Features and Benefits

  • Wide Input Range:
    • Operation from 3.6V to 36V
    • Overvoltage Lockout Protects Circuit Through 55V Transients on Input
  • 500mA Output Current Switching Regulator
  • High Switching Frequency: 750kHz
  • 200mA Low Dropout Linear Regulator
    • 1.2V to 16V Input; 0.8V to 8V Output
    • 310mV Dropout Voltage VCC2 to OUT2
  • Precision Programmable Undervoltage Lockout
  • Short-Circuit Robust
  • Internal Soft-Start
  • <2μA Shutdown Current
  • Small Thermally Enhanced 16-Lead (3mm × 3mm) QFN and 12-Lead MSE Packages

Product Details

The LT3645 is a dual output regulator combining a 500mA buck regulator and a 200mA low dropout linear regulator (LDO). The wide input voltage range of 3.6V to 36V makes the LT3645 suitable for regulating power from a wide variety of sources, including 24V industrial supplies and automotive batteries. Its high operating frequency allows the use of tiny, low cost inductors and capacitors, resulting in a very small solution.

Cycle-by-cycle current limit and frequency foldback provide protection against shorted outputs. Soft-start and frequency foldback eliminate input current surge during start-up.

The linear regulator operates from the VCC2 pin at voltages down to 1.2V. It supplies 200mA of output current with a typical dropout voltage of 310mV.

Other features of the LT3645 include a <2μA shutdown, short circuit protection, soft-start and thermal shutdown. The LT3645 is available in the thermally enhanced 16-lead (3mm × 3mm) QFN package, or a 12-lead MSE package.


  • Automotive CMOS Image Sensors
  • Industrial/Automotive Micro-Controller Supply

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.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.


Models for the following parts are available in LTspice:


Product Recommendations

LT3645 Companion Parts

Recommended Related Parts

Design Resources

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PCN-PDN Information

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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.