LTC3729 550kHz, PolyPhase, High Efficiency, Synchronous Step-Down Switching Regulator FEATURES DESCRIPTION n Wide V Range: 4V to 36V Operation The LTC 3729 is a multiple phase, synchronous IN n Reduces Required Input Capacitance and Power stepdown current mode switching regulator controller Supply Induced Noise that drives Nchannel external power MOSFET stages in a n 1% Output Voltage Accuracy phaselockable fixed frequency architecture. The PolyPhase n Phase-Lockable Fixed Frequency: 250kHz to 550kHz controller drives its two output stages out of phase at n True Remote Sensing Differential Amplifier frequencies up to 550kHz to minimize the RMS ripple n PolyPhase Extends from Two to Twelve Phases currents in both input and output capacitors. The output n Reduces the Size and Value of Inductors clock signal allows expansion for up to 12 evenly phased n Current Mode Control Ensures Current Sharing controllers for systems requiring 15A to 200A of output n 1.1MHz Effective Switching Frequency (2 Phase) current. The multiple phase technique effectively multiplies n OPTI LOOP Compensation Reduces C the fundamental frequency by the number of channels OUT n Power Good Output Voltage Indicator used, improving transient response while operating each n Very Low Dropout Operation: 99% Duty Cycle channel at an optimum frequency for efficiency. Thermal n Adjustable Soft Start Current Ramping design is also simplified. n Internal Current Foldback Plus Shutdown Timer An internal differential amplifier provides true remote sens n Overvoltage Soft Latch Eliminates Nuisance Trips ing of the regulated supplys positive and negative output n Available in 5mm 5mm QFN terminals as required for high current applications. and 28 Lead SSOP Packages A RUN/SS pin provides both soft start and optional timed, APPLICATIONS short circuit shutdown. Current foldback limits MOSFET dissipation during short circuit conditions when the n Desktop Computers/Servers overcurrent latchoff is disabled. OPTI LOOP compensation n Large Memory Arrays allows the transient response to be optimized over a wide n DC Power Distribution Systems range of output capacitance and ESR values. The LTC3729 L, LT, LTC, LTM, PolyPhase, OPTI LOOP, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their includes a power good output pin that indicates when the respective owners. output is within 7.5% of the designed set point. TYPICAL APPLICATION V IN 0.1F 5V TO 28V 10 10F M1 LTC3729 V TG1 IN 35V 0.002 BOOST1 CERAMIC 0.47F 0.1F 4 SW1 L1 M2 D1 RUN/SS 0.8H BG1 2 PGND PGOOD + SENSE1 I TH SENSE1 3.3k 1000pF M3 TG2 0.002 SGND BOOST2 V OUT 0.47F 1.6V/40A L2 SW2 16k M4 0.8H V BG2 DIFFOUT 2 D2 EAIN INTV CC 10F + C + OUT V SENSE2 OS 16k 1000F 2 + V SENSE2 OS 4V C : T510E108K004AS L1, L2: CEPH149-IROMC M1, M3: IRF7811W OUT 3729 TA01 D1, D2: UP5840 M2, M4: IRF7822 Figure 1. High Current Dual Phase Step-Down Converter 3729fb 1 + S S S S S S S S SLTC3729 (Note 1) ABSOLUTE MAXIMUM RATINGS Input Supply Voltage (V ) ......................... 36V to 0.3V V Voltages .............V 2V to 0.3V for V < 7V IN DIFFOUT IN IN Topside Driver Voltages (BOOST1,2) ......... 42V to 0.3V I Voltage ............................................... 2.7V to 0.3V TH Switch Voltage (SW1, 2) .............................. 36V to 5 V Peak Output Current <1s(TGL1,2, BG1,2) .................5A + + SENSE1 , SENSE2 , SENSE1 , INTV RMS Output Current ................................. 50mA CC SENSE2 Voltages .........................(1.1)INTV to 0.3V Operating Ambient Temperature CC + EAIN, V , V , EXTV , INTV , Range (Note 6) ......................................... 40C to 85C OS OS CC CC RUN/SS, PGOOD Voltages .......................... 7V to 0.3V Junction Temperature (Note 2) ............................. 125C Boosted Driver Voltage (BOOST SW) ........... 7V to 0.3V Storage Temperature Range ................... 65C to 150C PLLFLTR, PLLIN, CLKOUT, PHASMD, Lead Temperature (Soldering, 10 sec) V Voltages ..............INTV to 0.3V for V 7V (G Package Only) .............................................. 300C DIFFOUT CC IN PIN CONFIGURATION TOP VIEW TOP VIEW 1 CLKOUT RUN/SS 28 + 2 TG1 SENSE1 27 3 SW1 32 31 30 29 28 27 26 25 SENSE1 26 EAIN 1 24 BOOST1 4 BOOST1 EAIN 25 PLLFLTR 2 23 V 5 V IN PLLFLTR 24 IN PLLIN BG1 3 22 6 BG1 PLLIN 23 PHASMD 4 21 EXTV CC 7 EXTV PHASMD 22 CC I 5 20 INTV TH CC 8 INTV I 21 TH CC SGND 6 19 PGND 9 PGND SGND 20 V 7 18 BG2 DIFFOUT 10 BG2 V 19 DIFFOUT V 8 17 BOOST2 OS 11 BOOST2 V 18 OS 9 10 11 12 13 14 15 16 + 12 SW2 V 17 OS 13 TG2 SENSE2 16 + 14 PGOOD SENSE2 15 UH PACKAGE G PACKAGE 32-LEAD 5mm 5mm PLASTIC QFN 28-LEAD PLASTIC SSOP = 34C/W JA T = 125C, = 95C/W EXPOSED PAD IS GND, MUST BE SOLDERED TO PCB JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3729EG PBF LTC3729EG TRPBF LTC3729 28 Lead Plastic SSOP 40C to 85C LTC3729EUH PBF LTC3729EUH TRPBF 3729 32 Lead (5mm 5mm)Plastic QFN 40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non standard lead based finish parts. For more information on lead free part marking, go to: