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LTC3851 - Synchronous Step-Down Switching Regulator Controller

Features

  • Click Here for LTC3851 Evaluation Kit
  • Wide VIN Range: 4V to 38V Operation
  • RSENSE 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 COUT
  • Selectable Continuous, Pulse-Skipping or Burst Mode Operation at Light Loads
  • Low Shutdown IQ: 20μA
  • VOUT Range: 0.8V to 5.5V
  • Thermally Enhanced 16-Lead MSOP, 16-Lead Narrow SSOP or 3mm × 3mm QFN Package

Typical Application

LTC3851
LTC3851
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Description

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.
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Packaging

QFN-16, SSOP-16, MS-16

LTC3851
LTC3851
LTC3851
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Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC3851EGN#PBF SSOP 16 E $2.44 $1.71 View
LTC3851EGN#TRPBF SSOP 16 E   $1.77 View
LTC3851EMSE#PBF MSOP 16 E $2.44 $1.71 View
LTC3851EMSE#TRPBF MSOP 16 E   $1.77 View
LTC3851EMSE-1#PBF MSOP 16 E $2.44 $1.71 View
LTC3851EMSE-1#TRPBF MSOP 16 E   $1.77 View
LTC3851EUD#PBF QFN 16 E $2.44 $1.71 View
LTC3851EUD#TRPBF QFN 16 E   $1.77 View
LTC3851EUD-1#PBF QFN 16 E $2.44 $1.71 View
LTC3851EUD-1#TRPBF QFN 16 E   $1.77 View
LTC3851IGN#PBF SSOP 16 I $2.77 $1.94 View
LTC3851IGN#TRPBF SSOP 16 I   $2.00 View
LTC3851IMSE#PBF MSOP 16 I $2.77 $1.94 View
LTC3851IMSE#TRPBF MSOP 16 I   $2.00 View
LTC3851IMSE-1#PBF MSOP 16 I $2.77 $1.94 View
LTC3851IMSE-1#TRPBF MSOP 16 I   $2.00 View
LTC3851IUD#PBF QFN 16 I $2.77 $1.94 View
LTC3851IUD#TRPBF QFN 16 I   $2.00 View
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Evaluation Kits

Part Number Description Price
DC1171A-A LTC3851EGN (Rsense) Demo Board | 4.5V < Vin < 14V, Vout: 1.5V/15A $100.00
DC1171A-B LTC3851EGN (DCR) Demo Board | 4.5V < Vin < 14V, Vout: 1.5V/15A $100.00
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Applications

  • Automotive Systems
  • Telecom Systems
  • Industrial Equipment
  • Distributed DC Power Systems
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Simulate

To simulate selected Linear Technology products, please download LTSpice / SwitcherCAD III. This powerful schematic capture and simulation tool includes macro models for 80% of Linear Technology's switching regulators, over 200 op amp models, as well as resistors, transistors and MOSFET models.

For other simulation tools, visit our Design Simulation and Device Models page.

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