Datasheet LTC7818 (Analog Devices) - 2
| Manufacturer | Analog Devices |
| Description | 40V, Low IQ, 3MHz, Triple Output Buck/Buck/Boost Synchronous Controller |
| Pages / Page | 44 / 2 — TABLE OF CONTENTS Features ... 1. Applications .. 1. Typical Application … |
| Revision | A |
| File Format / Size | PDF / 5.4 Mb |
| Document Language | English |
TABLE OF CONTENTS Features ... 1. Applications .. 1. Typical Application .. 1. Description.. 1. Absolute Maximum Ratings .. 3
Model Line for this Datasheet
Text Version of Document
link to page 1 link to page 1 link to page 1 link to page 1 link to page 3 link to page 3 link to page 3 link to page 4 link to page 7 link to page 11 link to page 13 link to page 14 link to page 14 link to page 14 link to page 14 link to page 14 link to page 14 link to page 15 link to page 15 link to page 16 link to page 16 link to page 16 link to page 17 link to page 17 link to page 17 link to page 17 link to page 17 link to page 18 link to page 18 link to page 18 link to page 18 link to page 19 link to page 20 link to page 21 link to page 22 link to page 23 link to page 24 link to page 24 link to page 25 link to page 26 link to page 26 link to page 26 link to page 26 link to page 27 link to page 28 link to page 29 link to page 29 link to page 29 link to page 30 link to page 30 link to page 30 link to page 30 link to page 30 link to page 31 link to page 32 link to page 32 link to page 34 link to page 35 link to page 37 link to page 42 link to page 43 link to page 44 link to page 44 LTC7818
TABLE OF CONTENTS Features ... 1
Low Value Resistor Current Sensing ... 19
Applications .. 1
Inductor DCR Current Sensing ..20
Typical Application .. 1
Setting the Operating Frequency...21
Description.. 1
Selecting the Light Load Operating Mode ...22
Absolute Maximum Ratings .. 3
Power MOSFET Selection ...23
Order Information .. 3
Boost CIN and COUT Selection ...24
Pin Configuration .. 3
Buck CIN and COUT Selection ..24
Electrical Characteristics ... 4
Setting the Buck Output Voltage ...25
Typical Performance Characteristics ... 7
Setting Boost Output Voltage (VPRG3 Pin) ..26
Pin Functions ..11
RUN Pins and Undervoltage Lockout ..26
Functional Diagram ..13
Soft-Start and Tracking (TRACK/SS1, TRACK/
Operation...14
SS2, SS3 Pins) ...26 Main Control Loop .. 14 Single Output Two-Phase Operation ...27 Power and Bias Supplies (VBIAS, EXTVCC, INTVCC Regulators ..28 and INTVCC) .. 14 Topside MOSFET Driver Supply (CB, DB) ..29 Shutdown and Start-Up (RUN1, RUN2, RUN3 Minimum On-Time Considerations..29 and TRACK/SS1, TRACK/SS2, SS3 Pins) ... 14 Boost Channel Current Monitor (IMON3) ..29 Light Load Operation: Burst Mode Operation, Pulse- Fault Conditions: Buck Current Limit and Foldback .. 30 Skipping, or Forced Continuous Mode (MODE Pin) ..15 Fault Conditions: Buck Overvoltage Protection Frequency Selection, Spread Spectrum, and Phase- (Crowbar) ..30 Locked Loop (FREQ and PLLIN/SPREAD Pins) ... 16 Fault Conditions: Overtemperature Protection ..30 Boost Control er Operation When VIN > VOUT ... 16 Phase-Locked Loop and Frequency Synchronization .. 30 Boost Control er at Low Input Voltage .. 17 Efficiency Considerations ...31 Buck Control er Output Overvoltage Protection .. 17 Checking Transient Response ...32 Buck Foldback Current .. 17 Buck Design Example ...32 Channel 1 Power Good (PGOOD1) .. 17 PC Board Layout Checklist ...34 Boost Overvoltage Indicator (OV3) ... 17 PC Board Layout Debugging ...35
Applications Information ..18 Typical Applications ..37
Inductor Value Calculation .. 18
Package Description ...42
Inductor Core Selection .. 18
Revision History ..43
Current Sense Selection ... 18
Typical Application ...44 Related Parts ..44
Rev. A 2 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
TABLE OF CONTENTS Features ... 1
Low Value Resistor Current Sensing ... 19
Applications .. 1
Inductor DCR Current Sensing ..20
Typical Application .. 1
Setting the Operating Frequency...21
Description.. 1
Selecting the Light Load Operating Mode ...22
Absolute Maximum Ratings .. 3
Power MOSFET Selection ...23
Order Information .. 3
Boost CIN and COUT Selection ...24
Pin Configuration .. 3
Buck CIN and COUT Selection ..24
Electrical Characteristics ... 4
Setting the Buck Output Voltage ...25
Typical Performance Characteristics ... 7
Setting Boost Output Voltage (VPRG3 Pin) ..26
Pin Functions ..11
RUN Pins and Undervoltage Lockout ..26
Functional Diagram ..13
Soft-Start and Tracking (TRACK/SS1, TRACK/
Operation...14
SS2, SS3 Pins) ...26 Main Control Loop .. 14 Single Output Two-Phase Operation ...27 Power and Bias Supplies (VBIAS, EXTVCC, INTVCC Regulators ..28 and INTVCC) .. 14 Topside MOSFET Driver Supply (CB, DB) ..29 Shutdown and Start-Up (RUN1, RUN2, RUN3 Minimum On-Time Considerations..29 and TRACK/SS1, TRACK/SS2, SS3 Pins) ... 14 Boost Channel Current Monitor (IMON3) ..29 Light Load Operation: Burst Mode Operation, Pulse- Fault Conditions: Buck Current Limit and Foldback .. 30 Skipping, or Forced Continuous Mode (MODE Pin) ..15 Fault Conditions: Buck Overvoltage Protection Frequency Selection, Spread Spectrum, and Phase- (Crowbar) ..30 Locked Loop (FREQ and PLLIN/SPREAD Pins) ... 16 Fault Conditions: Overtemperature Protection ..30 Boost Control er Operation When VIN > VOUT ... 16 Phase-Locked Loop and Frequency Synchronization .. 30 Boost Control er at Low Input Voltage .. 17 Efficiency Considerations ...31 Buck Control er Output Overvoltage Protection .. 17 Checking Transient Response ...32 Buck Foldback Current .. 17 Buck Design Example ...32 Channel 1 Power Good (PGOOD1) .. 17 PC Board Layout Checklist ...34 Boost Overvoltage Indicator (OV3) ... 17 PC Board Layout Debugging ...35
Applications Information ..18 Typical Applications ..37
Inductor Value Calculation .. 18
Package Description ...42
Inductor Core Selection .. 18
Revision History ..43
Current Sense Selection ... 18
Typical Application ...44 Related Parts ..44
Rev. A 2 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
