LTC3855 - Dual, Multiphase Synchronous DC/DC Controller with Differential Remote Sense


  • Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
  • High Efficiency: Up to 95%
  • RSENSE or DCR Current Sensing
  • Programmable DCR Temperature Compensation
  • ±0.75% 0.6V Output Voltage Accuracy
  • Phase-Lockable Fixed Frequency 250kHz to 770kHz
  • True Remote Sensing Differential Amplifier
  • Dual N-Channel MOSFET Synchronous Drive
  • Wide VIN Range: 4.5V to 38V
  • VOUT Range: 0.6V to 12.5V without Differential Amplifier
  • VOUT Range: 0.6V to 3.3V with Differential Amplifier
  • Clock Input and Output for Up to 12-Phase Operation
  • Adjustable Soft-Start or VOUT Tracking
  • Foldback Output Current Limiting
  • Output Overvoltage Protection
  • 40-Pin (6mm × 6mm) QFN and 38-Lead FE Packages

Typical Application

LTC3855 Typical Application
LTC3855 Typical Application


The LTC3855 is a dual PolyPhase current mode synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages. It includes a high speed differential remote sense amplifier. The maximum current sense voltage is programmable for either 30mV, 50mV or 75mV, allowing the use of either the inductor DCR or a discrete sense resistor as the sensing element.

The LTC3855 features a precision 0.6V reference and can produce output voltages up to 12.5V. A wide 4.5V to 38V input supply range encompasses most intermediate bus voltages and battery chemistries. Power loss and supply noise are minimized by operating the two controller output stages out of phase. Burst Mode operation, continuous or pulse-skipping modes are supported.

The LTC3855 can be configured for up to 12-phase operation, has DCR temperature compensation, two power good signals and two current limit set pins. The LTC3855 is available in low profile 40-pin 6mm × 6mm QFN and 38-lead exposed pad FE packages.


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
LTC3855EFE#PBF TSSOP-38 FE E 05-08-1772 Yes
LTC3855EFE#TRPBF TSSOP-38 FE E 05-08-1772 Yes
LTC3855EUJ#PBF 6x6 QFN-40 UJ E 05-08-1728 Yes
LTC3855EUJ#TRPBF 6x6 QFN-40 UJ E 05-08-1728 Yes
LTC3855IFE#PBF TSSOP-38 FE I 05-08-1772 Yes
LTC3855IFE#TRPBF TSSOP-38 FE I 05-08-1772 Yes
LTC3855IUJ#PBF 6x6 QFN-40 UJ I 05-08-1728 Yes
LTC3855IUJ#TRPBF 6x6 QFN-40 UJ I 05-08-1728 Yes

LTC3855 Package Drawing
LTC3855 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
LTC3855EFE#PBF TSSOP-38 E $4.86 $3.40 Yes
LTC3855EFE#TRPBF TSSOP-38 E $3.46 Yes
LTC3855EUJ#PBF 6x6 QFN-40 E $4.54 $3.18 Yes
LTC3855EUJ#TRPBF 6x6 QFN-40 E $3.24 Yes
LTC3855IFE#PBF TSSOP-38 I $5.54 $3.88 Yes
LTC3855IFE#TRPBF TSSOP-38 I $3.94 Yes
LTC3855IUJ#PBF 6x6 QFN-40 I $5.13 $3.59 Yes
LTC3855IUJ#TRPBF 6x6 QFN-40 I $3.65 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
DC1441A LTC3855EUJ Demo Board | Dual Output, VIN = 4.5V to 14V, VOUT1 = 1.8V @ 17A, VOUT2 = 1.2V @ 17A $200.00
DC1586A LTC3855EUJ Demo Board | Dual Output, VIN = 4.5V to 25V, VOUT1 = 3.3V @ 5A, VOUT2 = 2.5V @ 5A $200.00
DC1617A-A LTC3855EFE Demo Board | Dual Output VIN = 4.5V to 26V, VOUT1 = 2.5V @ 15A, VOUT2 = 1.8V @ 15A $200.00
DC1617A-B LTC3855EFE Demo Board | Dual Output VIN = 13V to 36V, VOUT1 = 12V @ 6A, VOUT2 = 5V @ 10A $200.00
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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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LTC3855 Parallel

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