LT3748 - 100V Isolated Flyback Controller
Features
- 5V to 100V Input Voltage Range
- 1.9A Average Gate Drive Source and Sink Current
- Boundary Mode Operation
- No Transformer Third Winding or Opto-Isolator Required for Regulation
- Primary-Side Winding Feedback Load Regulation
- VOUT Set with Two External Resistors
- INTVCC Pin for Control of Gate Driver Voltage
- Programmable Soft Start
- Programmable Undervoltage Lockout
- Available in MSOP Package
AEC-Q100 data available for specific packages
Typical Application
Description
The LT3748 is a switching regulator controller specifically designed for the isolated flyback topology and capable of high power. It drives a low side external N-channel power MOSFET from an internally regulated 7V supply. No third winding or opto-isolator is required for regulation as the part senses the isolated output voltage directly from the primary-side flyback waveform.
The LT3748 utilizes boundary mode to provide a small magnetic solution without compromising load regulation. Operating frequency is set by load current and transformer magnetizing inductance. The gate drive of the LT3748 combined with a suitable external MOSFET allow it to deliver load power up to several tens of watts from input voltages as high as 100V.
The LT3748 is available in a high voltage 16-lead MSOP package with four leads removed.
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 |
|---|---|---|---|---|---|
| LT3748EMS#PBF | MS-16 | MS | E | 05-08-1847 | Yes |
| LT3748EMS#TRPBF | MS-16 | MS | E | 05-08-1847 | Yes |
| LT3748HMS#PBF | MS-16 | MS | H | 05-08-1847 | Yes |
| LT3748HMS#TRPBF | MS-16 | MS | H | 05-08-1847 | Yes |
| LT3748IMS#PBF | MS-16 | MS | I | 05-08-1847 | Yes |
| LT3748IMS#TRPBF | MS-16 | MS | I | 05-08-1847 | Yes |
| LT3748MPMS#PBF | MS-16 | MS | MP | 05-08-1847 | Yes |
| LT3748MPMS#TRPBF | MS-16 | MS | MP | 05-08-1847 | Yes |
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 | |
|---|---|---|---|---|---|---|
| LT3748EMS#PBF | MS-16 | E | $4.46 | $3.12 | Yes | |
| LT3748EMS#TRPBF | MS-16 | E | $3.18 | Yes | ||
| LT3748HMS#PBF | MS-16 | H | $5.66 | $3.71 | Yes | |
| LT3748HMS#TRPBF | MS-16 | H | $3.77 | Yes | ||
| LT3748IMS#PBF | MS-16 | I | $4.93 | $3.45 | Yes | |
| LT3748IMS#TRPBF | MS-16 | I | $3.51 | Yes | ||
| LT3748MPMS#PBF | MS-16 | MP | $13.22 | $9.25 | Yes | |
| LT3748MPMS#TRPBF | MS-16 | MP | $9.31 | Yes | ||
| Buy Now • Request Samples | ||||||
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 |
|---|---|---|---|
| DC1557A | LT3748EMS Isolated Demo Board | 30V Vin 75V; Vout = 12V @ 1A | $175.00 | |
| DC1694B | LT3748EMS Isolated Demo Board | No-Opto Flyback, 22V ≤ VIN ≤ 75V; VOUT = 12V @ 2.5A | $175.00 | |
| DC1860B | LT3748EMS Isolated Demo Board | 10V ≤ Vin ≤ 15V; Vout = 52.5V @ 0.7A | $175.00 | |
| DC1961A | LT8309ES5/LT3748EMS Isolated Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A | $175.00 | |
| Buy Now | |||
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports 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 | |
|---|---|---|---|---|---|---|
| LT3748HMS#PBF | MS-16 | H | $5.66 | $3.71 | Yes | |
| LT3748HMS#TRPBF | MS-16 | H | $3.77 | Yes | ||
| LT3748IMS#PBF | MS-16 | I | $4.93 | $3.45 | Yes | |
| LT3748IMS#TRPBF | MS-16 | I | $3.51 | Yes | ||
| LT3748MPMS#PBF | MS-16 | MP | $13.22 | $9.25 | Yes | |
| LT3748MPMS#TRPBF | MS-16 | MP | $9.31 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Isolated Telecom Converters
- High Power Automotive Supplies
- Isolated Industrial Power Supplies
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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
- LT3748 Demo Circuit - 100V No Opto Isolated Flyback Controller (48V to 12V @ 2A)
- LT3748 Demo Circuit - Automotive Isolated Flyback Controller (6-45V to 5V @ 2A)
- LT8309/LT3748 Demo Circuit - 60W, 12V Output, Isolated Telecom Supply (36-72V to 12V @ 5A)
- LT8309/LT3748 Demo Circuit - 40W, 5V Isolated Telecom Supply (36-72V to 5V @ 8A)
- 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:
LT3748
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-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.
