LTC3809-1 - No Rsense, Low Input Voltage, Synchronous DC/DC Controller with Output Tracking


  • Programmable Output Voltage Tracking
  • No Current Sense Resistor Required
  • Constant Frequency Current Mode Operation for Excellent Line and Load Transient Response
  • Wide VIN Range: 2.75V to 9.8V
  • Wide VOUT Range: 0.6V to VIN
  • 0.6V ±1.5% Reference
  • Low Dropout Operation: 100% Duty Cycle
  • Selectable Burst Mode/Pulse Skipping/Forced Continuous Operation
  • Auxiliary Winding Regulation
  • Internal Soft-Start Circuitry
  • Selectable Maximum Peak Current Sense Threshold
  • Output Overvoltage Protection
  • Micropower Shutdown: IQ = 9µA
  • Tiny Thermally Enhanced Leadless (3mm × 3mm) DFN or 10-lead MSOP Packages

Typical Application

LTC3809-1 Typical Application
LTC3809-1 Typical Application


The LTC3809-1 is a synchronous step-down switching regulator controller that drives external complementary power MOSFETs using few external components. The constant frequency current mode architecture with MOSFET VDS sensing eliminates the need for a current sense resistor and improves efficiency.

Optional Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation, extending operating time in battery powered systems. Burst Mode is inhibited when the MODE pin is pulled low to reduce noise and RF interference.

The LTC3809-1 allows either coincident or ratiometric output voltage tracking. Switching frequency is fixed at 550kHz. Fault protection is provided by an overvoltage comparator and a short-circuit current limit comparator.

The LTC3809-1 is available in the tiny footprint thermally enhanced DFN and 10-lead MSOP packages.

LTC3809 PLL, Selectable Spread Spectrum, Power Good 3x3 DFN-10, MS-10E
LTC3809-1 Tracking 3x3 DFN-10, MS-10E
LTC3808 PLL, Selectable Spread Spectrum, Tracking, Power Good 4x3 DFN-14, SSOP-16


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
LTC3809EDD-1#PBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3809EDD-1#TRPBF 3x3 DFN-10 DD E 05-08-1699 Yes
LTC3809EMSE-1#PBF MS-10E MSE E 05-08-1664 Yes
LTC3809EMSE-1#TRPBF MS-10E MSE E 05-08-1664 Yes
LTC3809IDD-1#PBF 3x3 DFN-10 DD I 05-08-1699 Yes
LTC3809IDD-1#TRPBF 3x3 DFN-10 DD I 05-08-1699 Yes
LTC3809IMSE-1#PBF MS-10E MSE I 05-08-1664 Yes
LTC3809IMSE-1#TRPBF MS-10E MSE I 05-08-1664 Yes

LTC3809-1 Package Drawing
LTC3809-1 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
LTC3809EDD-1#PBF 3x3 DFN-10 E $3.57 $2.50 Yes
LTC3809EDD-1#TRPBF 3x3 DFN-10 E $2.60 Yes
LTC3809EMSE-1#PBF MS-10E E $3.57 $2.50 Yes
LTC3809EMSE-1#TRPBF MS-10E E $2.56 Yes
LTC3809IDD-1#PBF 3x3 DFN-10 I $3.70 $2.59 Yes
LTC3809IDD-1#TRPBF 3x3 DFN-10 I $3.05 Yes
LTC3809IMSE-1#PBF MS-10E I $3.70 $2.59 Yes
LTC3809IMSE-1#TRPBF MS-10E I $3.05 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
DC882A LTC3809EDD-1 | Synch Step-Down Converter $125.00
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  • 1- or 2-Cell Lithium-Ion Powered Devices
  • Notebook and Palmtop Computers, PDAs
  • Portable Instruments
  • Distributed DC Power Systems

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