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
AEC-Q100 data available for specific packages
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 |
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 | ||
| Buy Now • Request Samples | ||||||
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 | |
| Buy Now | |||
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| 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 | ||
| Buy Now • Request Samples | ||||||
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:
- Step 1: If you have not installed LTpowerCAD on this computer, download and install LTpowerCAD
- Step 2: Once LTpowerCAD is installed, click on the link(s) below to open the project file
- LTC3854 Project - Synchronous Step-Down Switching Supply with Rsense Current Sensing (4.5-14V to 1.5V @ 15A)
- LTC3854 Project - Synchronous Step-Down Switching Supply with Rsense Current Sensing (4.5-34V to 2.5V @ 12A)
- LTC3854 Project - Synchronous Step-Down Switching Supply with Inductor DCR Current Sensing (4.5-14V to 1.5V @ 15A)
- LTC3854 Project - Synchronous Step-Down Switching Supply with Inductor DCR Current Sensing (4.5-25V to 2.5V @ 5A)
- LTC3854 Project - Synchronous Step-Down Switching Supply with Inductor DCR Current Sensing (4.5-34V to 2.5V @ 12A)
- Step 3: If LTpowerCAD does not automatically open after clicking the link above, you can open the project file by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTpowerCAD and open the project file by selecting 'Open Project' from the 'File' menu
Design tools for the following parts are available in LTpowerCAD:
LTC3854
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
