Datasheet LTC7818 (Analog Devices) - 7

LTC7818
TYPICAL PERFORMANCE CHARACTERISTICS Efficiency and Power Loss Efficiency and Power Loss Efficiency and Power Loss Efficiency and Power Loss vs Output Current (Buck) vs Output Current (Buck) vs Output Current (Buck) vs Output Current (Buck) Efficiency vs Input V Efficiency vs Input V oltage (Buck) oltage (Buck)
100 100 100 100 100 BURST EFFICIENCY VIN = 10V 90 VOUT = 5V PULSE–SKIPPING 90 10 80 10 95 EFFICIENCY 70 EFFICIENCY POWER LOSS (W) FCM EFFICIENCY POWER LOSS (W) 80 1 60 1 90 FCM LOSS 50 70 0.1 40 PULSE–SKIPPING 0.1 POWER LOSS 85 V EFFICIENCY (%) LOSS BURST EFFICIENCY (%) 60 0.01 IN = 10V EFFICIENCY (%) 30 V LOSS OUT = 5V ILOAD = 4A 20 V 0.01 80 IN = 10V 50 0.001 V 10 f OUT = 5V fSW=380kHz (FIGURE 10) SW = 380kHz (FIGURE 10) f FIGURE 10 CIRCUIT fSW=2.25MHz (FIGURE 14) SW = 2.25MHz (FIGURE 14) 0 0.001 40 0.0001 75 0.0001 0.001 0.01 0.1 1 10 0.0001 0.001 0.01 0.1 1 10 4 12 20 28 36 OUTPUT CURRENT (A) OUTPUT CURRENT (A) INPUT VOLTAGE (V) 7818 G01 7818 G02 7818 G03
Load Step (Buck) Load Step (Buck) Load Step (Buck) Load Step (Buck) Load Step (Buck) Load Step (Buck) Burst Mode Operation Pulse-Skipping Mode Pulse–Skipping Mode Forced Continuous Mode Forced Continuous Mode
VOUT VOUT VOUT 200mV/DIV 200mV/DIV 200mV/DIV INDUCTOR INDUCTOR INDUCTOR CURRENT CURRENT CURRENT 5A/DIV 5A/DIV 5A/DIV LOAD LOAD LOAD CURRENT CURRENT CURRENT 5A/DIV 5A/DIV 5A/DIV 7818 G06 50µs/DIV 7818 G04 50µs/DIV 7818 G05 50µs/DIV VIN = 10V VIN = 10V VIN = 10V VOUT = 5V VOUT = 5V VOUT = 5V 300mA TO 6A LOAD STEP 300mA TO 6A LOAD STEP 300mA TO 6A LOAD STEP FIGURE 10 CIRCUIT FIGURE 10 CIRCUIT FIGURE 10 CIRCUIT
Inductor Current at Light Load Inductor Current at Light Load Buck Regulated Feedback V Buck Regulated Feedback oltage (Buck) Soft Start-Up Soft Start–Up vs T V emperature oltage vs Temperature
808 FORCED 806 RUN1,2 CONTINUOUS 5V/DIV MODE 804 TAGE (mV) V TAGE OUT2 802 BURST MODE 1V/DIV OPERATION VOL 800 2A/DIV VOUT1 PULSE 1V/DIV 798 SKIPPING MODE TED FEEDBACK VOL 796 4µs/DIV 7818 G07 1ms/DIV 7818 G08 794 V REGULA IN = 10V V V IN = 10V OUT = 5V FIGURE 10 CIRCUIT 792 NO LOAD –55 –25 5 35 65 95 125 155 FIGURE 10 CIRCUIT TEMPERATURE (oC) 7818 G09 Rev. A For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Main Control Loop Power and Bias Supplies (VBIAS, EXTVCC, and INTVCC) Shutdown and Start-Up (RUN1, RUN2, RUN3 and TRACK/SS1, TRACK/SS2, SS3 Pins) Light Load Operation: Burst Mode Operation, Pulse-Skipping, or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) Boost Controller Operation When VIN > VOUT Boost Controller at Low Input Voltage Buck Controller Output Overvoltage Protection Buck Foldback Current Channel 1 Power Good (PGOOD1) Boost Overvoltage Indicator (OV3) Applications Information Inductor Value Calculation Inductor Core Selection Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Current Sensing Setting the Operating Frequency Selecting the Light-Load Operating Mode Power MOSFET Selection Boost CIN and COUT Selection Buck CIN and COUT Selection Setting the Buck Output Voltage Setting Boost Output Voltage (VPRG3 Pin) RUN Pins and Undervoltage Lockout Soft-Start and Tracking (TRACK/SS1, TRACK/SS2, SS3 Pins) Single Output Two-Phase Operation INTVCC Regulators Topside MOSFET Driver Supply (CB, DB) Minimum On-Time Considerations Boost Channel Current Monitor (IMON3) Fault Conditions: Buck Current Limit and Foldback Fault Conditions: Buck Overvoltage Protection (Crowbar) Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Buck Design Example PC Board Layout Checklist PC Board Layout Debugging Typical Applications Package Description Revision History Typical Application Related Parts