Datasheet Linear Technology LT3781

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  Secondary Side Dual Output Controller Tightly Regulates Two Isolated Outputs &mdash DN1000
  PDF, 90 Kb, File published: Dec 1, 2003
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  advertisement Secondary Side Dual Output Controller Tightly Regulates Two
  Isolated Outputs – Design Note 1000
  Charlie Zhao and Wei Chen
  Introduction
  Many systems with dual output isolated power supplies
  require tight regulation on both outputs. The LTВ®3804
  makes it possible to satisfy this requirement in a space
  saving and efficient circuit.
  The LT3804 is a secondary side dual output controller. It
  contains an error amplifier and an optocoupler driver to
  regulate the first output. It also includes a complete PWM
  controller and dual N-channel MOSFET drivers for the
  second output. The power to the second output is transferred directly from the transformer secondary winding
  without going through the first output stage, thus minimizing the size of the output inductor and capacitor of the
  first output. Accurate output regulation for both outputs is
  assured—even if the power supply’s outputs are far away
  from the actual loads—due to true differential remote
  sensing.
  Dual Output Isolated Power Supply
  Figure 1 shows a dual output high efficiency isolated
  DC/DC power supply with 36V to 72V input range and two
  outputs of 3.3V/15A and 1.8V/15A. The basic power stage
  topology is a 2-switch forward converter with synchronous rectification. The primary side is controlled by the …

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  Multiple Output Isolated Power Supply Achieves High Efficiency with Secondary Side Synchronous Post Regulator &mdash DN299
  PDF, 85 Kb, File published: Nov 1, 2002
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  Multiple Output Isolated Power Supply Achieves High Efficiency with Secondary Side Synchronous Post Regulator
  Design Note 299
  Charlie Zhao and Wei Chen
  Introduction
  The newly released LTВ®3710, a secondary side synchronous post regulator controller, provides tight regulation
  for all outputs of multiple output isolated power supplies. Solutions that use the LT3710 are efficient, use
  minimal space and provide fast transient response. controller uses the LT3781; a current mode 2-switch
  forward controller with built-in MOSFET drivers. On
  the secondary side a synchronous rectifier controller, the LTC1698, provides the voltage feedback for
  the main 3.3V output as well as the gate drive for the
  synchronous MOSFETs. The LT3710 circuit precisely
  regulates the 2.5V output. Total load and line regulation for the 2.5V output is better than 0.2%. From a
  48V input, the overall efficiency is about 87% with full
  load on both outputs. The LT3710 is a voltage mode controller with leading
  edge modulation, programmable current limit and
  dual MOSFET drivers. It generates a tightly regulated
  second output directly from the transformer secondary
  winding, thus minimizing the size of the output inductor
  and capacitor of the main output stage. The use of synchronous MOSFETs significantly improves efficiency,
  making it suitable for low output voltage applications. Conclusion
  The LT3710 is a high efficiency secondary side synchronous post regulator controller that is designed
  to generate a tightly regulated secondary output for
  multiple output isolated power supplies. It can be used …

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Manufacturer's Classification

• Power Management > Switching Regulator > Flyback, Forward and Isolated Controllers