Features and Benefits

  • Dynamically Adjustable Output from 0.3V to 3.5V
  • Very Low Quiescent Current: Only 20µA During Operation
  • 600mA Output Current
  • Internal P-Channel MOSFET Bypass Transistor
  • High Efficiency: Up to 96%
  • 1.5MHz Constant Frequency Operation
  • No Schottky Diode Required
  • Low Dropout Operation: 100% Duty Cycle
  • 2.5V to 5V Input Voltage Range
  • Drives Optional External P-Channel MOSFET
  • Shutdown Mode Draws < 1µA Supply Current
  • Current Mode Operation for Excellent Line and Load Transient Response
  • Overtemperature Protected
  • Available in 8-Lead 3mm x 3mm DFN Package

Product Details

The LTC3403 is a high efficiency monolithic synchronous buck regulator optimized for WCDMA power amplifier applications. The output voltage can be dynamically programmed from 0.3V to 3.5V. At VOUT > 3.6V an internal bypass P-channel MOSFET connects VOUT directly to VIN, eliminating power loss through the inductor. Selectable forced continuous mode enables fast VOUT response to the controlling input.

Supply current is only 20µA in Burst Mode® operation and drops to <1µA in shutdown. The 2.5V to 5V input voltage range makes the LTC3403 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems.

Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode.

The LTC3403 is available in a low profile 8-lead 3mm x 3mm DFN package.


  • WCDMA Cell Phone Power Amplifiers
  • Wireless Modems

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.

Evaluation Kits (1)

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:



LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.


Design tools for the following parts are available in LTpowerCAD:


Product Recommendations

LTC3403 Companion Parts

Recommended Related Parts

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.

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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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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Evaluation Boards Pricing displayed is based on 1-piece.
Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.
Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.