LTC3856 - 2-Phase Synchronous Step-Down DC/DC Controller with Diffamp


  • PolyPhase® Controller Reduces Input and Output Capacitance and Power Supply Induced Noise
  • Wide VIN Range: 4.5V to 38V Operation
  • ±0.75%, 0.6V Reference Voltage Accuracy
  • High Efficiency: Up to 95%
  • Programmable Burst Mode® Operation or Stage Shedding™ for Highest Light Load Efficiency
  • Active Voltage Positioning (AVP)
  • RSENSE or DCR Current Sensing
  • Programmable DCR Temperature Compensation
  • Phase-Lockable Fixed Frequency: 250kHz to 770kHz
  • True Remote Sense Differential Amplifier
  • Dual N-Channel MOSFET Synchronous Drive
  • VOUT Range: 0.6V to 5V without Differential Amplifier
  • VOUT Range: 0.6V to 3.3V with Differential Amplifier
  • Adjustable Soft-Start or VOUT Tracking
  • Stackable for Up to 12-Phase Operation
  • 32-Pin (5mm × 5mm) QFN and 38-Pin TSSOP Packages

Typical Application

LTC3856 Typical Application
LTC3856 Typical Application


The LTC3856 is a single output, dual channel PolyPhase synchronous step-down DC/DC controller that drives all N-channel power MOSFET stages. This device includes a high speed differential amplifier for remote output voltage sense. Power loss and supply noise are minimized by operating the two controller output stages out-of-phase and up to 12-phase operation can be achieved.

The LTC3856 monitors the output current by sensing the voltage drop across the output inductor (DCR) or by using a sense resistor. DCR temperature compensation maintains an accurate current sense threshold over a broad temperature range. A constant-frequency, current mode architecture allows a phase-lockable frequency of up to 770kHz.

A wide 4.5V to 38V input supply range encompasses most intermediate bus voltages and battery chemistries. Burst Mode operation, continuous or Stage Shedding modes are supported. A TK/SS pin shared by both channels ramps the output voltage during start-up.


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
LTC3856EFE#PBF TSSOP-38 FE E 05-08-1772 Yes
LTC3856EFE#TRPBF TSSOP-38 FE E 05-08-1772 Yes
LTC3856EUH#PBF 5x5 QFN-32 UH E 05-08-1693 Yes
LTC3856EUH#TRPBF 5x5 QFN-32 UH E 05-08-1693 Yes
LTC3856IFE#PBF TSSOP-38 FE I 05-08-1772 Yes
LTC3856IFE#TRPBF TSSOP-38 FE I 05-08-1772 Yes
LTC3856IUH#PBF 5x5 QFN-32 UH I 05-08-1693 Yes
LTC3856IUH#TRPBF 5x5 QFN-32 UH I 05-08-1693 Yes

LTC3856 Package Drawing
LTC3856 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
LTC3856EFE#PBF TSSOP-38 E $4.96 $3.47 Yes
LTC3856EFE#TRPBF TSSOP-38 E $3.53 Yes
LTC3856EUH#PBF 5x5 QFN-32 E $4.54 $3.18 Yes
LTC3856EUH#TRPBF 5x5 QFN-32 E $3.24 Yes
LTC3856IFE#PBF TSSOP-38 I $5.46 $3.82 Yes
LTC3856IFE#TRPBF TSSOP-38 I $3.88 Yes
LTC3856IUH#PBF 5x5 QFN-32 I $5.22 $3.65 Yes
LTC3856IUH#TRPBF 5x5 QFN-32 I $3.71 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
DC1580A LTC3856EUH Demo Board | 4.5V ≤ VIN ≤ 14V, VOUT = 1.5V @ 50A $150.00
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Click here to view our complete list of demo boards


  • Telecom and Datacom Systems
  • Industrial and Medical Instruments
  • DC Power Distribution Systems
  • Computer Systems

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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

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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:
LTC3856 Parallel

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