LT3581 - 3.3A Boost/Inverting DC/DC Converter with Fault Protection

Features

  • 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
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT3581 Typical Application
LT3581 Typical Application

Description

The LT®3581 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.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LT3581EDE#PBF 4x3 DFN-14 DE E 05-08-1708 Yes
LT3581EDE#TRPBF 4x3 DFN-14 DE E 05-08-1708 Yes
LT3581EMSE#PBF MS-16E MSE E 05-08-1667 Yes
LT3581EMSE#TRPBF MS-16E MSE E 05-08-1667 Yes
LT3581HDE#PBF 4x3 DFN-14 DE H 05-08-1708 Yes
LT3581HDE#TRPBF 4x3 DFN-14 DE H 05-08-1708 Yes
LT3581IDE#PBF 4x3 DFN-14 DE I 05-08-1708 Yes
LT3581IDE#TRPBF 4x3 DFN-14 DE I 05-08-1708 Yes
LT3581IMSE#PBF MS-16E MSE I 05-08-1667 Yes
LT3581IMSE#TRPBF MS-16E MSE I 05-08-1667 Yes


LT3581 Package Drawing
LT3581 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3581EDE#PBF 4x3 DFN-14 E $3.50 $2.45 Yes
LT3581EDE#TRPBF 4x3 DFN-14 E $2.51 Yes
LT3581EMSE#PBF MS-16E E $3.64 $2.55 Yes
LT3581EMSE#TRPBF MS-16E E $2.61 Yes
LT3581HDE#PBF 4x3 DFN-14 H $4.24 $2.97 Yes
LT3581HDE#TRPBF 4x3 DFN-14 H $3.03 Yes
LT3581IDE#PBF 4x3 DFN-14 I $3.89 $2.72 Yes
LT3581IDE#TRPBF 4x3 DFN-14 I $2.78 Yes
LT3581IMSE#PBF MS-16E I $4.04 $2.83 Yes
LT3581IMSE#TRPBF MS-16E I $2.89 Yes
Buy NowRequest Samples
* 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 Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1424A-A LT3581EMSE Demo Board | VIN= 5V to 10V, VOUT1 = 12V @ 900mA $175.00
DC1424A-B LT3581EMSE Demo Board | VIN= 5V to 12V, VOUT1 = -12V @ 750mA $175.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LT3581HDE#PBF 4x3 DFN-14 H $4.24 $2.97 Yes
LT3581HDE#TRPBF 4x3 DFN-14 H $3.03 Yes
LT3581IDE#PBF 4x3 DFN-14 I $3.89 $2.72 Yes
LT3581IDE#TRPBF 4x3 DFN-14 I $2.78 Yes
LT3581IMSE#PBF MS-16E I $4.04 $2.83 Yes
LT3581IMSE#TRPBF MS-16E I $2.89 Yes
Buy NowRequest Samples
* 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 Linear Technology sales office or authorized distributor.

Applications

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

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Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, 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

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LT3581

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

Design tools for the following parts are available in LTpowerCAD:
LT3581

Technical Support