Datasheet LTC3874 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | PolyPhase Step-Down Synchronous Slave Controller with Sub-Milliohm DCR Sensing |
| Pages / Page | 30 / 1 — FEATURES. DESCRIPTION. Phase Extender for High Phase Count Voltage Rails. … |
| File Format / Size | PDF / 919 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Phase Extender for High Phase Count Voltage Rails. Accurate Phase-to-Phase Current Sharing
Model Line for this Datasheet
Text Version of Document
LTC3874 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 is a dual PolyPhase® current mode synchro- n
Accurate Phase-to-Phase Current Sharing
nous step-down slave controller. It enables high current, n
Sub-Milliohm DCR Current Sensing
multi-phase applications when paired with a companion n
Phase-Lockable Fixed Frequency 250kHz to 1MHz
master controller by extending the phase count. Compat- n
Immediate Response to Master IC's Fault
ible master controllers include the LTC3884, LTC3866, n Up to 12 Phase Operation LTC3875, LTC3877 and LTC3774. The LTC3874 employs a n Wide VIN Range: 4.5V to 38V unique architecture that enhances the signal-to-noise ratio n VOUT Range: Up to 3.5V (LOWDCR Pin = INTVCC) of the current sense signal, allowing the use of sub-milliohm Up to 5.5V (LOWDCR Pin = OV) DC resistance power inductors to maximize efficiency while n Proprietary Current Mode Control Loop reducing switching jitter. Its peak current mode architecture n Programmable CCM/DCM Operation allows for accurate phase to phase current sharing even n Programmable Phase Shift Control for dynamic loads. n Dual N-Channel MOSFET Gate Drivers Effectively working with a master controller, the LTC3874 n 28-Lead (4mm × 5mm) QFN Package supports all the programmable features as well as fault protection. L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and Burst Mode are registered
APPLICATIONS
trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, n High Current Distributed Power Systems 6177787, 6304066, 6580258. 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
Dual Phase Efficiency and Power Loss
7V TO 14V
vs Output Current, Sub-Milliohm DCR
4.7µF
vs Traditional DCR
VIN INTVCC TG0 100 14 LTC3874 V 0.33µH IN = 12V PHASMD V BOOST0 (0.32mΩ DCR) OUT = 1.8V V 0.1µF OUT 95 12 CCM LOWDCR SW0 1.8V EXTV 120A CC BG0 + 10 POWER LOSS (W) 90k 470µF 90 EFFICIENCY FREQ 931Ω I + ×2 SENSE0 8 ILIM 0.22µF 85 I – SENSE0 POWER LOSS 6 EFFICIENCY (%) LTC3884 RUN0 RUN0 80 TG1 4 RUN1 RUN1 0.1µF 0.33µH 0.32mΩ BOOST1 GPIO0 FAULT0 (0.32mΩ DCR) 75 1.5mΩ 2 SW1 0.32mΩ GPIO1 FAULT1 1.5mΩ PGOOD0 MODE0 BG1 V + + 70 0 SENSE0 PGOOD1 MODE1 470µF GND 0 10 20 30 40 50 60 V + I SENSE1 TH0 ITH0 ×2 931Ω LOAD CURRENT (A) I ITH1 I + 3874 TA01b TH1 SENSE1 SYNC SYNC 0.22µF I – SENSE1 3874 TA02 3874fb For more information www.linear.com/LTC3874 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional 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 Functional Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
FEATURES DESCRIPTION
n
Phase Extender for High Phase Count Voltage Rails
The LTC®3874 is a dual PolyPhase® current mode synchro- n
Accurate Phase-to-Phase Current Sharing
nous step-down slave controller. It enables high current, n
Sub-Milliohm DCR Current Sensing
multi-phase applications when paired with a companion n
Phase-Lockable Fixed Frequency 250kHz to 1MHz
master controller by extending the phase count. Compat- n
Immediate Response to Master IC's Fault
ible master controllers include the LTC3884, LTC3866, n Up to 12 Phase Operation LTC3875, LTC3877 and LTC3774. The LTC3874 employs a n Wide VIN Range: 4.5V to 38V unique architecture that enhances the signal-to-noise ratio n VOUT Range: Up to 3.5V (LOWDCR Pin = INTVCC) of the current sense signal, allowing the use of sub-milliohm Up to 5.5V (LOWDCR Pin = OV) DC resistance power inductors to maximize efficiency while n Proprietary Current Mode Control Loop reducing switching jitter. Its peak current mode architecture n Programmable CCM/DCM Operation allows for accurate phase to phase current sharing even n Programmable Phase Shift Control for dynamic loads. n Dual N-Channel MOSFET Gate Drivers Effectively working with a master controller, the LTC3874 n 28-Lead (4mm × 5mm) QFN Package supports all the programmable features as well as fault protection. L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and Burst Mode are registered
APPLICATIONS
trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, n High Current Distributed Power Systems 6177787, 6304066, 6580258. 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
Dual Phase Efficiency and Power Loss
7V TO 14V
vs Output Current, Sub-Milliohm DCR
4.7µF
vs Traditional DCR
VIN INTVCC TG0 100 14 LTC3874 V 0.33µH IN = 12V PHASMD V BOOST0 (0.32mΩ DCR) OUT = 1.8V V 0.1µF OUT 95 12 CCM LOWDCR SW0 1.8V EXTV 120A CC BG0 + 10 POWER LOSS (W) 90k 470µF 90 EFFICIENCY FREQ 931Ω I + ×2 SENSE0 8 ILIM 0.22µF 85 I – SENSE0 POWER LOSS 6 EFFICIENCY (%) LTC3884 RUN0 RUN0 80 TG1 4 RUN1 RUN1 0.1µF 0.33µH 0.32mΩ BOOST1 GPIO0 FAULT0 (0.32mΩ DCR) 75 1.5mΩ 2 SW1 0.32mΩ GPIO1 FAULT1 1.5mΩ PGOOD0 MODE0 BG1 V + + 70 0 SENSE0 PGOOD1 MODE1 470µF GND 0 10 20 30 40 50 60 V + I SENSE1 TH0 ITH0 ×2 931Ω LOAD CURRENT (A) I ITH1 I + 3874 TA01b TH1 SENSE1 SYNC SYNC 0.22µF I – SENSE1 3874 TA02 3874fb For more information www.linear.com/LTC3874 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional 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 Functional Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts
