LT3748
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LT3748

100V Isolated Flyback Controller

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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 Qualified for Automotive Applications
Additional Details
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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.

Applications

  • Isolated Telecom Converters
  • High Power Automotive Supplies
  • Isolated Industrial Power Supplies
  • Military and High Temperature Applications

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Documentation

Part Model Pin/Package Drawing Documentation CAD Symbols, Footprints, and 3D Models
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Product Lifecycle

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Jun 5, 2024

- 24_0003

Epoxy Change from Henkel 8290 to 8290A for MSOP Package (2)

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Feb 4, 2020

- 20_0129

Laser Mark Conversion for 12-Lead MSOP Packages Assembled in ADPG and UTAC

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Apr 18, 2022

- 22_0050

UTAC Thai Limited (UTL) as Alternate Assembly Site for MSOP Packages / Devices

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Oct 11, 2022

- 22_0244

Epoxy Change from Henkel 8290 to 8290A for MSOP Package

Filter by Model

reset

Reset Filters

Part Models

Product Lifecycle

PCN

Jun 5, 2024

- 24_0003

arrow down

Epoxy Change from Henkel 8290 to 8290A for MSOP Package (2)

LT3748EMS#PBF

PRODUCTION

LT3748EMS#TRPBF

PRODUCTION

LT3748HMS#PBF

PRODUCTION

LT3748HMS#TRPBF

PRODUCTION

LT3748IMS#PBF

PRODUCTION

LT3748IMS#TRPBF

PRODUCTION

Feb 4, 2020

- 20_0129

arrow down

Laser Mark Conversion for 12-Lead MSOP Packages Assembled in ADPG and UTAC

LT3748EMS#PBF

PRODUCTION

LT3748EMS#TRPBF

PRODUCTION

LT3748HMS#PBF

PRODUCTION

LT3748HMS#TRPBF

PRODUCTION

LT3748IMS#PBF

PRODUCTION

LT3748IMS#TRPBF

PRODUCTION

LT3748MPMS#PBF

PRODUCTION

LT3748MPMS#TRPBF

PRODUCTION

Apr 18, 2022

- 22_0050

arrow down

UTAC Thai Limited (UTL) as Alternate Assembly Site for MSOP Packages / Devices

LT3748HMS#PBF

PRODUCTION

LT3748HMS#TRPBF

PRODUCTION

LT3748IMS#PBF

PRODUCTION

LT3748IMS#TRPBF

PRODUCTION

Oct 11, 2022

- 22_0244

arrow down

Epoxy Change from Henkel 8290 to 8290A for MSOP Package

Software & Part Ecosystem

Evaluation Kits 4

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DC1961A

LT8309ES5/LT3748EMS Isolated Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A

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DC1961A

LT8309ES5/LT3748EMS Isolated Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A

LT8309ES5/LT3748EMS Isolated Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A

Product Detail

Demonstration circuit 1961A features the LT8309, a secondary synchronous driver in an isolated, no optocoupler, flyback converter. It regulates a 12V, 5A output from a 36V to 72V input source. Output regulation is handled on the primary side by the LT3748, a boundary conduction mode flyback controller which senses output voltage directly from the primary, resulting in a simple flyback schematic with no opto-coupler.


 


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DC1557A

LT3748EMS Isolated Demo Board | 30V VIN  75V; VOUT = 12V @ 1A

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DC1557A

LT3748EMS Isolated Demo Board | 30V VIN  75V; VOUT = 12V @ 1A

LT3748EMS Isolated Demo Board | 30V VIN  75V; VOUT = 12V @ 1A

Product Detail

Demonstration circuit 1557A is an Non-Opto Isolated Flyback Converter featuring LT3748EMS. It is designed for 12V output from a 30V to 75V DC input. The output current is up to 1A. The part senses the isolated output voltage directly from the primary side flyback waveform during the off time of the power switch. No third winding, opto-coupler or signal transformer is required for regulation. A minimum load of approximately 2% of maximum load is required on the output.


The LT3748EMS is a high input voltage isolated flyback controller operating with input supply voltages from 5V to 100V. The LT3748EMS utilizes boundary mode operation to provide a high efficiency, small size solution with improved load regulation of ±5% over the full line, load and temperature ranges.

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DC1694B

LT3748EMS Isolated Demo Board | No-Opto Flyback, 22V ≤ VIN ≤ 75V; VOUT = 12V @ 2.5A

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DC1694B

LT3748EMS Isolated Demo Board | No-Opto Flyback, 22V ≤ VIN ≤ 75V; VOUT = 12V @ 2.5A

LT3748EMS Isolated Demo Board | No-Opto Flyback, 22V ≤ VIN ≤ 75V; VOUT = 12V @ 2.5A

Product Detail

Demonstration circuit 1694B is an isolated flyback converter featuring the LT3748. The demo circuit is designed for a 12V output from a 22V to 75V DC input. The output current is up to 2.5A. The part senses the isolated output voltage directly from the primary side flyback waveform during the off time of the power switch. No third winding, opto-coupler, or signal transformer is required for regulation. A minimum load of approximately 2% of maximum load is required on the output to maintain regulation.

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DC1860B

LT3748EMS Isolated Demo Board | 10V ≤ VIN ≤ 15V; VOUT = 52.5V @ 0.7A

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DC1860B

LT3748EMS Isolated Demo Board | 10V ≤ VIN ≤ 15V; VOUT = 52.5V @ 0.7A

LT3748EMS Isolated Demo Board | 10V ≤ VIN ≤ 15V; VOUT = 52.5V @ 0.7A

Product Detail

Demonstration circuit 1860B is an isolated flyback converter featuring the LT3748. This demo circuit is designed for Power Sourcing Equipment (PSE) applications with a 52.5V output from a 10V to 15V DC input, with nominal input voltage of 12V. The output current is from 0mA to 700mA, and is capable of a maximum short period overload current of 900mA.


The LT3748 is a high input voltage isolated flyback controller operating with input supply voltages from 5V to 100V, and 1.9A average gate drive source and sink current.



Tools & Simulations 1

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.

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