LT3825

PRODUCTION

Isolated No-Opto Synchronous Flyback Controller with Wide Input Supply Range

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Overview

  • Senses Output Voltage Directly from Primary Side Winding—No Opto-Isolator Required
  • Synchronous Driver for High Efficiency
  • Input Voltage Limited Only by External Power Components
  • Accurate Output Regulation without User Trims
  • Switching Frequency from 50kHz to 250kHz
  • Synchronizable
  • Load Compensation
  • Programmable Undervoltage Lockout
  • Available in a Thermally Enhanced 16-Lead TSSOP Package
LT3825
Isolated No-Opto Synchronous Flyback Controller with Wide Input Supply Range
48V to 3.3V at 12A Isolated Supply Efficiency Product Package 1 Regulation
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Documentation

Data Sheet 1

User Guide 6

Design Note 1

Technical Articles 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

Parts Product Life Cycle Description
Oscillators 1
LTC6909
PRODUCTION 1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation
Switching Regulators & Controllers 2
LTM8047
RECOMMENDED FOR NEW DESIGNS 3.1VIN to 32VIN Isolated μModule (Power Module) DC/DC Converter
LTM8048
RECOMMENDED FOR NEW DESIGNS 3.1VIN to 32VIN Isolated μModule (Power Module) DC/DC Converter with LDO Post Regulator
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Tools & Simulations

LTspice 1

Models for the following parts are available in LTspice:

  • LT3825
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
DC1143A

LT3825EFE Demo Board | Synchronous Isolated Flyback, 36V ≤ VIN ≤ 72V, VOUT: 3.3V @ 6A

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Product Details

Demonstration circuit 1143 is a 20W isolated flyback converter with synchronous rectification and primary-side regulation featuring the LT3825. The circuit was designed to demonstrate the high levels of performance, efficiency and small solution size attainable using this part in a flyback power supply. It operates at 250kHz and produces a regulated 3.3V, 6A output from an input voltage range of 36V to 72V: suitable for telecom and other applications. It has a footprint area that is 1.0 inch square. Synchronous rectification helps to attain efficiency exceeding 88%. Isolation voltage is 1500VDC.



eval board
schematic 2
DC950A-A

LT3825EFE Demo Board | Isolated Synchronous Flyback, 36V ≤ VIN ≤ 72V, VOUT: 5V/2A, 3.3V/3A, 2.5V/3A

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Product Details

Demonstration circuit 950A-A is an isolated, 30W multi-output, synchronous flyback converter in 1/8 brick format featuring the LT3825. 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-A has input voltage range 36V-72V and features the LT3825. 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 3
DC894A-A

LT3825EFE Demo Board I Synchronous Flyback Converter, VIN = 36V to 72V, VOUT = 3.3V @ 12A

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Product Details

Demonstration circuit 894A-A is a 36V-72VIN, synchronous flyback converter featuring the LT3825. This circuit was designed specifically to attain a high current, low ripple, synchronously rectified flyback to efficiently power 3.3V loads at up to 12A from a typical telecom input voltage range. This circuit features synchronous rectifier drive outputs, output voltage regulation without the need of an optocoupler, a self-starting architecture and input undervoltage lockout.

eval board
schematic 4
DC894B-C

LT3825EFE Demo Board | Isolated, 36V ≤ VIN ≤ 72V, VOUT = 12V @ 5A

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Product Details

Demonstration circuit 894B-C is a 36V-72Vin, synchronous flyback converter featuring the LT3825. This circuit was designed specifically to attain a high current, low ripple, synchronously rectified flyback to efficiently power 12V loads at up to 5A from a typical telecom input voltage range. This circuit features synchronous rectifier drive outputs, output voltage regulation without the need of an optocoupler, self-starting architecture and input undervoltage lockout.

eval board
schematic 5
DC894C-B

LT3825EFE Isolated Demo Board | Synchronous Flyback Controller, 36V ≤ VIN ≤ 72V; VOUT = 5V @ 8A

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Product Details

Demonstration circuit 894C-B is a 36V-72Vin, synchronous flyback converter featuring the LT3825. The circuit was designed specifically to attain a high current, low ripple, synchronously rectified flyback to efficiently power 5.0V loads at up to 8A from a typical telecom input voltage range.

eval board
schematic 6
DC894C-C

LT3825EFE Isolated Demo Board | Synchronous No Opto Flyback Controller, 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A

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Product Details

Demonstration circuit 894C-C is a 36V-72VIN, synchronous flyback converter featuring the LT3825. This circuit was designed specifically to attain a high current, low ripple, synchronously rectified flyback to efficiently power 12V loads at up to 5A from a typical telecom input voltage range. This circuit features synchronous rectifier drive outputs, output voltage regulation without the need of an optocoupler, self-starting architecture and input undervoltage lockout.
DC1143A
LT3825EFE Demo Board | Synchronous Isolated Flyback, 36V ≤ VIN ≤ 72V, VOUT: 3.3V @ 6A
DC1143A - Schematic
DC950A-A
LT3825EFE Demo Board | Isolated Synchronous Flyback, 36V ≤ VIN ≤ 72V, VOUT: 5V/2A, 3.3V/3A, 2.5V/3A
DC950A-A - Schematic
DC894A-A
LT3825EFE Demo Board I Synchronous Flyback Converter, VIN = 36V to 72V, VOUT = 3.3V @ 12A
DC894A-A - Schematic
DC894B-C
LT3825EFE Demo Board | Isolated, 36V ≤ VIN ≤ 72V, VOUT = 12V @ 5A
DC894B-B - Schematic
DC894C-B
LT3825EFE Isolated Demo Board | Synchronous Flyback Controller, 36V ≤ VIN ≤ 72V; VOUT = 5V @ 8A
DC894C - Schematic
DC894C-C
LT3825EFE Isolated Demo Board | Synchronous No Opto Flyback Controller, 36V ≤ VIN ≤ 72V; VOUT = 12V @ 5A
DC894C - Schematic

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