER LOSS 98 97.5 11 89 POWER LOSS (W) 96 97.0 10 83 94 96.5 9 77 EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%) 96.0 8 V 92 IN = 48V V I V IN = 48V OUT = 20A 71 OUT = 5V V V f OUT = 24V OUT = 12V SW = 150kHz 90 f 95.5 f 7 L = 6.8µH SW = 150kHz SW = 150kHz L = 6.8µH L = 6.8µH DCR = 0.88mΩ DCR = 0.88mΩ DCR = 0.88mΩ 65 88 95.0 6 0 4 8 12 16 20 0 4 8 12 16 20 18 24 30 36 42 48 54 LOAD CURRENT (A) LOAD CURRENT (A) VIN (V) 3889 G02 3889 G01 3889 G03
EXTVCC Switchover Load Step Load Step vs Temperature (Forced Continuous Mode) (Pulse-Skipping Mode)
5.40 ILOAD ILOAD 5.39 5A/DIV 5A/DIV 5.38 INDUCTOR INDUCTOR CURRENT CURRENT (V) 5A/DIV 5A/DIV 5.37 V CC EXT VOUT VOUT 5.36 100mV/DIV 100mV/DIV AC-COUPLED AC-COUPLED 5.35 V 3889 G05 3889 G06 IN = 12V 50µs/DIV VIN = 12V 50µs/DIV VOUT = 1.8V VOUT = 1.8V 0.3A TO 5A STEP 0.3A TO 5A STEP 5.34–50 –25 0 25 50 75 100 125 TEMPERATURE (°C) 3889 G04
Inductor Current at Light Load Start-Up into a Pre-Biased Load Soft-Start Ramp
FORCED CONTINUOUS RUN RUN MODE 1V/DIV 1V/DIV 2A/DIV VOUT V 2.5V/DIV OUT 2.5V/DIV PULSE-SKIPPING MODE 2A/DIV V 3889 G07 3889 G08 3889 G09 IN = 12V 1µs/DIV tRISE = 10ms 5ms/DIV tRISE = 10ms 5ms/DIV VOUT = 1.8V tDELAY = 5ms tDELAY = 5ms ILOAD = 100µA VOUT = 2V Rev. 0 10 For more information www.analog.com Document Outline Table of Contents Features Applications Typical Application Description Table of Contents Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Overview Main Control Loop EEPROM CRC Protection Power-Up and Initialization Soft-Start Time-Based Sequencing Event-Based Sequencing Shutdown Light-Load Current Operation PWM Loop Compensation Switching Frequency and Phase Output Voltage Sensing Output Current Sensing Input Current Sensing PolyPhase Load Sharing External/Internal Temperature Sense RCONFIG (Resistor Configuration) Pins Fault Handling Status Registers and ALERT Masking Mapping Faults to FAULT Pins Power Good Pins 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 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 Optional Schottky Diode Selection CIN and COUT Selection Variable Delay Time, Soft-Start and Output Voltage Ramping Digital Servo Mode Soft Off (Sequenced Off) DRVCC Regulator Topside MOSFET Driver Supply (CB, DB) Undervoltage Lockout Fault Indications Open-Drain Pins Phase-Locked Loop and Frequency Synchronization Minimum On-Time Considerations External Temperature Sense Derating EEPROM Retention at Temperature 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 PC Board Layout Checklist PC Board Layout Debugging Design Example Additional Design Checks Connecting the USB to I2C/SMBus/PMBus Adapter to the LTC3889 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 EEPROM Memory Commands Store/Restore Fault Logging Fault Log Operation Block Memory Write/Read Typical Applications Package Description Typical Application Related Parts