LTC3851

PRODUCTION

Synchronous Step-Down Switching Regulator Controller

Part Models: 12
1ku List Price: Starting From $2.09

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Part Details

Wide V_IN Range: 4V to 38V Operation
R_SENSE or DCR Current Sensing
±1% Output Voltage Accuracy
Phase-Lockable Fixed Frequency: 250kHz to 750kHz
Dual N-Channel MOSFET Synchronous Drive
Very Low Dropout Operation: 99% Duty Cycle
Adjustable Output Voltage Soft-Start or Tracking
Output Current Foldback Limiting
Output Overvoltage Protection
5V Internal Regulator
OPTI-LOOP^® Compensation Minimizes C_OUT
Selectable Continuous, Pulse-Skipping or Burst Mode^® Operation at Light Loads
Low Shutdown I_Q: 20μA
V_OUT Range: 0.8V to 5.5V
Thermally Enhanced 16-Lead MSOP, 16-Lead Narrow SSOP or 3mm × 3mm QFN Package

The LTC3851 is a high performance synchronous step-down switching regulator controller that drives an all N-channel synchronous power MOSFET stage. A constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz.

OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3851 features a precision 0.8V reference that is compatible with a wide 4V to 38V input supply range.

The TK/SS pin ramps the output voltage during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode operation, pulse skipping mode or continuous inductor current mode at light loads and allows the IC to be synchronized to an external clock.

The LTC3851-1 is a version with a power good output signal instead of adjustable current limit.


	Features
LTC3851	Not Recommended For New Designs
LTC3851-1	Not Recommended For New Designs
LTC3851A	Adjustable Current Limit
LTC3851A-1	PGOOD Output

Applications

Automotive Systems
Telecom Systems
Industrial Equipment
Distributed DC Power Systems

Part Models: 12
1ku List Price: Starting From $2.09

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC3851EGN#PBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851EGN#TRPBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851EMSE#PBF	16-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851EMSE#TRPBF	16-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851EUD#PBF	16-Lead QFN (3mm x 3mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851EUD#TRPBF	16-Lead QFN (3mm x 3mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851IGN#PBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851IGN#TRPBF	16-Lead SSOP (Narrow 0.15 Inch)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851IMSE#PBF	16-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851IMSE#TRPBF	16-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851IUD#PBF	16-Lead QFN (3mm x 3mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3851IUD#TRPBF	16-Lead QFN (3mm x 3mm x 0.75mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Oct 11, 2022 - 22_0235 Epoxy Change from Henkel 8290 to 8290A for GN Package
		PCN22_0235_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LTC3851EGN#PBF	PRODUCTION
LTC3851EGN#TRPBF	PRODUCTION
LTC3851IGN#PBF	PRODUCTION
LTC3851IGN#TRPBF	PRODUCTION
Apr 6, 2022 - 22_0066 Laser Top Mark for 16QSOP Assembled in ADPG [PNG]
		PCN22_0066_Form Material_Report Delta Qualification Matrix
LTC3851EGN#PBF	PRODUCTION
LTC3851EGN#TRPBF	PRODUCTION
LTC3851IGN#PBF	PRODUCTION
LTC3851IGN#TRPBF	PRODUCTION
Nov 8, 2021 - 20_0245 Notification of Wafer Fab Location Change for 0.6µm BICMOS Process Devices from ADI Milpitas (Hillview) to Vanguard Int. (Taiwan)
		PCN20_0245_Form Material_Report Delta Qualification Matrix Other Qualification Results Summary
LTC3851EGN#PBF	PRODUCTION
LTC3851EGN#TRPBF	PRODUCTION
LTC3851EMSE#PBF	PRODUCTION
LTC3851EMSE#TRPBF	PRODUCTION
LTC3851EUD#PBF	PRODUCTION
LTC3851EUD#TRPBF	PRODUCTION
LTC3851IGN#PBF	PRODUCTION
LTC3851IGN#TRPBF	PRODUCTION
LTC3851IMSE#PBF	PRODUCTION
LTC3851IMSE#TRPBF	PRODUCTION
LTC3851IUD#PBF	PRODUCTION
LTC3851IUD#TRPBF	PRODUCTION
Feb 4, 2020 - 20_0132 Laser Top Mark for 16-Lead MSOP Packages Assembled in ADPG and UTAC
		PCN20_0132_Form Material_Report
LTC3851EMSE#PBF	PRODUCTION
LTC3851EMSE#TRPBF	PRODUCTION
LTC3851IMSE#PBF	PRODUCTION
LTC3851IMSE#TRPBF	PRODUCTION
Oct 11, 2022 - 22_0244 Epoxy Change from Henkel 8290 to 8290A for MSOP Package
		PCN22_0244_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LTC3851IMSE#PBF	PRODUCTION
LTC3851IMSE#TRPBF	PRODUCTION
Apr 18, 2022 - 22_0050 UTAC Thai Limited (UTL) as Alternate Assembly Site for MSOP Packages / Devices
		PCN22_0050_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LTC3851IMSE#PBF	PRODUCTION
LTC3851IMSE#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Hardware Ecosystem

Parts	Product Life Cycle	Description
Circuit Monitors 1
LTC2960	RECOMMENDED FOR NEW DESIGNS	36V Nano-Current Two-Input Voltage Monitor
Oscillators 1
LTC6909	PRODUCTION	1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation
Power System Management (PSM) & Sequencers 1
LTC2974	RECOMMENDED FOR NEW DESIGNS	4-Channel PMBus Power System Manager Featuring Accurate Output Current Measurement

Parts	Product Life Cycle	Description
LTC3851A	RECOMMENDED FOR NEW DESIGNS	Synchronous Step-Down Switching Regulator Controller

Tools & Simulations

LTspice 1

LTC3851 - Step-Down (Buck) Regulators

Models for the following parts are available in LTspice:

LTC3851
LTC3851-1
LTC3851A
LTC3851A-1

LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:

LTC3851A
LTC3851A-1

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.