Features and Benefits
- 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
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.
- Industrial, Automotive and Medical Isolated Power Supplies
Product Lifecycle 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)
Demonstration circuit 1643A is an isolated flyback converter featuring LT3575, a monolithic switching regulator specifically designed for the isolated flyback converter with an integrated 2.5A, 60V NPN transistor. The DC1643A is designed for 5V output from a 10V to 28V DC input. The output current capability depends on the input voltage, proper cooling, and the switch voltage stress. The output current is up to 1.4A when the input is higher than 10V, and 2A when the input is higher than 20V but less than 28V. The output current should not be higher than 2.4A for safe operation.
Documentation & Resources
R530 Reliability Data3/26/2018
DC1643A - Demo Manual11/7/2011
48V No-Opto Isolated Applications12/21/2010
Isolated Power Your Way1/21/2014
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:
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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.