Datasheet LTC7818 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | 40V, Low IQ, 3MHz, Triple Output Buck/Buck/Boost Synchronous Controller |
| Pages / Page | 44 / 9 — TYPICAL PERFORMANCE CHARACTERISTICS. Maximum Current Sense. SENSE1,2–. … |
| Revision | A |
| File Format / Size | PDF / 5.4 Mb |
| Document Language | English |
TYPICAL PERFORMANCE CHARACTERISTICS. Maximum Current Sense. SENSE1,2–. SENSE1,2 and SENSE3+ Current. and SENSE3+ Current
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Text Version of Document
LTC7818
TYPICAL PERFORMANCE CHARACTERISTICS Maximum Current Sense Maximum Current Sense SENSE1,2– SENSE1,2 and SENSE3+ Current and SENSE3+ Current Threshold vs SENSE Common Maximum Current Sense Threshold Threshold vs ITH Voltage Threshold vs ITH V vs Voltage vs V Mode Voltage vs SENSE Common Mode Voltage
50 900 70 PULSE–SKIPPING 40 BURST MODE 800 SENSE1– CURRENT 60 FORCED CONTINUOUS 30 700 50 600 20 500 SENSE2– OR SENSE3+ CURRENT 40 10 400 30 0 300 20 –10 SENSE CURRENT (μA) 200 –20 100 10 MODE = INTV MAXIMUM CURRENT SENSE THRESHOLD (mV) CC –30 0 MAXIMUM CURRENT SENSE THRESHOLD (mV) 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 ITH VOLTAGE (V) SENSE VOLTAGE (V) SENSE VOLTAGE (V) 7818 G19 7818 G20 7818 G21
SENSE1,2– and SENSE3+ Input SENSE1,2–, SENSE3+ Input SENSE1,2+ SENSE1,2 and SEN + SE3− and SENSE3 Input – Input Buck Foldback Current Limit Current vs Temperature Current vs T Current vs Temperature Current vs T
70 900 MODE = INTV 1.0 CC MODE = INTV 800 CC 0.8 60 SENSE = INTV 700 CC+0.5V 0.6 50 600 SENSE = 3.3V 0.4 SENSE = 12V 500 40 0.2 400 0.0 30 300 SENSE = 1V –0.2 20 200 –0.4 SENSE CURRENT (µA) SENSE CURRENT (μA) SENSE = 0V 100 SENSE1– = INTVCC–0.5V –0.6 10 0 –0.8 SENSE2–,SENSE3+ = INTV MAXIMUM CURRENT SENSE THRESHOLD (mV) CC–0.5V 0 –100 –1.0 0 100 200 300 400 500 600 700 800 –55 –25 5 35 65 95 125 155 –55 –25 5 35 65 95 125 155 FEEDBACK VOLTAGE (mV) TEMPERATURE (oC) TEMPERATURE (oC) 7818 G22 7818 G23 7818 G24
Oscillator Frequency Oscillator Frequency Boost Current Monitor Voltage Boost Channel Current Monitor vs Temperature vs T Output Voltage Noise Spectrum Output V vs Sense Voltage Output vs Sense Voltage
10 0 1.6 R FIGURE 14 CIRCUIT, V FREQ=374k (100kHz) OUT = 5V MODE = INTVCC 8 R –10 DETECTOR = PEAK–HOLD FREQ=75k (500kHz) 1.4 VSENSE3+ = 12V R RBW = 5.1kHz FREQ=12.5k (3MHz) –20 6 FREQ=GND (380kHz) PLLIN/SPREAD = GND 1.2 FREQ=INTVCC (2.25MHz) –30 4 TAGE (V) –40 1.0 PLLIN/SPREAD = INTVCC 2 –50 0.8 0 –60 0.6 AMPLITUDE (dBm) –70 –2 0.4 CHANGE IN FREQUENCY (%) –80 IMON3 OUTPUT VOL –4 –90 0.2 –6 –100 0 –55 –25 5 35 65 95 125 155 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 –30 –20 –10 0 10 20 30 40 50 60 TEMPERATURE (oC) FREQUENCY (MHz) V + – SENSE3 – VSENSE3 (mV) 7818 G25 7818 G26 7818 G27 Rev. A For more information www.analog.com 9 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
TYPICAL PERFORMANCE CHARACTERISTICS Maximum Current Sense Maximum Current Sense SENSE1,2– SENSE1,2 and SENSE3+ Current and SENSE3+ Current Threshold vs SENSE Common Maximum Current Sense Threshold Threshold vs ITH Voltage Threshold vs ITH V vs Voltage vs V Mode Voltage vs SENSE Common Mode Voltage
50 900 70 PULSE–SKIPPING 40 BURST MODE 800 SENSE1– CURRENT 60 FORCED CONTINUOUS 30 700 50 600 20 500 SENSE2– OR SENSE3+ CURRENT 40 10 400 30 0 300 20 –10 SENSE CURRENT (μA) 200 –20 100 10 MODE = INTV MAXIMUM CURRENT SENSE THRESHOLD (mV) CC –30 0 MAXIMUM CURRENT SENSE THRESHOLD (mV) 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 ITH VOLTAGE (V) SENSE VOLTAGE (V) SENSE VOLTAGE (V) 7818 G19 7818 G20 7818 G21
SENSE1,2– and SENSE3+ Input SENSE1,2–, SENSE3+ Input SENSE1,2+ SENSE1,2 and SEN + SE3− and SENSE3 Input – Input Buck Foldback Current Limit Current vs Temperature Current vs T Current vs Temperature Current vs T
70 900 MODE = INTV 1.0 CC MODE = INTV 800 CC 0.8 60 SENSE = INTV 700 CC+0.5V 0.6 50 600 SENSE = 3.3V 0.4 SENSE = 12V 500 40 0.2 400 0.0 30 300 SENSE = 1V –0.2 20 200 –0.4 SENSE CURRENT (µA) SENSE CURRENT (μA) SENSE = 0V 100 SENSE1– = INTVCC–0.5V –0.6 10 0 –0.8 SENSE2–,SENSE3+ = INTV MAXIMUM CURRENT SENSE THRESHOLD (mV) CC–0.5V 0 –100 –1.0 0 100 200 300 400 500 600 700 800 –55 –25 5 35 65 95 125 155 –55 –25 5 35 65 95 125 155 FEEDBACK VOLTAGE (mV) TEMPERATURE (oC) TEMPERATURE (oC) 7818 G22 7818 G23 7818 G24
Oscillator Frequency Oscillator Frequency Boost Current Monitor Voltage Boost Channel Current Monitor vs Temperature vs T Output Voltage Noise Spectrum Output V vs Sense Voltage Output vs Sense Voltage
10 0 1.6 R FIGURE 14 CIRCUIT, V FREQ=374k (100kHz) OUT = 5V MODE = INTVCC 8 R –10 DETECTOR = PEAK–HOLD FREQ=75k (500kHz) 1.4 VSENSE3+ = 12V R RBW = 5.1kHz FREQ=12.5k (3MHz) –20 6 FREQ=GND (380kHz) PLLIN/SPREAD = GND 1.2 FREQ=INTVCC (2.25MHz) –30 4 TAGE (V) –40 1.0 PLLIN/SPREAD = INTVCC 2 –50 0.8 0 –60 0.6 AMPLITUDE (dBm) –70 –2 0.4 CHANGE IN FREQUENCY (%) –80 IMON3 OUTPUT VOL –4 –90 0.2 –6 –100 0 –55 –25 5 35 65 95 125 155 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 –30 –20 –10 0 10 20 30 40 50 60 TEMPERATURE (oC) FREQUENCY (MHz) V + – SENSE3 – VSENSE3 (mV) 7818 G25 7818 G26 7818 G27 Rev. A For more information www.analog.com 9 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
