POWER LOSS (mW) LTC3827 Low I , Dual, 2-Phase Q Synchronous Step-Down Controller FEATURES DESCRIPTION n Wide Output Voltage Range: 0.8V V 10V The LTC 3827 is a high performance dual step-down OUT n switching regulator controller that drives all N-channel Low Operating I : 80A (One Channel On) Q n synchronous power MOSFET stages. A constant frequency Out-of-Phase Controllers Reduce Required Input current mode architecture allows a phase-lockable fre- Capacitance and Power Supply Induced Noise n quency of up to 650kHz. Power loss and noise due to the OPTI-LOOP Compensation Minimizes C OUT n ESR of the input capacitor ESR are minimized by operating 1% Output Voltage Accuracy the two controller output stages out of phase. n Wide V Range: 4V to 36V Operation IN n Phase-Lockable Fixed Frequency 140kHz to 650kHz The 80A no-load quiescent current extends operating n Selectable Continuous, Pulse Skipping or Low Ripple life in battery-powered systems. OPTI-LOOP compensa- Burst Mode Operation at Light Loads tion allows the transient response to be optimized over n Dual N-Channel MOSFET Synchronous Drive a wide range of output capacitance and ESR values. The n Very Low Dropout Operation: 99% Duty Cycle LTC3827 features a precision 0.8V reference and a power n Adjustable Output Voltage Soft-Start or Tracking good output indicator. A wide 4V to 36V input supply range n Output Current Foldback Limiting encompasses all battery chemistries. n Power Good Output Voltage Monitor Independent TRACK/SS pins for each controller ramp the n Output Overvoltage Protection output voltage during start-up. Current foldback limits n Low Shutdown I : 8A Q MOSFET heat dissipation during short-circuit conditions. n Internal LDO Powers Gate Drive from V or V IN OUT n The PLLIN/MODE pin selects among Burst Mode opera- Small 5mm 5mm QFN Package tion, pulse skipping mode, or continuous inductor cur- rent mode at light loads. For a leaded package version APPLICATIONS (28-lead SSOP), see the LTC3827-1 datasheet. n Automotive Systems 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. Protected by U.S. Patents n Distributed DC Power Systems including 5481178, 5929620, 6177787, 6144194, 5408150, 6580258, 6304066, 570919. TYPICAL APPLICATION High Ef ciency Dual 8.5V/3.3V Step-Down Converter Ef ciency and Power Loss V IN vs Load Current 4V TO 36V + 22F 100000 100 1F 4.7F 50V EFFICIENCY V INTV IN CC 90 V = 12V V = 3.3V IN OUT TG1 TG2 10000 80 0.1F BOOST1 BOOST2 70 3.3H 7.2H 0.1F 1000 SW1 SW2 60 BG1 BG2 50 100 LTC3827 PGND 40 POWER LOSS 10 + + 30 SENSE1 SENSE2 20 0.015 0.015 1 10 SENSE1 SENSE2 V V FIGURE 13 CIRCUIT OUT1 OUT2 0 0.1 3.3V V V 8.5V FB1 FB2 0.001 0.01 0.1 1 10 100 1000 10000 5A 62.5k 192.5k 3.5A I I TH1 TH2 LOAD CURRENT (mA) 220pF 220pF 150F 150F TRACK/SS1 SGND TRACK/SS2 3827 TA01b 20k 20k 15k 15k 0.1F 0.1F 3827 TA01 3827ff 1 EFFICIENCY (%)LTC3827 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Input Supply Voltage (V ) .........................36V to 0.3V IN Topside Driver Voltages BOOST1, BOOST2 .................................. 42V to 0.3V 32 31 30 29 28 27 26 25 Switch Voltage (SW1, SW2) ......................... 36V to 5V SENSE1 1 24 BOOST1 BOOST1-SW1, BOOST2-SW2 .................. 8.5V to 0.3V PLLLPF 2 23 BG1 RUN1, RUN2 ............................................... 7V to 0.3V PHASMD 3 22 V IN + + CLKOUT 4 21 PGND SENSE1 , SENSE2 , SENSE1 , 33 PLLIN/MODE 5 20 EXTV CC SENSE2 Voltages .................................... 11V to 0.3V SGND 6 19 INTV CC PLLIN/MODE, PLLLPF, Voltages ........... INTV to 0.3V CC RUN1 7 18 BG2 RUN2 8 17 BOOST2 PHASMD, FOLDDIS, TRACK/SS1, TRACK/SS2 9 10 11 12 13 14 15 16 Voltages ............................................... INTV to 0.3V CC EXTV ...................................................... 10V to 0.3V CC I I , V , V Voltages .................. 2.7V to 0.3V TH1, TH2 FB1 FB2 UH PACKAGE PGOOD1, PGOOD2 Voltages ..................... 8.5V to 0.3V 32-LEAD (5mm 5mm) PLASTIC QFN T = 125C, = 34C/W Peak Output Current <10s (TG1, TG2, BG1, BG2) .....3A JMAX JA EXPOSED PAD (PIN 33) IS SGND INTV Peak Output Current ................................. 50mA CC MUST BE SOLDERED TO PCB Operating Temperature Range (Note 2).... 40C to 85C Junction Temperature (Note 3) ............................. 125C Storage Temperature Range .................. 65C to 125C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3827EUH PBF LTC3827EUH TRPBF 3827 32-Lead (5mm 5mm) Plastic QFN 40C to 85C LTC3827IUH PBF LTC3827IUH TRPBF 3827 32-Lead (5mm 5mm) Plastic QFN 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3827EUH LTC3827EUH TR 3827 32-Lead (5mm 5mm) Plastic QFN 40C to 85C LTC3827IUH LTC3827IUH TR 3827 32-Lead (5mm 5mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. 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