Datasheet LTC7804 (Analog Devices) - 7

LTC7804
TYPICAL PERFORMANCE CHARACTERISTICS Efficiency and Power Loss Efficiency and Power Loss vs Output Current vs Output Current vs Output Current Efficiency vs Input Voltage
100 100k 100 10k 100 ILOAD = 3A 90 BURST EFFICIENCY 90 FIGURE 9 CIRCUIT FCM EFFICIENCY BURST EFFICIENCY 99 80 PULSE– 10k 80 1k SKIPPING POWER LOSS (mW) 70 FCM LOSS POWER LOSS (mW) 98 EFFICIENCY 70 VOUT = 24V 60 1k 60 100 BURST LOSS 97 50 50 PULSE–SKIPPING 40 100 40 10 96 LOSS EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%) 30 30 V 95 IN = 12V 20 BURST V 10 20 V 1 IN = 12V OUT = 24V 94 10 LOSS VOUT = 24V Burst Mode OPERATION 10 FIGURE 9 CIRCUIT FIGURE 9 CIRCUIT 0 1 0 0.1 93 0.001 0.01 0.1 1 10 0.00001 0.0001 0.001 0.01 0.1 1 10 0 5 10 15 20 25 OUTPUT CURRENT (A) OUTPUT CURRENT (A) INPUT VOLTAGE (V) 7804 G01 7804 G02 7804 G03
Load Step Forced Load Step Burst Mode Operation Load Step Pulse-Skipping Mode Continuous Mode Forced Continuous Mode
LOAD STEP LOAD STEP LOAD STEP 2A/DIV 2A/DIV 2A/DIV INDUCTOR INDUCTOR CURRENT CURRENT INDUCTOR 5A/DIV 5A/DIV CURRENT 5A/DIV VOUT VOUT VOUT 500mV/DIV 500mV/DIV 500mV/DIV VIN = 12V 200µs/DIV VIN = 12V 200µs/DIV VIN = 12V 200µs/DIV VOUT = 24V VOUT = 24V VOUT = 24V LOAD STEP FROM 200mA TO 2.5A 7804 G04 LOAD STEP FROM 200mA TO 2.5A 7804 G05 LOAD STEP FROM 200mA TO 2.5A 7804 G06 FIGURE 9 CIRCUIT FIGURE 9 CIRCUIT FIGURE 9 CIRCUIT
Regulated Feedback Voltage Inductor Current at Light Load Soft Start-Up vs Temperature vs T
1.212 1.209 FORCED CONTINUOUS 1.206 TAGE (V) MODE 1.203 VOUT 5V/DIV 1.200 5A/DIV Burst Mode 1.197 OPERATION TED FEFEDBACK VOL 1.194 PULSE– SKIPPING 0V REGULA 1.191 MODE 1.188 VIN = 12V 5µs/DIV VIN = 12V 2ms/DIV –55 25 5 35 65 95 125 155 VOUT = 24V VOUT = 24V TEMPERATURE (°C) ILOAD = 200μA 7804 G07 FIGURE 9 CIRCUIT 7804 G08 7804 G09 FIGURE 9 CIRCUIT Rev. 0 For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Main Control Loop INTVCC/EXTVCC Power Boost Supply and Dropout (BOOST and SW Pins) Shutdown and Start-Up (RUN, SS Pins) Light Load Current 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) Operation When VIN > VOUT Operation at Low Input Voltage BOOST Supply Refresh and Internal Charge Pump Applications Information SENSE+ and SENSE– Pins Low Value Resistor Current Sensing Inductor DCR Sensing Inductor Value Calculation Inductor Core Selection Power MOSFET Selection CIN and COUT Selection Setting Output Voltage RUN Pin Soft-Start (SS Pin) INTVCC Regulators Topside MOSFET Driver Supply (CB, DB) Phase-Locked Loop and Frequency Synchronization Setting the Operating Frequency Selecting the Light-Load Operating Mode Minimum On-Time Considerations Fault Conditions: Overtemperature Protection Efficiency Considerations Checking Transient Response Design Example PC Board Layout Checklist PC Board Layout Debugging Package Description Typical Application Related Parts