Datasheet LTC3874-1 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | PolyPhase Step-Down Synchronous Slave Controller with Sub-Milliohm DCR Sensing |
| Pages / Page | 22 / 1 — FeaTures. DescripTion. Phase Extender for High Phase Count Voltage Rails. … |
| File Format / Size | PDF / 1.0 Mb |
| Document Language | English |
FeaTures. DescripTion. Phase Extender for High Phase Count Voltage Rails. Operates with Power Blocks, DrMOS or External
Model Line for this Datasheet
Text Version of Document
LTC3874-1 PolyPhase Step-Down Synchronous Slave Controller with Sub-Milliohm DCR Sensing
FeaTures DescripTion
n
Phase Extender for High Phase Count Voltage Rails
The LTC®3874-1 is a dual PolyPhase® current mode syn- n
Operates with Power Blocks, DrMOS or External
chronous step-down slave controller. It enables high cur-
Gate Drivers and MOSFETs
rent, multiphase applications when paired with a companion n
Accurate Phase-to-Phase Current Sharing
master controller by extending the phase count. Compat- n
Sub-Milliohm DCR Current Sensing
ible master controllers include the LTC3884-1, LTC3774, n
Phase-Lockable Fixed Frequency 250kHz to 1MHz
LTC3875, LTC3877 and LTC3866. The LTC3874-1 employs n
Immediate Response to Master IC's Fault
a unique architecture that enhances the signal-to-noise n Up to 12-Phase Operation ratio of the current sense signal, allowing the use of sub- n
Wide VIN Range: 4.5 to 38V milliohm DC resistance power inductors to maximize n
VOUT Range : Up to 3.5V (LOWDCR Pin High) efficiency while reducing switching jitter. Its peak current Up to 5.5V (LOWDCR Pin Low) mode architecture allows for accurate phase-to-phase n
Proprietary Current Mode Control Loop current sharing even for dynamic loads. n
Programmable CCM/DCM Operation Effectively working with a master controller, the LTC3874-1 n
Programmable Phase Shift Control supports all the programmable features as well as fault n
24-Lead (4mm × 4mm) QFN Package protection. L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and µModule are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective
applicaTions
owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 5408150. n High Current Distributed Power Systems n Telecom, Datacom and Storage Systems n Intelligent Energy Efficient Power Regulation
Typical applicaTion High Efficiency, 4-Phase 1.8V/120A Step-Down Supply
VIN 7V TO 14V
4-Phase Efficiency and Power
VIN
Loss vs Output Current, Sub-
(0.29mΩ DCR) (0.29mΩ DCR) LTC3874-1 0.215µH 0.215µH VOUT
Milliohm DCR vs Traditional
DrMOS PWM0 PWM1 DrMOS 1.8V 120A
DCR
649Ω 649Ω 470µF 100µF 100µF 0.22µF 470µF + 0.22µF 100 20 ×2 ×3 ×3 + ×2 VIN = 12V VOUT = 1.8V I + + 95 f SENSE0 ISENSE1 SW = 425kHz 17 I – – CCM SENSE0 ISENSE1 POWER LOSS (W) 90 14 LTC3884-1 RUN0 RUN0 INTV EFFICIENCY CC RUN1 RUN1 VCC0 4.7µF FAULT0 FAULT0 V 85 11 CC1 FAULT1 FAULT1 PHASMD 1.8V PGOOD0 MODE0 POWER LOSS LDWDCR EFFICIENCY (%) 80 8 V + SENSE0 PGOOD1 MODE1 ILIM 0.29mΩ V + I SENSE1 TH0 ITH0 100k 75 1.5mΩ 5 ITH1 ITH1 FREQ 0.29mΩ SYNC SYNC GND 1.5mΩ 70 2 0 10 20 30 40 50 60 70 80 90 100 110 120 LOAD CURRENT (A) 38741 TA01a 38741 TA01b REFER TO LTC3884-1 DATA SHEET FOR MASTER SETUP PIN NOT USED IN THIS CIRCUIT: EXTVCC 38741f For more information www.linear/LTC3874-1 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Application Related Parts
FeaTures DescripTion
n
Phase Extender for High Phase Count Voltage Rails
The LTC®3874-1 is a dual PolyPhase® current mode syn- n
Operates with Power Blocks, DrMOS or External
chronous step-down slave controller. It enables high cur-
Gate Drivers and MOSFETs
rent, multiphase applications when paired with a companion n
Accurate Phase-to-Phase Current Sharing
master controller by extending the phase count. Compat- n
Sub-Milliohm DCR Current Sensing
ible master controllers include the LTC3884-1, LTC3774, n
Phase-Lockable Fixed Frequency 250kHz to 1MHz
LTC3875, LTC3877 and LTC3866. The LTC3874-1 employs n
Immediate Response to Master IC's Fault
a unique architecture that enhances the signal-to-noise n Up to 12-Phase Operation ratio of the current sense signal, allowing the use of sub- n
Wide VIN Range: 4.5 to 38V milliohm DC resistance power inductors to maximize n
VOUT Range : Up to 3.5V (LOWDCR Pin High) efficiency while reducing switching jitter. Its peak current Up to 5.5V (LOWDCR Pin Low) mode architecture allows for accurate phase-to-phase n
Proprietary Current Mode Control Loop current sharing even for dynamic loads. n
Programmable CCM/DCM Operation Effectively working with a master controller, the LTC3874-1 n
Programmable Phase Shift Control supports all the programmable features as well as fault n
24-Lead (4mm × 4mm) QFN Package protection. L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and µModule are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective
applicaTions
owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258, 5408150. n High Current Distributed Power Systems n Telecom, Datacom and Storage Systems n Intelligent Energy Efficient Power Regulation
Typical applicaTion High Efficiency, 4-Phase 1.8V/120A Step-Down Supply
VIN 7V TO 14V
4-Phase Efficiency and Power
VIN
Loss vs Output Current, Sub-
(0.29mΩ DCR) (0.29mΩ DCR) LTC3874-1 0.215µH 0.215µH VOUT
Milliohm DCR vs Traditional
DrMOS PWM0 PWM1 DrMOS 1.8V 120A
DCR
649Ω 649Ω 470µF 100µF 100µF 0.22µF 470µF + 0.22µF 100 20 ×2 ×3 ×3 + ×2 VIN = 12V VOUT = 1.8V I + + 95 f SENSE0 ISENSE1 SW = 425kHz 17 I – – CCM SENSE0 ISENSE1 POWER LOSS (W) 90 14 LTC3884-1 RUN0 RUN0 INTV EFFICIENCY CC RUN1 RUN1 VCC0 4.7µF FAULT0 FAULT0 V 85 11 CC1 FAULT1 FAULT1 PHASMD 1.8V PGOOD0 MODE0 POWER LOSS LDWDCR EFFICIENCY (%) 80 8 V + SENSE0 PGOOD1 MODE1 ILIM 0.29mΩ V + I SENSE1 TH0 ITH0 100k 75 1.5mΩ 5 ITH1 ITH1 FREQ 0.29mΩ SYNC SYNC GND 1.5mΩ 70 2 0 10 20 30 40 50 60 70 80 90 100 110 120 LOAD CURRENT (A) 38741 TA01a 38741 TA01b REFER TO LTC3884-1 DATA SHEET FOR MASTER SETUP PIN NOT USED IN THIS CIRCUIT: EXTVCC 38741f For more information www.linear/LTC3874-1 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Application Related Parts
