LTC3707-SYNC High Ef ciency, 2-Phase Synchronous Step-Down Switching Regulator FEATURES DESCRIPTION n 180 Phased Controllers Reduce Required Input The LTC 3707-SYNC is a high performance dual step-down Capacitance and Power Supply Induced Noise switching regulator controller that drives all N-channel n OPTI-LOOP Compensation Minimizes C synchronous power MOSFET stages. A constant frequency OUT n Dual N-Channel MOSFET Synchronous Drive current mode architecture allows phase-lockable frequency n 1.5% Output Voltage Accuracy of up to 300kHz. Power loss and noise due to the ESR of n Power Good Output Voltage Monitor the input capacitors are minimized by operating the two n Phase-Lockable Fixed Frequency 150kHz to 300kHz controller output stages out of phase. n Wide V Range: 4.5V to 28V Operation IN OPTI-LOOP compensation allows the transient response to n Very Low Dropout Operation: 99% Duty Cycle be optimized over a wide range of output capacitance and n Adjustable Soft-Start Current Ramping ESR values. The precision 0.8V reference and power good n Foldback Output Current Limiting output indicator are compatible with future microprocessor n Latched Short-Circuit Shutdown with Defeat Option generations, and a wide 4.5V to 28V (30V maximum) input n Output Overvoltage Protection supply range encompasses all battery chemistries. n Remote Output Voltage Sense n A RUN/SS pin for each controller provides both soft- Low Shutdown I : 20A Q n start and optional timed, short-circuit shutdown. Current 5V and 3.3V Standby Regulators n foldback limits MOSFET dissipation during short-circuit Small 28-Lead Narrow SSOP Package (0.150 Wide) n conditions when overcurrent latchoff is disabled. Output Selectable Constant Frequency, Burst Mode or overvoltage protection circuitry latches on the bottom PWM Operation MOSFET until V returns to normal. The FCB mode OUT APPLICATIONS pin can select among Burst Mode operation, constant frequency mode and continuous inductor current mode n Notebook and Palmtop Computers, PDAs or regulate a secondary winding. The IC includes a power n Telecom Systems good output pin that indicates when both outputs are within n Portable Instruments 7.5% of their designed set point. n Battery-Operated Digital Devices L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode n and OPTI-LOOP are registered trademarks of Linear Technology Corporation. Protected by U.S. DC Power Distribution Systems Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6304066, 6580258. V IN 5.2V TO 28V C IN + TYPICAL APPLICATION 1F 22F 4.7F D3 CERAMIC D4 50V V PGOOD INTV IN CC CERAMIC M1 TG1 TG2 M3 L1 C , 0.1F L2 B2 6.3H BOOST1 BOOST2 6.3H C , 0.1F B1 SW1 SW2 LTC3707-SYNC M2 BG1 BG2 M4 D1 D2 f PLLIN PGND IN + + SENSE1 SENSE2 R R SENSE1 1000pF SENSE2 1000pF 0.01 0.01 SENSE1 SENSE2 V V OUT1 OUT2 V V 3.3V 5V OSENSE1 OSENSE2 5A R2 R4 5A I I 105k TH1 TH2 63.4k C C C C1 C2 C OUT1 1% 1% OUT + RUN/SS1 SGND RUN/SS2 R1 R3 220pF 220pF 47F 56mF 20k 20k R R 6V C1 C C C2 6V SS1 SS2 1% 1% SP 15k 15k 0.1F 0.1F SP M1, M2, M3, M4: FDS6680A 3707 F01 Figure 1. High Ef ciency Dual 5V/3.3V Step-Down Converter 3707sfa 1 +LTC3707-SYNC ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Input Supply Voltage (V ) ......................... 30V to 0.3V IN RUN/SS1 1 28 PGOOD Top Side Driver Voltages + SENSE1 2 27 TG1 (BOOST1, BOOST2) ................................... 36V to 0.3V SENSE1 3 26 SW1 Switch Voltage (SW1, SW2) ......................... 30V to 5V V 4 25 BOOST1 OSENSE1 INTV , EXTV , RUN/SS1, RUN/SS2, (BOOST1-SW1), CC CC PLLFLTR 5 24 V IN (BOOST2-SW2), PGOOD .............................. 7V to 0.3V PLLIN 6 23 BG1 + + SENSE1 , SENSE2 , SENSE1 , FCB 7 22 EXTV CC SENSE2 Voltages .........................(1.1)INTV to 0.3V CC I 8 21 INTV CC TH1 PLLIN, PLLFLTR, FCB, Voltage ............. INTV to 0.3V SGND 9 20 PGND CC I , I , V , V Voltages ... 2.7V to 0.3V 3.3V 10 19 BG2 TH1 TH2 OSENSE1 OSENSE2 OUT I 11 18 BOOST2 Peak Output Current <10s (TG1, TG2, BG1, BG2) .....3A TH2 V 12 17 SW2 INTV Peak Output Current ................................. 40mA OSENSE2 CC SENSE2 13 16 TG2 Operating Temperature Range (Note 2).... 40C to 85C + SENSE2 14 15 RUN/SS2 Junction Temperature (Note 3) ............................. 125C Storage Temperature Range ................... 65C to 150C GN PACKAGE 28-LEAD PLASTIC SSOP Lead Temperature (Soldering, 10 sec) .................. 300C T = 125C, = 80C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3707EGN-SYNC PBF LTC3707EGN-SYNC TRPBF LTC3707EGN-SYNC 28-Lead Plastic SSOP 40C to 85C LTC3707IGN-SYNC PBF LTC3707IGN-SYNC TRPBF LTC3707IGN-SYNC 28-Lead Plastic SSOP 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3707EGN-SYNC LTC3707EGN-SYNC TR LTC3707EGN-SYNC 28-Lead Plastic SSOP 40C to 85C LTC3707IGN-SYNC LTC3707IGN-SYNC TR LTC3707IGN-SYNC 28-Lead Plastic SSOP 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. 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