LT3575 - Isolated Flyback Converter without an Opto-Coupler

Features

  • 3V to 40V Input Voltage Range
  • 2.5A, 60V Integrated NPN Power Switch
  • Boundary Mode Operation
  • No Transformer Third Winding or Optoisolator Required for Regulation
  • Improved Primary-Side Winding Feedback Load Regulation
  • VOUT Set with Two External Resistors
  • BIAS Pin for Internal Bias Supply and Power NPN Driver
  • Programmable Soft-Start
  • Programmable Power Switch Current Limit
  • Thermally Enhanced 16-Lead TSSOP
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LT3575 Typical Application
LT3575 Typical Application

Description

The LT3575 is a monolithic switching regulator specifically designed for the isolated flyback topology. No third winding or optoisolator is required for regulation. The part senses the isolated output voltage directly from the primary side flyback waveform. A 2.5A, 60V NPN power switch is integrated along with all control logic into a 16-lead TSSOP package.

The LT3575 operates with input supply voltages from 3V to 40V, and can deliver output power up to 14W with no external power switch.The LT3575 utilizes boundary mode operation to provide a small magnetic solution with improved load regulation.

The output voltage is easily set with two external resistors and the transformer turns ratio. Off the shelf transformers are available for many applications.

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
LT3575EFE#PBF TSSOP-16 FE E 05-08-1663 (BA) Yes
LT3575EFE#TRPBF TSSOP-16 FE E 05-08-1663 (BA) Yes
LT3575IFE#PBF TSSOP-16 FE I 05-08-1663 (BA) Yes
LT3575IFE#TRPBF TSSOP-16 FE I 05-08-1663 (BA) Yes


LT3575 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
LT3575EFE#PBF TSSOP-16 E $4.24 $2.97 Yes
LT3575EFE#TRPBF TSSOP-16 E $3.03 Yes
LT3575IFE#PBF TSSOP-16 I $4.67 $3.27 Yes
LT3575IFE#TRPBF TSSOP-16 I $3.33 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
DC1643A LT3575EFE Demo Board | 10V to 28VIN, VOUT = 5V @ Up to 2A $100.00
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
LT3575IFE#PBF TSSOP-16 I $4.67 $3.27 Yes
LT3575IFE#TRPBF TSSOP-16 I $3.33 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

  • Industrial, Automotive and Medical Isolated Power Supplies

Product Notifications

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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:
LT3575

Technical Support