LTC3871 - Bidirectional PolyPhase® Synchronous Buck or Boost Controller


  • Unique Architecture Allows Dynamic Regulation of Input Voltage, Output Voltage or Current
  • VHIGH Voltages Up to 100V
  • VLOW Voltages Up to 30V
  • Synchronous Rectification: Up to 97% Efficiency
  • LTC-Proprietary Advanced Current Mode Control
  • ±1% Voltage Regulation Accuracy Over Temperature
  • Accurate, Programmable Output Current Monitoring and Regulation for Both Buck and Boost Operation
  • Selectable Buck and Boost Current Sense Limits
  • Engineered for Diagnostic Coverage in ISO26262 Systems
  • Programmable DRVCC/EXTVCC Optimizes Efficiency
  • Programmable VHIGH UV and OV Thresholds
  • Programmable VLOW OV Threshold
  • Phase-Lockable Frequency: 60kHz to 460kHz
  • Multiphase/Multi-ICs Operation Up to 12 Phases
  • Selectable CCM/DCM Modes
  • Thermally Enhanced 48-Lead LQFP Package

Typical Application

LTC3871 Typical Application
LTC3871 Typical Application


The LTC®3871 is a high performance bidirectional buck or boost switching regulator controller that operates in either buck or boost mode on demand. It regulates in buck mode from VHIGH-to-VLOW and boost mode from VLOW-to-VHIGH depending on a control signal, making it ideal for 48V/12V automotive dual battery systems. An accurate current programming loop regulates the maximum current that can be delivered in either direction. The LTC3871 allows both batteries to supply energy to the load simultaneously by converting energy from one battery to the other.

Its proprietary constant-frequency current mode architecture enhances the signal-to-noise ratio enabling low noise operation and provides excellent current matching between phases. Additional features include discontinuous or continuous mode of operation, OV/UV monitors, independent loop compensation for buck and boost operation, accurate output current monitoring and overcurrent protection.


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
LTC3871ELXE#PBF 7mm x 7mm LQFP-48 LXE E 05-08-1832 Yes
LTC3871HLXE#PBF 7mm x 7mm LQFP-48 LXE H 05-08-1832 Yes
LTC3871ILXE#PBF 7mm x 7mm LQFP-48 LXE I 05-08-1832 Yes

LTC3871 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
LTC3871ELXE#PBF 7mm x 7mm LQFP-48 E $7.71 $5.40 Yes
LTC3871HLXE#PBF 7mm x 7mm LQFP-48 H $9.74 $6.82 Yes
LTC3871ILXE#PBF 7mm x 7mm LQFP-48 I $9.22 $6.45 Yes
Buy NowRequest Samples
* 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
DC2348A-A LTC3871HLXE#PBF Demo Board | Bidirectional Controller, Buck Mode: 30V ≤ VIN ≤ 75V, VOUT = 12V @ 60A; Boost Mode: 10V ≤ VIN ≤ 13V, VOUT = 48V @ 15A $400.00
DC2348A-B LTC3871HLXE#PBF Demo Board | Bidirectional Controller, Buck Mode: 30V ≤ VIN ≤ 75V, VOUT = 12V @ 30A; Boost Mode: 10V ≤ VIN ≤ 13V, VOUT = 48V @ 7.5A $300.00
Buy Now
Click here to view our complete list of demo boards


  • Automotive 48V/12V Dual Battery Systems
  • Backup Power Systems

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email with questions and comments.

Design Tools


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

Models for the following parts are available in LTspice:


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:
LTC3871 Parallel
LTC3871(Boost) Parallel
LTC3871(Buck) Parallel

Technical Support