LTC3828 Dual, 2-Phase Step-Down Controller with Tracking FEATURES DESCRIPTION n Dual, 180 Phased Controllers Reduce Required The LTC 3828 is a dual high performance step-down Input Capacitance and Power Supply Induced Noise switching regulator controller that drives all N-channel n Tracking for Both Outputs synchronous power MOSFET stages. A constant frequency n Constant Frequency Current Mode Control current mode architecture allows for a phase-lockable n Wide V Range: 4.5V to 28V Operation frequency of up to 550kHz. The TRCKSS pin provides both IN n Power Good Output Voltage Indicator soft-start and tracking functions. Multiple LTC3828s can n Adjustable Soft-Start Current Ramping be daisy-chained in applications requiring more than two n Foldback Output Current Limiting voltages to be tracked. Disabled at Start-Up OPTI-LOOP compensation allows the transient response n No Reverse Current During Soft-Start Interval to be optimized over a wide range of output capacitance n Clock Output for 3-, 4-, 6-Phase Operation and ESR values. The precision 0.8V reference and power n Dual N-Channel MOSFET Synchronous Drive good output indicator are compatible with a wide 4.5V to n 1% Output Voltage Accuracy 28V (30V maximum) input supply range, encompassing n Phase-Lockable Fixed Frequency 260kHz to 550kHz all battery chemistries. n OPTI-LOOP Compensation Minimizes C OUT n The RUN pins control their respective channels indepen- Very Low Dropout Operation: 99% Duty Cycle n dently. The FCB/PLLIN pin selects among Burst Mode Output Overvoltage Protection n operation, skip-cycle mode and continuous current mode. Small 28-Lead SSOP and 5mm 5mm QFN Current foldback limits MOSFET dissipation during short- Packages circuit conditions. Reverse current and current foldback APPLICATIONS functions are disabled during soft-start. L, LT, LTC, LTM, Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology n Telecom Infrastructure Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, n ASIC Power Supply 6304066, 6580258 n Industry Equipment TYPICAL APPLICATION High Ef ciency Dual 2.5V/3.3V Step-Down Converter with Tracking 4.5V TO 28V 22F + 1F 50V 4.7F CERAMIC CERAMIC V PGOOD INTV IN CC TG1 TG2 0.1F 0.1F BOOST1 BOOST2 3.2H 3.2H SW1 SW2 LTC3828 BG1 BG2 500kHz FCB/PLLIN PGND + + SENSE1 SENSE2 1000pF 0.01 1000pF 0.01 SENSE1 SENSE2 2.5V 3.3V V V OSENSE1 OSENSE2 5A 5A 42.5k 63.4k 1% TRCKSS2 TRCKSS1 TRCKSS1 1% 63.4k 1% I I TH1 TH2 20k 20k 220pF 1% 220pF RUN1 RUN2 1% 20k SGND + 47F + 56F 1% 0.1F 4V 4V 15k 15k SP SP 3828 TA01 3828fc 1LTC3828 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) ........................ 30V to 0.3V PGOOD ...................................................... 5.5V to 0.3V IN Top Side Driver Voltages I , I , V , V Voltages ... 2.7V to 0.3V TH1 TH2 OSENSE1 OSENSE2 BOOST1, BOOST2 ................................. 36V to 0.3V Peak Output Current <10s (TG1, TG2, BG1, BG2) .... 3A Switch Voltage (SW1, SW2) ........................ 30V to 5V INTV Peak Output Current (Note 8) ................... 50mA CC INTV , DRV , RUN1, RUN2, (BOOST1-SW1), Operating Temperature Range (Note 7) CC CC (BOOST2-SW2) ........................................... 7V to 0.3V LTC3828E ............................................ 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 FCB/PLLIN, PLLFLTR, CLKOUT, Re ow Peak Body Temperature (UH Package) ..... 260C PHSMD Voltage .................................. INTV to 0.3V Lead Temperature (Soldering, 10 sec) CC TRCKSS1, TRCKSS2 ............................. INTV to 0.3V G Package .........................................................300C CC PIN CONFIGURATION TOP VIEW TOP VIEW 1 28 CLKOUT TRCKSS1 2 27 PGOOD I 32 31 30 29 28 27 26 25 TH1 3 26 BOOST1 SENSE1+ V 1 24 SW1 OSENSE1 4 25 TG1 SENSE1 PLLFLTR 2 23 V IN 5 24 SW1 V OSENSE1 RUN1 3 22 INTV CC 6 23 V PLLFLTR IN PHSMD 4 21 DRV CC 7 22 INTV RUN1 33 CC FCB/PLLIN 5 20 PGND 8 21 PGND FCB/PLLIN SGND 6 19 BG1 9 20 BG1 SGND TRCKSS2 7 18 BG2 10 19 BG2 TRCKSS2 11 18 SW2 NC 8 17 SW2 SENSE2 + 12 17 TG2 SENSE2 9 10 11 12 13 14 15 16 13 16 BOOST2 I TH2 14 15 RUN2 V OSENSE2 G PACKAGE UH PACKAGE 28-LEAD PLASTIC SSOP 32-LEAD (5mm s 5mm) PLASTIC QFN T = 125C, = 95C/W JMAX JA T = 125C, = 34C/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 LTC3828EG PBF LTC3828EG TRPBF LTC3828EG 28-Lead Plastic SSOP 40C to 85C LTC3828EUH PBF LTC3828EUH TRPBF 3828 32-Lead (5mm 5mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. 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