Features and Benefits

  • No Current Sense Resistor Required
  • Selectable Spread Spectrum Frequency Modulation for Low Noise Operation
  • Constant Frequency Current Mode Operation for Excellent Line and Load Transient Response
  • True PLL for Frequency Locking or Adjustment (Frequency Range: 250kHz to 750kHz)
  • 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
  • Output Overvoltage Protection
  • Micropower Shutdown: IQ = 9µA
  • Tiny Thermally Enhanced Leadless (3mm × 3mm) DFN and 10-lead MSOP Packages

Product Details

The LTC3809 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.

For noise sensitive applications, the LTC3809 can be externally synchronized from 250kHz to 750kHz. Burst Mode is inhibited during synchronization or when the SYNC/MODE pin is pulled low to reduce noise and RF interference. To further reduce EMI, the LTC3809 incorporates a novel spread spectrum frequency modulation technique.

Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation, extending operating time in battery-powered systems.

The switching frequency can be programmed up to 750kHz, allowing the use of small surface mount inductors and capacitors.

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

Features Package
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


  • 1- or 2-Cell Lithium-Ion Powered Devices
  • Portable Instruments
  • Distributed DC Power Systems

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Tools & Simulations


LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.


Models for the following parts are available in LTspice:


Product Recommendations

LTC3809 Companion Parts

Recommended Related Parts

Recommended Suggested Oscillator

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

PCN-PDN Information

Sample & Buy

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