Datasheet Linear Technology LT1681ISW#PBF

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Design Notes

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  Chip Set Offers Low Cost Alternative to 48V Telecom Modules &mdash DN261
  PDF, 105 Kb, File published: Jul 1, 2001
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  Chip Set Offers Low Cost Alternative to 48V Telecom Modules
  Design Note 261
  Kurk Mathews
  The demand for high performance 48V input telecom
  modules has never been higher. The latest generation
  modules offer high current, high efficiency alternatives
  to traditional low voltage potted supplies. Although these
  drop-in solutions are attractive, their higher cost can
  quickly add up as product volumes increase. Replacing a module with an on-board solution based on the
  new LT®1681/LTC ®1698 chip set significantly reduces
  system cost and takes full advantage of board area,
  minimizing the need to derate output power at elevated
  ambient temperatures. Isolated 48V to 3.3V Supply
  The schematic in Figure 3 presents a complete 36VIN to
  72VIN to 3.3VOUT/20A power supply. Total component
  cost is typically below $30 (50k pcs). The 2-transistor
  forward converter utilizes low voltage primary switches
  and provides for recovery of the transformer’s mutual
  and leakage energy. The LTC1698 secondary controller
  synchronizes with the LT1681 via a small pulse transformer and drives secondary synchronous MOSFETs.
  Efficiency is shown in Figure 2. The LTC1698 includes an
  error amplifier and optocoupler drive buffer, eliminating
  the output feed-forward path and loop compensation …

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Manufacturer's Classification

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

Other Names:

LT1681ISWPBF, LT1681ISW PBF