LT3574 - Isolated Flyback Converter Without an Opto-Coupler
Features
- 3V to 40V Input Voltage Range
- 0.65A, 60V Integrated NPN Power Switch
- Boundary Mode Operation
- No Transformer Third Winding or Opto-Isolator 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
- 16-Lead MSOP Package
Typical Application
Description
The LT3574 is a monolithic switching regulator specifically designed for the isolated flyback topology. No third winding or opto-isolator is required for regulation. The part senses the isolated output voltage directly from the primary side flyback waveform. A 0.65A, 60V NPN power switch is integrated along with all control logic into a 16‑lead MSOP package.
The LT3574 operates with input supply voltages from 3V to 40V, and can deliver output power up to 3W with no external power switch. The LT3574 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
For complete and up to date package information and drawings, please refer to our packaging page
MS-16
Order Info
- Part numbers ending in PBF are lead free. Please contact LTC marketing for information on lead based finish parts.
- 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 | Pins | Temp | Price (1-99) | Price (1k)* | RoHS Data |
|---|---|---|---|---|---|---|
| LT3574EMS#PBF | MSOP | 16 | E | $3.94 | $2.76 | View |
| LT3574EMS#TRPBF | MSOP | 16 | E | $2.82 | View | |
| LT3574IMS#PBF | MSOP | 16 | I | $4.46 | $3.12 | View |
| LT3574IMS#TRPBF | MSOP | 16 | I | $3.18 | View | |
| Buy Now • Request Samples | ||||||
Demo Boards
Linear Technology demo boards are offered free of charge to qualified customers. Contact your local sales office or distributor to request 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 |
|---|---|---|---|
| DC1636A | LT3574EMS Demo Board | Isolated Flyback Converter without an Opto-Coupler | $100.00 | |
| Buy Now | |||
Applications
- Industrial, Automotive and Medical Isolated Power Supplies
Simulate
LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.
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 IV
- Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
- Step 3: If LTspice IV 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.
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
