POWER LOSS (mW) LTC3835 Low I Synchronous Q Step-Down Controller FEATURES DESCRIPTION n Wide Output Voltage Range: 0.8V V 10V The LTC 3835 is a high performance step-down switching OUT n Low Operating Quiescent Current: 80A regulator controller that drives an all N-channel synchro- n OPTI-LOOP Compensation Minimizes C nous power MOSFET stage. A constant-frequency current OUT n 1% Output Voltage Accuracy mode architecture allows a phase-lockable frequency of n Wide V Range: 4V to 36V Operation up to 650kHz. IN n Phase-Lockable Fixed Frequency 140kHz to 650kHz The 80A no-load quiescent current extends operating n Dual N-Channel MOSFET Synchronous Drive life in battery powered systems. OPTI-LOOP compensa- n Very Low Dropout Operation: 99% Duty Cycle tion allows the transient response to be optimized over n Adjustable Output Voltage Soft-Start or Tracking a wide range of output capacitance and ESR values. The n Output Current Foldback Limiting LTC3835 features a precision 0.8V reference and a power n Power Good Output Voltage Monitor good output indicator. The 4V to 36V input supply range n Clock Output for PolyPhase Applications encompasses a wide range of battery chemistries. n Output Overvoltage Protection n The TRACK/SS pin ramps the output voltage during start- Low Shutdown I : 10A Q n up. Current foldback limits MOSFET heat dissipation dur- Internal LDO Powers Gate Drive from V or V IN OUT n ing short-circuit conditions. Selectable Continuous, Pulse-Skipping or n Burst Mode Operation at Light Loads Comparison of LTC3835 and LTC3835-1 n Small 20-Lead TSSOP or 4mm 5mm QFN Package CLKOUT/ n AEC-Q100 Qualified for Automotive Applications PART PHASMD EXTV PGOOD PACKAGES CC LTC3835 YES YES YES FE20/4 5 QFN APPLICATIONS LTC3835-1 NO NO NO GN16/3 5 DFN n Automotive Systems All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 5408150, 5481178, 5705919, 5929620, 6304066, 6498466, n Telecom Systems 6580258, 6611131. n Battery-Operated Digital Devices n Distributed DC Power Systems TYPICAL APPLICATION Efficiency and Power Loss High Efficiency Synchronous Step-Down Converter vs Load Current CLKOUT V 100000 IN V 100 IN PLLLPF 4V TO EFFICIENCY 10F 90 TG 36V RUN V = 12V V = 3.3V IN OUT 10000 0.01F 0.22F 80 PGOOD TRACK/SS BOOST 70 3.3H 0.012 V 1000 OUT I TH SW 3.3V 60 330pF LTC3835 5A 50 100 100pF 33k 150F 40 SGND INTV CC POWER LOSS 10 30 4.7F 20k PLLIN/MODE EXTV CC 20 V BG FB 1 10 SENSE 62.5k + 0 0.1 SENSE PGND 0.001 0.01 0.1 1 10 100 1000 10000 LOAD CURRENT (mA) 3835 TA01b 3835 TA01 Rev. F 1 Document Feedback For more information www.analog.com EFFICIENCY (%)LTC3835 (Note 1) ABSOLUTE MAXIMUM RATINGS Input Supply Voltage (V ) ......................... 36V to 0.3V Peak Output Current <10s (TG,BG) ...........................3A IN Top Side Driver Voltage (BOOST) ............... 42V to 0.3V INTV Peak Output Current ................................. 50mA CC Switch Voltage (SW) ..................................... 36V to 5V Operating Temperature Range (Note 2)....40C to 85C INTV , (BOOST-SW), CLKOUT, PGOOD .. 8.5V to 0.3V Junction Temperature (Note 3) ............................. 125C CC RUN, TRACK/SS ........................................ 7V to 0.3V Storage Temperature Range + SENSE , SENSE Voltages .........................11V to 0.3V FE Package ........................................ 65C to 150C PLLIN/MODE, PHASMD, PLLLPF .........INTV to 0.3V Storage Temperature Range CC EXTV ..................................................... 10V to 0.3V UFD Package .................................... 65C to 125C CC I , V Voltages ...................................... 2.7V to 0.3V Lead Temperature (FE Package, Soldering, 10 sec) ... 300C TH FB PIN CONFIGURATION TOP VIEW TOP VIEW 1 CLKOUT 20 PHASMD 2 PLLLPF 19 PLLIN/MODE 20 19 18 17 3 I 18 PGOOD TH I 1 16 PGOOD + TH 4 TRACKS/SS 17 SENSE + TRACK/SS 2 15 SENSE 5 V 21 16 SENSE FB V SENSE 3 14 FB SGND 21 6 SGND 15 RUN SGND SGND 4 13 RUN 7 PGND 14 BOOST PGND 5 12 BOOST 8 BG 13 TG BG 6 11 TG 9 INTV 12 SW CC 7 8 9 10 10 EXTV 11 V CC IN FE PACKAGE 20-LEAD PLASTIC TSSOP UFD PACKAGE 20-PIN (4mm 5mm) PLASTIC QFN T = 125C, = 35C/W JMAX JA EXPOSED PAD (PIN 21) IS SGND MUST BE SOLDERED TO PCB T = 125C, = 37C/W JMAX JA EXPOSED PAD (PIN 21) IS SGND MUST BE SOLDERED TO PCB Rev. F 2 For more information www.analog.com PLLLPF INTV CC EXTV CLKOUT CC V PHASMD IN SW PLLIN/MODE