Overview

Features and Benefits

  • 3.3A, 42V Combined Power Switch
  • Master/Slave (1.9A/1.4A) Switch Design
  • Output Short Circuit Protection
  • Wide Input Range: 2.5V to 22V Operating, 40V Maximum Transient
  • Switching Frequency Up to 2.5MHz
  • Easily Configurable as a Boost, SEPIC, Inverting or Flyback Converter
  • User Configurable Undervoltage Lockout
  • Low VCESAT Switch: 250mV at 2.75A (Typical)
  • Can be Synchronized to External Clock
  • Can Be Synchronized to other Switching Regulators
  • High Gain SHDN Pin Accepts Slowly Varying Input Signals
  • 14-Pin 4mm × 3mm DFN and 16-Lead MSE Packages

Product Details

The LT3581 is a PWM DC/DC converter with built-in fault protection features to aid in protecting against output shorts, input/output overvoltages, and overtemperature conditions. The part consists of a 42V master switch, and a 42V slave switch that can be tied together for a total current limit of 3.3A.

The LT3581 is ideal for many local power supply designs. It can be easily configured in Boost, SEPIC, Inverting or Flyback configurations, and is capable of generating 12V at 830mA, or –12V at 625mA from a 5V input. In addition, the LT3581’s slave switch allows the part to be configured in high voltage, high power charge pump topologies that are very efficient and require fewer components than traditional circuits.

The LT3581’s switching frequency range can be set between 200kHz and 2.5MHz. The part may be clocked internally at a frequency set by the resistor from the RT pin to ground, or it may be synchronized to an external clock. A buffered version of the clock signal is driven out of the CLKOUT pin, and may be used to synchronize other compatible switching regulator ICs to the LT3581.

The LT3581 also features innovative SHDN pin circuitry that allows for slowly varying input signals and an adjustable undervoltage lockout function. Additional features such as frequency foldback and soft-start are integrated. The LT3581 is available in 14-Pin 4mm × 3mm DFN and 16-Lead MSE packages.

Applications

  • Local Power Supply
  • Vacuum Fluorescent Display (VFD) Bias Supplies
  • TFT-LCD Bias Supplies
  • Automotive Engine Control Unit (ECU) Power

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

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.

LTspice

Models for the following parts are available in LTspice:

LT3581

LTpowerCAD

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.

LTPowerCAD

Design tools for the following parts are available in LTpowerCAD:

LT3581

Product Recommendations

LT3581 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.
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.