Features and Benefits

  • Wide Input Operating Range: 2.7V to 36V
  • Dual 1A Switches with Programmable Current Limit
  • Programmable Switching Frequency: 50kHz to 1MHz
  • Frequency Synchronization Up to 1MHz
  • ΔVIN Compensation Using Duty Cycle Control
  • Low Noise Topology
  • Programmable Input Over and Undervoltage Lockout
  • Cross Conduction Prevention Circuitry
  • Programmable Soft-Start
  • Low Shutdown Current: <1μA
  • 10-Lead MSOP and DFN Packages

Product Details

The LT3999 is a monolithic, high voltage, high frequency DC/DC transformer driver providing isolated power in a small solution footprint.

The LT3999 has two 1A current limited power switches that switch out of phase. The duty cycle is programmable to adjust the output voltage. The switching frequency is programmed up to 1MHz and can be synchronized to an external clock for more accurate placement of switcher harmonics. The input operating range is programmed with the precision undervoltage and overvoltage lockouts. The supply current is reduced to less than 1μA during shutdown. A user-defined RC time constant provides an adjustable soft-start capability by limiting the inrush current at start-up.

The LT3999 is available in a 10-lead MSOP and 3mm × 3mm DFN package with exposed pad.


  • Low Noise Isolated Supplies
  • Medical Instrument and Safety
  • Distributed Power
  • Multiple Output Supplies
  • Positive-to-Negative Supplies
  • Noise Immunity in Data Acquisition, RS232 and RS485

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 (2)

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:


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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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.