Datasheet LT8708-1 (Analog Devices) - 2
| Manufacturer | Analog Devices |
| Description | 80V Synchronous 4-Switch Buck-Boost DC/DC Slave Controller for LT8708 Multiphase System |
| Pages / Page | 36 / 2 — TABLE OF CONTENTS Features ... 1. Applications .. 1. Typical Application … |
| Revision | A |
| File Format / Size | PDF / 2.0 Mb |
| Document Language | English |
TABLE OF CONTENTS Features ... 1. Applications .. 1. Typical Application .. 1. Description.. 1. Absolute Maximum Ratings .. 3
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TABLE OF CONTENTS Features ... 1
Current Monitoring and Limiting ...21
Applications .. 1
Monitoring: IOUT(SLAVE) ...21
Typical Application .. 1
Monitoring and Limiting: IIN(SLAVE) ..21
Description.. 1
Multiphase Clocking ...22
Absolute Maximum Ratings .. 3 Applications Information ..23 Order Information .. 3
Quick-Start Multiphase Setup ...23
Pin Configuration .. 3
Quick Setup: Design the Master Phase ...23
Electrical Characteristics ... 4
Quick Setup: Design the Slave Phase(s) ...23
Typical Performance Characteristics ... 8
Quick Setup: Evaluation ..23
Pin Functions ..10
Choosing the Total Number of Phases ..23
Block Diagram ...13
Operating Frequency Selection ... 24
Operation...14
CIN and COUT Selection ...24 Common LT8708-1 and LT8708 Features ... 14 CIN and COUT Selection: VIN Capacitance ..24 Adding Phases to an LT8708 Application .. 14 CIN and COUT Selection: VOUT Capacitance ...25 Adding Phases: The Master LT8708 .. 14 VINHIMON, VOUTLOMON and RVSOFF ..25 Adding Phases: The Slave LT8708-1 .. 16 Configuring the IIN(SLAVE) Current Limits ..26 Start-Up .. 17 Regulating IOUT(SLAVE) ..26 Start-Up: SWEN Pin .. 17 IOUT(SLAVE): Circuit Description ...26 Start-Up: Soft-Start of Switching Regulator ... 18 IOUT(SLAVE): Configuration ..28 Control Overview .. 18 Loop Compensation ..28 Power Switch Control .. 19 Voltage Lockouts ..29 Unidirectional and Bidirectional Conduction ... 19 Circuit Board Layout Checklist ...29 Error Amplifiers .. 19 Design Example ...29 Transfer Function: IOUT(SLAVE) Vs IOUT(MASTER) ..20
Typical Applications ..31
Transfer Function: CCM ..21
Package Description ...35
Transfer Function: DCM, HCM and Burst Mode
Typical Application ...36
Operation ..21
Related Parts ..36
Rev 0 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 Block Diagram Operation Applications Information Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Common LT8708-1 and LT8708 Features Adding Phases to an LT8708 Application Adding Phases: The Master LT8708 Adding Phases: The Slave LT8708-1 Start-Up Start-Up: SWEN Pin Start-Up: Soft-Start of Switching Regulator Control Overview Power Switch Control Unidirectional and Bidirectional Conduction Error Amplifiers Transfer Function: IOUT(SLAVE) Vs IOUT(MASTER) Transfer Function: CCM Transfer Function: DCM, HCM and Burst Mode Operation Current Monitoring and Limiting Monitoring: IOUT(SLAVE) Monitoring and Limiting: IIN(SLAVE) Multiphase Clocking Applications Information Quick-Start Multiphase Setup Quick Setup: Design the Master Phase Quick Setup: Design the Slave Phase(s) Quick Setup: Evaluation Choosing the Total Number of Phases Operating Frequency Selection CIN and COUT Selection CIN and COUT Selection: VIN Capacitance CIN and COUT Selection: VOUT Capacitance VINHIMON, VOUTLOMON and RVSOFF Configuring the IIN(SLAVE) Current Limits Regulating IOUT(SLAVE) IOUT(SLAVE): Circuit Description IOUT(SLAVE): Configuration Loop Compensation Voltage Lockouts Circuit Board Layout Checklist Design Example Typical Applications Package Description Typical Application Related Parts
TABLE OF CONTENTS Features ... 1
Current Monitoring and Limiting ...21
Applications .. 1
Monitoring: IOUT(SLAVE) ...21
Typical Application .. 1
Monitoring and Limiting: IIN(SLAVE) ..21
Description.. 1
Multiphase Clocking ...22
Absolute Maximum Ratings .. 3 Applications Information ..23 Order Information .. 3
Quick-Start Multiphase Setup ...23
Pin Configuration .. 3
Quick Setup: Design the Master Phase ...23
Electrical Characteristics ... 4
Quick Setup: Design the Slave Phase(s) ...23
Typical Performance Characteristics ... 8
Quick Setup: Evaluation ..23
Pin Functions ..10
Choosing the Total Number of Phases ..23
Block Diagram ...13
Operating Frequency Selection ... 24
Operation...14
CIN and COUT Selection ...24 Common LT8708-1 and LT8708 Features ... 14 CIN and COUT Selection: VIN Capacitance ..24 Adding Phases to an LT8708 Application .. 14 CIN and COUT Selection: VOUT Capacitance ...25 Adding Phases: The Master LT8708 .. 14 VINHIMON, VOUTLOMON and RVSOFF ..25 Adding Phases: The Slave LT8708-1 .. 16 Configuring the IIN(SLAVE) Current Limits ..26 Start-Up .. 17 Regulating IOUT(SLAVE) ..26 Start-Up: SWEN Pin .. 17 IOUT(SLAVE): Circuit Description ...26 Start-Up: Soft-Start of Switching Regulator ... 18 IOUT(SLAVE): Configuration ..28 Control Overview .. 18 Loop Compensation ..28 Power Switch Control .. 19 Voltage Lockouts ..29 Unidirectional and Bidirectional Conduction ... 19 Circuit Board Layout Checklist ...29 Error Amplifiers .. 19 Design Example ...29 Transfer Function: IOUT(SLAVE) Vs IOUT(MASTER) ..20
Typical Applications ..31
Transfer Function: CCM ..21
Package Description ...35
Transfer Function: DCM, HCM and Burst Mode
Typical Application ...36
Operation ..21
Related Parts ..36
Rev 0 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 Block Diagram Operation Applications Information Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Common LT8708-1 and LT8708 Features Adding Phases to an LT8708 Application Adding Phases: The Master LT8708 Adding Phases: The Slave LT8708-1 Start-Up Start-Up: SWEN Pin Start-Up: Soft-Start of Switching Regulator Control Overview Power Switch Control Unidirectional and Bidirectional Conduction Error Amplifiers Transfer Function: IOUT(SLAVE) Vs IOUT(MASTER) Transfer Function: CCM Transfer Function: DCM, HCM and Burst Mode Operation Current Monitoring and Limiting Monitoring: IOUT(SLAVE) Monitoring and Limiting: IIN(SLAVE) Multiphase Clocking Applications Information Quick-Start Multiphase Setup Quick Setup: Design the Master Phase Quick Setup: Design the Slave Phase(s) Quick Setup: Evaluation Choosing the Total Number of Phases Operating Frequency Selection CIN and COUT Selection CIN and COUT Selection: VIN Capacitance CIN and COUT Selection: VOUT Capacitance VINHIMON, VOUTLOMON and RVSOFF Configuring the IIN(SLAVE) Current Limits Regulating IOUT(SLAVE) IOUT(SLAVE): Circuit Description IOUT(SLAVE): Configuration Loop Compensation Voltage Lockouts Circuit Board Layout Checklist Design Example Typical Applications Package Description Typical Application Related Parts
