Datasheet LTC7818 (Analog Devices) - 8

LTC7818
TYPICAL PERFORMANCE CHARACTERISTICS Efficiency and Power Loss Efficiency Efficiency and Power Loss Efficiency vs Output Current (Boost) vs Output Current (Boost) vs Output Current (Boost) vs Output Current (Boost) Efficiency vs Input V Efficiency vs Input V oltage (Boost) oltage (Boost)
100 100 100 100 BURST EFFICIENCY FIGURE 10 CIRCUIT 90 V PULSE–SKIPPING MODE 95 IN = 8V 98 VOUT = 10V 80 PULSE–SKIPPING 10 EFFICIENCY 90 96 70 POWER LOSS (W) VIN = 5V I FCM EFFICIENCY LOAD = 2A 60 1 85 94 ILOAD = 4A 50 FCM LOSS 80 92 40 BURST 0.1 90 EFFICIENCY (%) 75 EFFICIENCY (%) EFFICIENCY (%) 30 PULSE LOSS SKIPPING 70 88 20 LOSS V 0.01 IN = 5V FIGURE 10 CIRCUIT V 10 86 OUT = 10V 65 BURST MODE OPERATION FIGURE 10 CIRCUIT VOUT = 10V 0 0.001 60 84 0.0001 0.001 0.01 0.1 1 10 0.0001 0.001 0.01 0.1 1 10 0 2 4 6 8 10 OUTPUT CURRENT (A) OUTPUT CURRENT (A) INPUT VOLTAGE (V) 7818 G10 7818 G11 7818 G12
Load Step (Boost) Load Step (Boost) Load Step (Boost) Load Step (Boost) Load Step (Boost) Load Step (Boost) Burst Mode Operation Pulse-Skipping Mode Pulse–Skipping Mode Forced Continuous Mode
VOUT3 VOUT3 VOUT3 500mV/DIV 500mV/DIV 500mV/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 100µs/DIV 7818 G13 100µs/DIV 7818 G14 100µs/DIV 7818 G15 VIN = 5V VIN = 5V VIN = 5V VOUT = 10V VOUT = 10V VOUT = 10V 300mA TO 3.3A LOAD STEP 300mA TO 3.3A LOAD STEP 300mA TO 3.3A LOAD STEP FIGURE 10 CIRCUIT FIGURE 10 CIRCUIT FIGURE 10 CIRCUIT
Inductor Current at Light Load Inductor Current at Light Load Boost Regulated Feedback (Boost) Soft Start-Up (Boost) Soft Start–Up (Boost) Voltage vs Temperature
1.207 FORCED RUN3 1.204 CONTINUOUS 5V/DIV MODE 1.201 TAGE (V) 1.198 BURST MODE OPERATION 1.195 5A/DIV VOUT3 PULSE 2V/DIV 1.192 SKIPPING TED FEEDBACK VOL MODE 1.189 GND 7818 G17 4µs/DIV 7818 G16 2ms/DIV REGULA 1.186 VIN = 5V V V IN = 5V OUT = 10V 1.183 NO LOAD FIGURE 10 CIRCUIT –55 –25 5 35 65 95 125 155 FIGURE 10 CIRCUIT TEMPERATURE (oC) 7818 G18 Rev. A 8 For more information www.analog.com 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