LTC3854 - Small Footprint, Wide VIN Range Synchronous Step-Down DC/DC Controller

Features

  • 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 Thermally Enhanced 12-Pin 2mm × 3mm DFN and MSOP Packages

Typical Application

LTC3854 Typical Application
LTC3854 Typical Application

Description

The LTC3854 is a high performance synchronous stepdown switching DC/DC 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.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC3854EDDB#PBF 3x2 DFN-12 DDB E 05-08-1723 Yes
LTC3854EDDB#TRMPBF 3x2 DFN-12 DDB E 05-08-1723 Yes
LTC3854EDDB#TRPBF 3x2 DFN-12 DDB E 05-08-1723 Yes
LTC3854EMSE#PBF MS-12E MSE E 05-08-1666 Yes
LTC3854EMSE#TRPBF MS-12E MSE E 05-08-1666 Yes
LTC3854IDDB#PBF 3x2 DFN-12 DDB I 05-08-1723 Yes
LTC3854IDDB#TRMPBF 3x2 DFN-12 DDB I 05-08-1723 Yes
LTC3854IDDB#TRPBF 3x2 DFN-12 DDB I 05-08-1723 Yes
LTC3854IMSE#PBF MS-12E MSE I 05-08-1666 Yes
LTC3854IMSE#TRPBF MS-12E MSE I 05-08-1666 Yes


LTC3854 Package Drawing
LTC3854 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC3854EDDB#PBF 3x2 DFN-12 E $2.39 Yes
LTC3854EDDB#TRMPBF 3x2 DFN-12 E $2.36 $1.70 Yes
LTC3854EDDB#TRPBF 3x2 DFN-12 E $2.36 $1.65 Yes
LTC3854EMSE#PBF MS-12E E $2.36 $1.65 Yes
LTC3854EMSE#TRPBF MS-12E E $1.71 Yes
LTC3854IDDB#PBF 3x2 DFN-12 I $2.69 Yes
LTC3854IDDB#TRMPBF 3x2 DFN-12 I $2.69 $1.93 Yes
LTC3854IDDB#TRPBF 3x2 DFN-12 I $2.69 $1.88 Yes
LTC3854IMSE#PBF MS-12E I $2.69 $1.88 Yes
LTC3854IMSE#TRPBF MS-12E I $1.94 Yes
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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.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1271A LTC3854EDDB Demo Board | 4.5V ≤ VIN ≤ 14V, VOUT = 1.5V @ 15A $100.00
DC1450A LTC3854EDDB Demo Board | 4.5V ≤ VIN ≤ 26V, VOUT = 2.5V @ 5A $100.00
DC1487A LTC3854EMSE Demo Board | 4.5V ≤ VIN ≤ 34V, VOUT = 2.5V @ 12A $100.00
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Click here to view our complete list of demo boards

Applications

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

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LTC3854

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

To open the project file for this circuit:

Design tools for the following parts are available in LTpowerCAD:
LTC3854

Technical Support