POWER LOSS (mW) LTC3827-1 Low I , Dual, 2-Phase Q Synchronous Step-Down Controller FEATURES DESCRIPTION n Wide Output Voltage Range: 0.8V V 10V The LTC 3827-1 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 quency of up to 650kHz. Power loss and noise due to the n OPTI-LOOP Compensation Minimizes C OUT ESR of the input capacitor ESR are minimized by operating n 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 LTC3827-1 features a precision 0.8V reference and a power Very Low Dropout Operation: 99% Duty Cycle n good output indicator. A wide 4V to 36V input supply range Adjustable Output Voltage Soft-Start or Tracking n encompasses all battery chemistries. Output Current Foldback Limiting 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 The PLLIN/MODE pin selects among Burst Mode opera- n Small 28-Lead SSOP Package tion, pulse-skipping mode, or continuous inductor cur- rent mode at light loads. For a leadless package version APPLICATIONS (5mm 5mm QFN) with additional features, see the n LTC3827 data sheet. Automotive Systems n L, LT, LTC, LTM, Burst Mode and OPTI-LOOP are registered trademarks of Linear Battery-Operated Digital Devices Technology Corporation. All other trademarks are the property of their respective owners. n Distributed DC Power Systems Protected by U.S. Patents including 5481178, 5929620, 6177787, 6144194, 5408150, 6580258, 6304066, 5705919. 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 LTC3827-1 PGND 40 POWER LOSS 10 + + 30 SENSE1 SENSE2 20 0.015 0.015 1 10 SENSE1 SENSE2 V V 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 38271 TA01b 20k 20k 15k 15k 0.1F FIGURE 13 CIRCUIT 0.1F 38271 TA01 38271fe 1 EFFICIENCY (%)LTC3827-1 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) TOP VIEW Input Supply Voltage (V ) .........................36V to 0.3V IN Topside Driver Voltages I 1 28 TRACK/SS1 TH1 V 2 27 PGOOD1 BOOST1, BOOST2 .................................. 42V to 0.3V FB1 + SENSE1 3 26 TG1 Switch Voltage (SW1, SW2) ......................... 36V to 5V SENSE1 4 25 SW1 (BOOST1-SW1), (BOOST2-SW2) ............. 8.5V to 0.3V PLLLPF 5 24 BOOST1 RUN1, RUN2 ............................................... 7V to 0.3V + + PLLIN/MODE 6 23 BG1 SENSE1 , SENSE2 , SENSE1 , SGND 7 22 V IN SENSE2 Voltages ..................................... 11V to 0.3V RUN1 8 21 PGND PLLIN/MODE, PLLLPF, TRACK/SS1, TRACK/SS2 RUN2 9 20 EXTV CC Voltages ............................................... INTV to 0.3V CC SENSE2 10 19 INTV CC EXTV ...................................................... 10V to 0.3V + CC SENSE2 11 18 BG2 I I , V , V Voltages .................. 2.7V to 0.3V TH1, TH2 FB1 FB2 V 12 17 BOOST2 FB2 PGOOD1 Voltage ....................................... 8.5V to 0.3V I 13 16 SW2 TH2 Peak Output Current <10s (TG1, TG2, BG1, BG2) .....3A TRACK/SS2 14 15 TG2 INTV Peak Output Current ................................. 50mA CC G PACKAGE 28-LEAD PLASTIC SSOP Operating Temperature Range (Note 2).... 40C to 85C T = 125C, = 95C/W JMAX JA Junction Temperature (Note 3) ............................. 125C Storage Temperature Range ................... 65C to 150C Lead Temperature (Soldering, 10 sec) .................. 300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3827EG-1 PBF LTC3827EG-1 TRPBF 3827EG-1 28-Lead Plastic SSOP 40C to 85C LTC3827IG-1 PBF LTC3827IG-1 TRPBF 3827IG-1 28-Lead Plastic SSOP 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3827EG-1 LTC3827EG-1 TR 3827EG-1 28-Lead Plastic SSOP 40C to 85C LTC3827IG-1 LTC3827IG-1 TR 3827IG-1 28-Lead Plastic SSOP 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. 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