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LTC3854 Dataheets PDF



Part Number LTC3854
Manufacturers Linear Technology Corporation
Logo Linear Technology Corporation
Description Wide Vin Range Synchronous Step-Down DC/DC Controller
Datasheet LTC3854 DatasheetLTC3854 Datasheet (PDF)

www.DataSheet4U.com FEATURES n n n n n n n n n n n n n n LTC3854 Small Footprint, Wide VIN Range Synchronous Step-Down Controller DESCRIPTION The LTC3854® is a high performance synchronous stepdown switching regulator controller that drives an all N-channel synchronous power MOSFET stage. The LTC3854 features a 400kHz constant frequency current mode architecture. The LTC3854 operates from a 4.5V to 38V (40V absolute maximum) input voltage range and regulates the output voltage from 0.8V to 5.5.

  LTC3854   LTC3854


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www.DataSheet4U.com FEATURES n n n n n n n n n n n n n n LTC3854 Small Footprint, Wide VIN Range Synchronous Step-Down Controller DESCRIPTION The LTC3854® is a high performance synchronous stepdown switching regulator controller that drives an all N-channel synchronous power MOSFET stage. The LTC3854 features a 400kHz constant frequency current mode architecture. The LTC3854 operates from a 4.5V to 38V (40V absolute maximum) input voltage range and regulates the output voltage from 0.8V to 5.5V. The RUN/SS pin provides both soft-start and enable features. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. Current foldback limits MOSFET dissipation during short circuit conditions. Current foldback functions are disabled during soft-start. The LTC3854 has a minimum on-time at 75ns, making it well suited for high step-down ratios. The strong onboard MOSFET drivers allow the use of high power external MOSFETs to produce output currents up to 20A. L, LT, LTC, LTM, Linear Technology, the Linear logo and OPTI-LOOP are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5705919, 6498466, 5408150, 6222231. Wide Operating VIN Range: 4.5V to 38V RSENSE or DCR Current Sensing ±1% 0.8V Reference Accuracy Over Temperature 400kHz Switching Frequency Dual N-channel MOSFET Synchronous Drive Very Low Dropout Operation: 97% Duty Cycle Starts Up Into Pre-Biased Output Adjustable Output Voltage Soft-Start Output Current Foldback Limiting (Disabled During Soft-Start) Output Overvoltage Protection 5V LDO for External Gate Drive OPTI-LOOP® Compensation Minimizes COUT Low Shutdown IQ: 15μA Tiny 12-Pin 2mm × 3mm Thermally Enhanced DFN and MSOP Packages APPLICATIONS n n n n Automotive Systems Telecom Systems Industrial Equipment Distributed DC Power Systems TYPICAL APPLICATION High Efficiency Synchronous Step-Down Converter VIN TG 0.1μF LTC3854 RUN/SS ITH 2200pF 15k 100pF INTVCC 8.06k FB 42.2k SENSE– SENSE+ GND BG 4.7μF 10.2k 0.1μF BOOST SW 6.0μH AT 5.8mΩ DCR VOUT 5V 5A 330μF s2 0.1μF EFFICIENCY (%) 150μF 50V VIN 6V TO 38V 97.0 96.5 96.0 95.5 0.8 95.0 0.6 94.5 94.0 93.5 93.0 0.5 1.0 1.4 1.9 2.3 2.8 3.2 3.7 4.1 4.6 LOAD CURRENT (A) 5 0.4 0.2 0 Efficiency and Power Loss vs Load Current VIN = 6V 1.4 1.2 1.0 POWER LOSS (W) 3854 TA01b 3854 TA01 3854f 1 www.DataSheet4U.com LTC3854 (Note 1) ABSOLUTE MAXIMUM RATINGS Input Supply Voltage (VIN) ........................ 40V to –0.3V Top Side Driver Voltage (BOOST) ............... 46V to –0.3V Switch Voltage (SW) .................................. 40V to –5.0V INTVCC, BOOST-SW..................................... 6V to –0.3V SENSE+, SENSE– ......................................... 6V to –0.3V RUN/SS........................................................ 6V to –0.3V ITH, FB Voltages ....................................... 2.7V to –0.3V INTVCC Peak Output Current (Note 8) ....................40mA Operating Temperature Range (Notes 2, 3)..........................................–40°C to 85°C Maximum Junction Temperature ...................... 125°C Storage Temperature Range................... –65°C to 125°C PIN CONFIGURATION TOP VIEW TOP VIEW FB 1 ITH 2 RUN/SS 3 BOOST 4 TG 5 SW 6 13 12 SENSE+ 11 SENSE– 10 VIN 9 INTVCC 8 BG 7 GND MSE PACKAGE 12-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 40°C/W, θJC = 16°C/W EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB FB ITH RUN/SS BOOST TG SW 1 2 3 4 5 6 12 11 10 9 8 7 SENSE+ SENSE– VIN INTVCC BG GND 13 DDB PACKAGE 12-LEAD (3mm s 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 76°C/W, θJC = 10°C/W EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH LTC3854EDDB#PBF LTC3854IDDB#PBF LTC3854EMSE#PBF LTC3854IMSE#PBF TAPE AND REEL LTC3854EDDB#TRPBF LTC3854IDDB#TRPBF LTC3854EMSE#TRPBF LTC3854IMSE#TRPBF PART MARKING* LDPC LDPC 3854 3854 PACKAGE DESCRIPTION 12-Lead (3mm × 2mm) Plastic DFN 12-Lead (3mm × 2mm) Plastic DFN 12-Lead Plastic MSOP 12-Lead Plastic MSOP TEMPERATURE RANGE –40°C to 85°C –40°C to 85°C –40°C to 85°C –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 3854f 2 www.DataSheet4U.com LTC3854 ELECTRICAL CHARACTERISTICS SYMBOL VIN VFB IFB VREFLNREG VLOADREG PARAMETER Operating Input Voltage Range Regulated Feedback Voltage Feedback Current Reference Voltage Line Regulation Output Voltage Load Regulation Main Control Loop The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 15V,.


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