POWER LOSS (W) 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 V Range: 4.5V to 38V unique architecture that enhances the signal-to-noise ratio IN n V Range: Up to 3.5V (LOWDCR Pin = INTV ) of the current sense signal, allowing the use of sub-milliohm OUT CC 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 6177787, 6304066, 6580258. 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 V IN Dual Phase Efficiency and Power Loss 7V TO 14V vs Output Current, Sub-Milliohm DCR 4.7F vs Traditional DCR V INTV IN CC 100 14 TG0 LTC3874 V = 12V IN 0.33H V = 1.8V PHASMD BOOST0 OUT (0.32m DCR) V OUT 12 0.1F CCM 95 1.8V LOWDCR SW0 120A EXTV BG0 + 10 CC EFFICIENCY 470F 90k 90 931 2 FREQ + I 8 SENSE0 ILIM 0.22F 85 I SENSE0 6 POWER LOSS 80 LTC3884 RUN0 RUN0 TG1 4 0.33H RUN1 RUN1 0.1F 0.32m BOOST1 (0.32m DCR) GPIO0 FAULT0 1.5m 75 2 SW1 0.32m GPIO1 FAULT1 1.5m PGOOD0 MODE0 BG1 + + 70 0 V SENSE0 470F PGOOD1 MODE1 0 10 20 30 40 50 60 GND + 2 I I V TH0 TH0 SENSE1 931 LOAD CURRENT (A) + I I 3874 TA01b TH1 TH1 I SENSE1 SYNC SYNC 0.22F I SENSE1 3874 TA02 3874fb 1 For more information www.linear.com/LTC3874 EFFICIENCY (%)LTC3874 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V ............................................................. 0.3V to 40V IN BOOST0, BOOST1 ...................................... 0.3V to 46V SW0, SW1 .................................................... 5V to 40V 28 27 26 25 24 23 (BOOST0-SW0), (BOOST1-SW1) ................. 0.3V to 6V MODE0 1 22 BOOST0 + + I , I , I , I ... 0.3V to INTV + SENSE0 SENSE0 SENSE1 SENSE1 CC I 2 21 BG0 SENSE0 EXTV , INTV , RUN0, RUN1 .................... 0.3V to 6V CC CC I 3 20 V SENSE0 IN MODE0, MODE1, ILIM, LOWDCR, RUN0 4 19 INTV 29 CC GND RUN1 5 18 EXTV PHASMD, FREQ .................................... 0.3V to INTVcc CC I 6 17 BG1 SENSE1 SYNC, FAULT0, FAULT1, I , I ......... 0.3V to INTVcc TH0 TH1 + I 7 16 BOOST1 SENSE1 INTV Peak Output Current ................................100mA CC MODE1 8 15 SW1 Operating Junction Temperature Range 9 10 11 12 13 14 (Note 2) .................................................. 40C to 125C Storage Temperature Range .................. 65C to 150C UFD PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN = 43C/W, = 3.4C/W JA JC EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3874EUFD PBF LTC3874EUFD TRPBF 3874 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3874IUFD PBF LTC3874IUFD TRPBF 3874 28-Lead (4mm 5mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: