POWER LOSS (W) LTC3865/LTC3865-1 Dual, 2-Phase Synchronous DC/DC Controller with Pin Selectable Outputs FEATURES DESCRIPTION n Dual, 180 Phased Controllers The LTC 3865/LTC3865-1 are high performance dual n 2-Pin VID Output Voltage Programming from 0.6V synchronous step-down DC/DC switching regulator to 5V controllers that drive all N-channel synchronous power n High Ef ciency: Up to 95% MOSFET stages. A constant frequency current mode n R or DCR Current Sensing architecture allows a phase-lockable frequency of up to SENSE n Phase-Lockable Fixed Frequency 250kHz to 770kHz 770kHz. Power loss and noise are minimized by operating n Adjustable Current Limit the two controller output stages out of phase. n Dual N-Channel MOSFET Synchronous Drive OPTI-LOOP compensation allows the transient response n Wide V Range: 4.5V to 38V Operation IN to be optimized over a wide range of output capacitance n Adjustable Soft-Start Current Ramping or Tracking and ESR values. Independent track/soft-start pins for n Output OV Protection With Reverse Current Limit each controller ramp the output voltage during start-up. n Power Good Output Voltage Monitor Current foldback limits MOSFET heat dissipation during n 32-Pin 5mm 5mm QFN and 38-Lead TSSOP short-circuit conditions. The MODE/PLLIN pin selects Packages among Burst Mode operation, pulse-skipping mode, and continuous inductor current mode. The output volt- APPLICATIONS ages can be precisely programmed by pin strapping or n DC Power Distribution Systems external resistors. L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Module, Linear Technology and the Linear logo The LTC3865/LTC3865-1 are available in low pro le (5mm are registered trademarks and No R is a trademark of Linear Technology Corporation. All SENSE other trademarks are the property of their respective owners. U.S. Patents, including 5481178, 5mm) 32-pin QFN and 38-Lead thermally enhanced 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. TSSOP packages. TYPICAL APPLICATION High Ef ciency 1.5V/15A, 1.2V/15A Step-Down Converter V IN 4.5V TO 24V + 22F 2.2 Ef ciency and Power Loss 50V 1F vs Load Current 100 10 V = 12V IN 4.7F 90 V = 1.5V OUT V INTV IN CC 80 TG1 TG2 0.1F 0.1F 70 1 EFFICIENCY 0.47H BOOST1 BOOST2 0.47H 60 SW1 SW2 POWER LOSS LTC3865 50 BG2 BG1 40 PGND 0.1 30 FREQ 100 100 + + SENSE1 20 SENSE2 1000pF 2m 1000pF 2m 10 SENSE1 SENSE2 0 0.01 100 100 VID11 VID21 0.01 0.1 1 10 100 VID12 VID22 V V LOAD CURRENT (A) OUT1 OUT2 V V 1.2V 1.5V OSENSE2 OSENSE1 3865 TA01b 15A + I 15A I + TH1 TH2 C 1000pF 1000pF OUT2,3 C TK/SS1 TK/SS2 OUT5,6 SGND 0.1F 0.1F 15k 100F 100F 10k 100pF 162k 100pF 3865 TA01a 3865fb 1 EFFICIENCY (%)LTC3865/LTC3865-1 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) ......................... 0.3V to 40V I , I Voltages .................................... 0.3V to 2.7V IN TH1 TH2 Topside Driver Voltages INTV DC Output Current (Note 9) .......................80mA CC BOOST1, BOOST2 .................................. 0.3V to 46V Operating Junction Temperature Range (Notes 2, 3) Switch Voltage (SW1, SW2) ......................... 5V to 40V LTC3865/LTC3865-1 .......................... 40C to 125C INTV , RUN1, RUN2, PGOOD(s), EXTV , Storage Temperature Range ................... 65C to 125C CC CC (BOOST1-SW1), (BOOST2-SW2) ................. 0.3V to 6V Lead Temperature (Soldering, 10 sec) + + SENSE1 , SENSE2 , SENSE1 , SENSE2 FE Package ....................................................... 300C V , V Voltages .................... 0.3V to 5.8V OSENSE1 OSENSE2 MODE/PLLIN, I , TK/SS1, TK/SS2, VID11, LIM VID12, VID21, VID22, FREQ Voltages ... 0.3V to INTV CC PIN CONFIGURATION LTC3865 LTC3865 TOP VIEW RUN1 1 38 FREQ + SENSE1 2 37 VID22 TOP VIEW SENSE 3 36 MODE/PLLIN NC 4 35 SW1 V 5 34 TG1 OSENSE1 TK/SS1 6 33 BOOST1 32 31 30 29 28 27 26 25 I 7 32 PGND1 V 1 24 BOOST1 TH1 OSENSE1 SGND 8 31 BG1 TK/SS1 BG1 2 23 VID11 9 30 V I 3 22 V IN TH1 IN 39 VID11 4 21 INTV VID12 10 29 INTV CC CC 33 SGND SGND VID12 5 20 EXTV I 11 28 EXTV CC CC TH2 I 6 19 BG2 TH2 TK/SS2 12 27 BG2 TK/SS2 PGND 7 18 V 13 26 PGND2 OSENSE2 V 8 17 BOOST2 OSENSE2 NC 14 25 BOOST2 9 10 11 12 13 14 15 16 SENSE2 15 24 NC + SENSE2 16 23 TG2 RUN2 17 22 SW2 UH PACKAGE VID21 18 21 PGOOD1 32-LEAD (5mm s 5mm) PLASTIC QFN I 19 20 PGOOD2 LIM T = 125C, = 34C/W, = 3C/W JMAX JA JC EXPOSED PAD (PIN 33) IS SGND, MUST BE SOLDERED TO PCB FE PACKAGE 38-LEAD PLASTIC TSSOP T = 125C, = 25C/W JMAX JA EXPOSED PAD (PIN 39) IS SGND, MUST BE SOLDERED TO PCB 3865fb 2 SENSE2 SENSE1 + + SENSE2 SENSE1 RUN2 RUN1 VID21 FREQ I VID22 LIM PGOOD MODE/PLLIN SW2 SW1 TG2 TG1