LTC3728L-1 Dual, 550kHz, 2-Phase Synchronous Regulator FEATURES DESCRIPTION n Dual, 180 Phased Controllers Reduce Required The LTC 3728L-1 is a dual high performance step-down Input 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 current mode architecture allows phase-lockable frequency 1.5% Output Voltage Accuracy of up to 550kHz. Power loss and noise due to the ESR of n Power Good Output Voltage Indicator the input capacitors are minimized by operating the two n Phase-Lockable Fixed Frequency 250kHz to 550kHz controller output stages out of phase. The LTC3728L-1 n Over Current Latchoff Disabled is identical to the LTC3728L except that the LTC3728L-1 n Wide V Range: 4.5V to 28V (35V for LTC3728LI-1) IN lacks the over current latchoff feature. Operation n OPTI-LOOP compensation allows the transient response to Very Low Dropout Operation: 99% Duty Cycle n be optimized over a wide range of output capacitance and 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 microproces- n Output Overvoltage Protection sor generations, and a wide 4.5V to 28V (30V maximum/ n Low Shutdown I : 20A Q 35V for LTC3728LI-1) input supply range encompasses n 5V and 3.3V Standby Regulators all battery chemistries. n 3 Selectable Operating Modes: Constant Frequency, A RUN/SS pin for each controller provides soft-start. Burst Mode Operation and PWM Current foldback limits MOSFET dissipation during short- n 5mm 5mm QFN and 28-Lead Narrow SSOP circuit conditions. The FCB mode pin can select among Packages Burst Mode operation, constant frequency mode and continuous inductor current mode or regulate a secondary APPLICATIONS winding. The LTC3728L-1 includes a power good output n Notebook and Palmtop Computers pin that indicates when both outputs are within 7.5% of n Telecom Systems their designed set point. n Portable Instruments L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation. Battery-Operated Digital Devices All other trademarks are the property of their respective owners. n DC Power Distribution Systems Protected by U.S. Patents including 5929620, 6177787, 6144199, 5471178, 5994885, 6100678. TYPICAL APPLICATION V IN 5.2V TO 28V C 1F IN + 22F 4.7F CERAMIC D3 D4 50V V PGOOD INTV IN CC M2 M1 CERAMIC TG1 TG2 L1 L2 BOOST1 BOOST2 3.2H 3.2H C , 0.1F B1 C , 0.1F B2 SW1 SW2 LTC3728L-1 BG1 BG2 f IN PLLIN PGND 500kHz + + SENSE1 SENSE2 R R SENSE2 SENSE1 1000pF 1000pF 0.01 0.01 SENSE1 SENSE2 V V V V OSENSE1 OSENSE2 OUT1 OUT2 R2 R4 5V I I 3.3V TH1 TH2 C C 63.4k 105k 5A 5A C1 C2 C C OUT1 RUN/SS1 SGND RUN/SS2 OUT + 1% 220pF 220pF 1% R1 R3 47F 56F 20k R R 20k C1 C C C2 SS1 SS2 6V 6V 1% 15k 15k 1% 0.1F 0.1F SP SP M1, M2: FDS6982S 3728l1 F01 Figure 1. High Ef ciency Dual 5V/3.3V Step-Down Converter 3728l1fc 1 +LTC3728L-1 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) .........................30V to 0.3V PLLIN, PLLFLTR, FCB, Voltage .............. INTV to 0.3V IN CC Input Supply Voltage (V ) LTC3728LI-1 ....35V to 0.3V I I , V , V Voltages .... 2.7V to 0.3V IN TH1, TH2 OSENSE1 OSENSE2 Top Side Driver Voltages Peak Output Current <10s (TG1, TG2, BG1, BG2) .....3A (BOOST1, BOOST2) ............................... 36V to 0.3V INTV Peak Output Current ..................................40mA CC (BOOST1, BOOST2) LTC3728LI-1 .......... 38V to 0.3V Operating Temperature Range (Note 7).... 40C to 85C Switch Voltage (SW1, SW2) ...........................30V to 5V Junction Temperature (Note 2) ............................. 125C Switch Voltage (SW1, SW2) LTC3728LI-1 ...35V to 0.3V Storage Temperature Range ................... 65C to 125C INTV EXTV , RUN/SS1, RUN/SS2, (BOOST1-SW1), Re ow Peak Body Temperature (UH Package) ...... 260C CC, CC (BOOST2-SW2), PGOOD ......................... 7V to 0.3V Lead Temperature (Soldering, 10 sec) INTV EXTV LTC3728LI-1 ....................... 8V to 0.3V GN Package ...................................................... 300C CC, CC + + SENSE1 , SENSE2 , SENSE1 , SENSE2 Voltages .....................(1.1)INTV to 0.3V CC PIN CONFIGURATION TOP VIEW TOP VIEW 1 PGOOD RUN/SS1 28 + 2 27 TG1 SENSE1 32 31 30 29 28 27 26 25 SENSE 3 26 SW1 V 1 24 BOOST1 OSENSE1 V 4 25 BOOST1 OSENSE1 PLLFLTR 2 23 V IN 5 24 V PLLFLTR IN PLLIN BG1 3 22 PLLIN 6 23 BG1 FCB EXTV 4 21 CC FCB 7 22 EXTV 33 CC I INTV 5 20 TH1 CC 8 INTV I 21 TH1 CC SGND PGND 6 19 9 20 PGND SGND 3.3V 7 18 BG2 OUT 3.3V 10 19 BG2 OUT I 8 17 BOOST2 TH2 11 BOOST2 I 18 TH2 9 10 11 12 13 14 15 16 12 17 SW2 V OSENSE2 SENSE2 13 16 TG2 + SENSE2 14 15 RUN/SS2 UH PACKAGE GN PACKAGE 32-LEAD (5mm s 5mm) PLASTIC QFN 28-LEAD NARROW PLASTIC SSOP T = 125C, = 34C/W JMAX JA T = 125C, = 95C/W JMAX JA EXPOSED PAD (PIN 33) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3728LEGN-1 PBF LTC3728LEGN-1 TRPBF LTC3728LEGN-1 28-Lead Narrow Plastic SSOP 40C to 85C LTC3728LIGN-1 PBF LTC3728LIGN-1 TRPBF LTC3728LIGN-1 28-Lead Narrow Plastic SSOP 40C to 85C LTC3728LEUH-1 PBF LTC3728LEUH-1 TRPBF 728LE1 40C to 85C 32-Lead (5mm 5mm) Plastic DFN LTC3728LIUH-1 PBF LTC3728LIUH-1 TRPBF 3728L1 32-Lead (5mm 5mm) Plastic DFN 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3728LEGN-1 LTC3728LEGN-1 TR LTC3728LEGN-1 28-Lead Narrow Plastic SSOP 40C to 85C LTC3728LIGN-1 LTC3728LIGN-1 TR LTC3728LIGN-1 28-Lead Narrow Plastic SSOP 40C to 85C LTC3728LEUH-1 LTC3728LEUH-1 TR 728LE1 32-Lead (5mm 5mm) Plastic DFN 40C to 85C LTC3728LIUH-1 LTC3728LIUH-1 TR 3728L1 32-Lead (5mm 5mm) Plastic DFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. 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