Datasheet LT8708-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | 80V Synchronous 4-Switch Buck-Boost DC/DC Slave Controller for LT8708 Multiphase System |
| Pages / Page | 36 / 1 — FEATURES. DESCRIPTION. Slave Chip of LT8708 to Deliver Additional Power. … |
| Revision | A |
| File Format / Size | PDF / 2.0 Mb |
| Document Language | English |
FEATURES. DESCRIPTION. Slave Chip of LT8708 to Deliver Additional Power. Good Current Matching to the Average Output
Model Line for this Datasheet
Text Version of Document
LT8708-1 80V Synchronous 4-Switch Buck-Boost DC/DC Slave Controller for LT8708 Multiphase System
FEATURES DESCRIPTION
n
Slave Chip of LT8708 to Deliver Additional Power
The LT®8708-1 is a high performance buck-boost n
Good Current Matching to the Average Output
switching regulator controller that is paralleled with the
Current of LT8708 Through Current Regulation
LT8708 to add power and phases to an LT8708 system. n
Easily Paralleled with LT8708 Through Four Pins
The LT8708-1 always operates as a slave to the master n
Synchronized Start-Up with LT8708
LT8708 and has the capability of delivering as much cur- n
Same Conduction Modes as LT8708
rent or power as the master. One or more slaves can be n
Synchronous Rectification: Up to 98% Efficiency
connected to a single master, proportionally increasing n Frequency Range: 100kHz to 400kHz power and current capability of the system. n Available in 40-Lead (5mm × 8mm) QFN with High The LT8708-1 has the same conduction modes as LT8708, Voltage Pin Spacing allowing the LT8708-1 to conduct current and power in the same direction(s) as the master. The master controls
APPLICATIONS
the overall current and voltage limits for an LT8708 mul- n High Voltage Buck-Boost Converters tiphase system, and the slaves comply with these limits. n Bidirectional Charging Systems LT8708-1s can be easily paralleled with the LT8708 by n Automotive 48V Systems connecting four signals together. Two additional current All registered trademarks and trademarks are the property of their respective owners. limits (forward VIN current and reverse VIN current) are available on each slave that can be set independently.
TYPICAL APPLICATION The LT8708-1 Two-Phase 12V Bidirectional Dual Battery System with FHCM and RHCM Efficiency Efficiency
100 10V TO 16V VBAT1 VBAT2 BATTERY 10V TO 16V 99 BATTERY 98 TO DIODE TO DIODE DB1 DB2 97 EFFICIENCY (%) 96 TG1 BOOST1 SW1 BG1 CSP CSN GND BG2 SW2 BOOST2 TG2 95 CSNIN CSPOUT VBAT2 = 13.5V MASTER V LD033 BAT2 CHARGING CURRENT = 30A CSPIN CSNOUT 94
LT8708*
VINCHIP EXTV 10 12 14 16 CC SHDN VOUTLOMON LD033 VBAT1 (V) SWEN SWEN INTV 87081 TA01b CC RVSOFF RVSOFF LT8708-1 SLAVE CLKOUT SYNC GATEVCC *REFER TO ICP ICP LT8708 DATA ICN ICN DIR IMON_OP SHEET FOR VINHIMON IMON_ON MASTER SETUP DB1 DB2 IMON_INP DIR IMON_INN RVS (0V) FWD (3V) TO TO FBIN LD033 MODE VC RT SS CLKOUT FBOUT BOOST1 BOOST2 POWER TRANSFER LD033 DECISION LOGIC 120kHz 87081 TA01a Rev 0 Document Feedback For more information www.analog.com 1 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
FEATURES DESCRIPTION
n
Slave Chip of LT8708 to Deliver Additional Power
The LT®8708-1 is a high performance buck-boost n
Good Current Matching to the Average Output
switching regulator controller that is paralleled with the
Current of LT8708 Through Current Regulation
LT8708 to add power and phases to an LT8708 system. n
Easily Paralleled with LT8708 Through Four Pins
The LT8708-1 always operates as a slave to the master n
Synchronized Start-Up with LT8708
LT8708 and has the capability of delivering as much cur- n
Same Conduction Modes as LT8708
rent or power as the master. One or more slaves can be n
Synchronous Rectification: Up to 98% Efficiency
connected to a single master, proportionally increasing n Frequency Range: 100kHz to 400kHz power and current capability of the system. n Available in 40-Lead (5mm × 8mm) QFN with High The LT8708-1 has the same conduction modes as LT8708, Voltage Pin Spacing allowing the LT8708-1 to conduct current and power in the same direction(s) as the master. The master controls
APPLICATIONS
the overall current and voltage limits for an LT8708 mul- n High Voltage Buck-Boost Converters tiphase system, and the slaves comply with these limits. n Bidirectional Charging Systems LT8708-1s can be easily paralleled with the LT8708 by n Automotive 48V Systems connecting four signals together. Two additional current All registered trademarks and trademarks are the property of their respective owners. limits (forward VIN current and reverse VIN current) are available on each slave that can be set independently.
TYPICAL APPLICATION The LT8708-1 Two-Phase 12V Bidirectional Dual Battery System with FHCM and RHCM Efficiency Efficiency
100 10V TO 16V VBAT1 VBAT2 BATTERY 10V TO 16V 99 BATTERY 98 TO DIODE TO DIODE DB1 DB2 97 EFFICIENCY (%) 96 TG1 BOOST1 SW1 BG1 CSP CSN GND BG2 SW2 BOOST2 TG2 95 CSNIN CSPOUT VBAT2 = 13.5V MASTER V LD033 BAT2 CHARGING CURRENT = 30A CSPIN CSNOUT 94
LT8708*
VINCHIP EXTV 10 12 14 16 CC SHDN VOUTLOMON LD033 VBAT1 (V) SWEN SWEN INTV 87081 TA01b CC RVSOFF RVSOFF LT8708-1 SLAVE CLKOUT SYNC GATEVCC *REFER TO ICP ICP LT8708 DATA ICN ICN DIR IMON_OP SHEET FOR VINHIMON IMON_ON MASTER SETUP DB1 DB2 IMON_INP DIR IMON_INN RVS (0V) FWD (3V) TO TO FBIN LD033 MODE VC RT SS CLKOUT FBOUT BOOST1 BOOST2 POWER TRANSFER LD033 DECISION LOGIC 120kHz 87081 TA01a Rev 0 Document Feedback For more information www.analog.com 1 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
