LTC3728L/LTC3728LX Dual, 550kHz, 2-Phase Synchronous Regulators Fea T Descrip T n Dual, 180 Phased Controllers Reduce Required The LTC 3728L/LTC3728LX are dual high performance Input Capacitance and Power Supply Induced Noise step-down switching regulator controllers that drive all n OPTI-LOOP Compensation Minimizes C N-channel synchronous power MOSFET stages. A constant- OUT n 1% Output Voltage Accuracy (LTC3728LC) frequency, current mode architecture allows phase-lockable n frequency of up to 550kHz. Power loss and noise due to Power Good Output Voltage Indicator n Phase-Lockable Fixed Frequency 250kHz to 550kHz the ESR of the input capacitors are minimized by operating n the two controller output stages out of phase. Dual N-Channel MOSFET Synchronous Drive 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 microproces- n Latched Short-Circuit Shutdown with Defeat Option sor generations, and a wide 4.5V to 28V (30V maximum) n Output Overvoltage Protection input supply range encompasses all battery chemistries. n Low Shutdown I : 20A Q A RUN/SS pin for each controller provides both soft- n 5V and 3.3V Standby Regulators start and optional timed, short-circuit shutdown. Current n 3 Selectable Operating Modes: Constant-Frequency, foldback limits MOSFET dissipation during short-circuit Burst Mode Operation and PWM conditions when overcurrent latchoff is disabled. Output n 5mm 5mm QFN and 28-Lead Narrow SSOP overvoltage protection circuitry latches on the bottom Packages MOSFET until V returns to normal. The FCB mode OUT pin can select among Burst Mode, constant-frequency a T mode and continuous inductor current mode or regulate n Notebook and Palmtop Computers a secondary winding. The LTC3728L/LTC3728LX include n Telecom Systems a power good output pin that indicates when both outputs n Portable Instruments are within 7.5% of their designed set point. n Battery-Operated Digital Devices L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, OPTI-LOOP and PolyPhase n DC Power Distribution Systems are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical a T V IN 5.2V TO 28V C IN + 1F 22F 4.7F CERAMIC D3 D4 50V V PGOOD INTV IN CC CERAMIC M1 M2 TG1 TG2 L1 L2 BOOST1 BOOST2 3.2H 3.2H C , 0.1F C , 0.1F B1 B2 SW1 SW2 LTC3728L/ BG1 BG2 LTC3728LX D1 D2 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 3.3V 5V I I TH1 TH2 105k 63.4k 5A 5A C C C1 C2 C OUT1 RUN/SS1 SGND RUN/SS2 C 1% 1% OUT 220pF 220pF + 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 3728 F01 Figure 1. High Efficiency Dual 5V/3.3V Step-Down Converter 3728lxff 1 + ion pplica ions pplica ion uresLTC3728L/LTC3728LX a Te Maxi Mu M r a T (Note 1) Input Supply Voltage (V ) ........................ 30V to 0.3V I I , V , V Voltages ... 2.7V to 0.3V IN TH1, TH2 OSENSE1 OSENSE2 Topside Driver Voltages Peak Output Current <10s (TG1, TG2, BG1, BG2) .... 3A (BOOST1, BOOST2) .............................. 36V to 0.3V INTV Peak Output Current ................................. 40mA CC Switch Voltage (SW1, SW2) ........................ 30V to 5V Operating Temperature Range (Note 7) INTV EXTV , RUN/SS1, RUN/SS2, LTC3728LC/LTC3728LXC ........................ 0C to 85C CC, CC (BOOST1-SW1), (BOOST2-SW2), PGOOD .... 7V to 0.3V LTC3728LE/LTC3728LI ........................ 40C to 85C + + SENSE1 , SENSE2 , SENSE1 , Junction Temperature (Note 2) ............................ 125C SENSE2 Voltages ........................ (1.1)INTV to 0.3V Storage Temperature Range .................. 65C to 125C CC PLLIN, PLLFLTR, FCB Voltages ............ INTV to 0.3V Reflow Peak Body T emperature (UH Package) ..... 260C CC Lead Temperature (Soldering, 10 sec) (GN Package) ....................................................300C p in c F T TOP VIEW TOP VIEW RUN/SS1 1 28 PGOOD + SENSE1 2 27 TG1 32 31 30 29 28 27 26 25 SENSE1 3 26 SW1 V 1 24 BOOST1 OSENSE1 V 4 25 BOOST1 OSENSE1 PLLFLTR 2 23 V IN PLLFLTR 5 24 V IN PLLIN BG1 3 22 PLLIN 6 23 BG1 FCB 4 21 EXTV CC FCB 7 22 EXTV 33 CC I 5 20 INTV TH1 CC I 8 21 INTV CC TH1 SGND 6 19 PGND SGND 9 20 PGND 3.3V 7 18 BG2 OUT 3.3V 10 19 BG2 OUT I BOOST2 8 17 TH2 I 11 18 BOOST2 TH2 9 10 11 12 13 14 15 16 V 12 17 SW2 OSENSE2 SENSE2 13 16 TG2 + SENSE2 14 15 RUN/SS2 UH PACKAGE GN PACKAGE 32-LEAD (5mm 5mm) PLASTIC QFN 28-LEAD NARROW PLASTIC SSOP T = 125C, = 34C/W JMAX JA T = 125C, = 95C/W EXPOSED PAD IS SGND (PIN 33), MUST BE SOLDERED TO PCB JMAX JA 3728lxff 2 V NC OSENSE2 NC SENSE1 + SENSE2 SENSE1 + SENSE2 NC RUN/SS2 RUN/SS1 TG2 PGOOD SW2 TG1 NC SW1 ion igura on ings bsolu