LTC3879 - Fast, Wide Operating Range No RSENSE Step-Down Controller


  • Wide VIN Range: 4V to 38V
  • ±1% 0.6V Voltage Reference
  • Extremely Fast Transient Response
  • tON(MIN): 43ns
  • No RSENSE™ Valley Current Mode Control
  • Stable with Low ESR Ceramic COUT
  • Supports Smooth Start-Up in Pre-Biased Output
  • Optimized for High Step-Down Ratios
  • Adjustable Output Voltage Soft-Start or Tracking
  • Power Good Output Voltage Monitor
  • Dual N-Channel MOSFET Synchronous Drive
  • Adjustable Switching Frequency
  • Programmable Current Limit with Foldback
  • Output Overvoltage Protection
  • 16-Pin MSOP and 3mm × 3mm QFN Packages

Typical Application

LTC3879 Typical Application
LTC3879 Typical Application


The LTC3879 is a synchronous step-down switching regulator controller optimized for high switching frequency and fast transient response. The constant on-time valley current mode architecture allows for a wide input range, including very low duty factor operation. No external sense resistor or slope compensation is required. System flexibility is offered through a user-programmable soft-start pin and independent RUN pin. The voltage ramping soft-start function can be programmed with a capacitor or made to track an external reference source.

Operating frequency is set by an external resistor and compensated for variations in VIN to offer excellent line stability. Discontinuous mode operation provides high efficiency during light load conditions. A forced continuous control pin allows the user to reduce noise and RF interference. Safety features include output overvoltage protection and programmable current limit with foldback. The current limit is user programmable.

The LTC3879 allows operation from 4V to 38V at the input and from 0.6V to 90% VIN at the output. The LTC3879 is
available in a small 16-pin thermally enhanced MSOP or 3mm × 3mm QFN 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
LTC3879EMSE#PBF MS-16E MSE E 05-08-1667 Yes
LTC3879EMSE#TRPBF MS-16E MSE E 05-08-1667 Yes
LTC3879EUD#PBF 3x3 QFN-16 UD E 05-08-1700 Yes
LTC3879EUD#TRPBF 3x3 QFN-16 UD E 05-08-1700 Yes
LTC3879IMSE#PBF MS-16E MSE I 05-08-1667 Yes
LTC3879IMSE#TRPBF MS-16E MSE I 05-08-1667 Yes
LTC3879IUD#PBF 3x3 QFN-16 UD I 05-08-1700 Yes
LTC3879IUD#TRPBF 3x3 QFN-16 UD I 05-08-1700 Yes

LTC3879 Package Drawing
LTC3879 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
LTC3879EMSE#PBF MS-16E E $2.49 $1.76 Yes
LTC3879EMSE#TRPBF MS-16E E $1.82 Yes
LTC3879EUD#PBF 3x3 QFN-16 E $2.49 $1.76 Yes
LTC3879EUD#TRPBF 3x3 QFN-16 E $1.82 Yes
LTC3879IMSE#PBF MS-16E I $2.84 $1.99 Yes
LTC3879IMSE#TRPBF MS-16E I $2.05 Yes
LTC3879IUD#PBF 3x3 QFN-16 I $2.84 $1.99 Yes
LTC3879IUD#TRPBF 3x3 QFN-16 I $2.05 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
DC1289A LTC3879EUD Demo Board | No RSENSE, 4.5V ≤ VIN ≤ 14V, Vout = 1.2V @ 15A $125.00
DC1345A LTC3879EMSE Demo Board | 4.5V ≤ VIN ≤ 34, VOUT = 1.2V @ 12A $125.00
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Click here to view our complete list of demo boards


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