LT3837

PRODUCTION

Isolated No-Opto Synchronous Flyback Controller

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Overview

  • Senses Output Voltage Directly from Primary Side Winding—No Optoisolator Required
  • Synchronous Driver for High Efficiency
  • Supply Voltage Range 4.5V to 20V
  • Accurate Regulation Without User Trims
  • Programmable Switching Frequency from 50kHz to 250kHz
  • Synchronizable
  • Load Compensation
  • Undervoltage Lockout
  • Available in a Thermally Enhanced 16-Lead TSSOP Package

The LT3837 is an isolated switching regulator controller designed for medium power flyback topologies. A typical application is 10W to 60W with the part powered from a DC supply.

The LT3837 is a current mode controller that regulates an output voltage based on sensing the secondary voltage via a transformer winding during flyback. This allows for tight output regulation without the use of an optoisolator, improving dynamic response and reliability. Synchronous rectification increases converter efficiency and improves output cross regulation in multiple output converters.

The LT3837 operates in forced continuous conduction mode which improves cross regulation in multiple winding applications. Switching frequency is user programmable and can be externally synchronized. The part also has load compensation, undervoltage lockout and soft-start circuitry.

The LT3837 is available in a thermally enhanced 16-pin TSSOP package.

Applications

  • Isolated Medium Power (10W to 60W) Supplies
  • Instrumentation Power Supplies
  • Isolated Medical Supplies
LT3837
Isolated No-Opto Synchronous Flyback Controller
9V –18V to 3.3V at 10A Isolated Converter Efficiency vs Load Current Product Package 1 Regulation vs Load Current
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 4

Design Note 2

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LT3837
LTspice

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.

Evaluation Kits

eval board
schematic 1
DC950A-B

LT3837EFE Demo Board | 9V ≤ VIN ≤ 36V, VOUT: 5V/2A, 3.3V/3A, 2.5V/3A

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Product Details

Demonstration circuit 950A-B is an isolated, 30W multi-output, synchronous flyback converter in 1/8 brick format featuring the LT3837. Output voltage sensing is implemented without the use of opto-coupler, by sensing the voltage across a primary side auxiliary winding. A load compensation circuit is used to compensate for voltage drops caused by load currents. DC950A-B has input voltage range 9V-36V. Demonstration circuit 950A uses a transformer design with tapped secondary winding, to achieve higher efficiency and better cross regulation than is possible with a transformer that uses a separate winding for each output.



eval board
schematic 2
DC1038A-B

LT3837EFE | 9V to 36V input to 5V at 7A Synchronous Flyback Converter

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Product Details

Demonstration circuit 1038A-B is a 35W isolated flyback converter with synchronous rectification and primary-side regulation featuring the LT3837. This circuit was designed to demonstrate the high levels of performance, efficiency, and small solution size attainable using the part in a flyback power supply. It operates at 200kHz and produces a regulated 5V, 7A output from an input voltage range of 9V to 36V. Isolation voltage is 1500VDC.

eval board
schematic 3
DC1038A-C

LT3837EFE | 9V to 36V input to 12V at 3A Synchronous Flyback Converter

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Product Details

Demonstration circuit 1038A-C is a 36W isolated flyback converter with synchronous rectification and primary-side regulation featuring the LT3837. This circuit was designed to demonstrate the high levels of performance, efficiency, and small solution size attainable using the part in a flyback power supply. It operates at 200kHz and produces a regulated 12V, 3A output from an input voltage range of 9V to 36V. Isolation voltage is 1500VDC.

eval board
schematic 4
DC1038A-A

LT3837EFE | 9V to 36V input to 3.3V at 10A Synchronous Flyback Converter

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Product Details

Demonstration circuit 1038A-A is a 33W isolated flyback converter with synchronous rectification and primary-side regulation featuring the LT3837. This circuit was designed to demonstrate the high levels of performance, efficiency, and small solution size attainable using the part in a flyback power supply. It operates at 200kHz and produces a regulated 3.3V, 10A output from an input voltage range of 9V to 36V. Isolation voltage is 1500VDC.
DC950A-B
LT3837EFE Demo Board | 9V ≤ VIN ≤ 36V, VOUT: 5V/2A, 3.3V/3A, 2.5V/3A
DC950A-A - Schematic
DC1038A-B
LT3837EFE | 9V to 36V input to 5V at 7A Synchronous Flyback Converter
DC1038A-B - Schematic
DC1038A-C
LT3837EFE | 9V to 36V input to 12V at 3A Synchronous Flyback Converter
DC1038A-C - Schematic
DC1038A-A
LT3837EFE | 9V to 36V input to 3.3V at 10A Synchronous Flyback Converter
DC1038A-A - Schematic

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