Datasheet Linear Technology LTC3891

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Design Notes

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  Step-Down Converter Delivers 25A at 12VOUT from Inputs Up to 60V &mdash DN1024
  PDF, 141 Kb, File published: Mar 13, 2012
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  advertisement Step-Down Converter Delivers 25A at 12VOUT from Inputs Up to 60V
  Design Note 1024
  Victor Khasiev
  Introduction
  The LTC В® 3890 (dual outputs) and LTC3891 (single
  output) step-down DC/DC controllers directly accept
  inputs from 4V to 60V. This wide input range covers
  input voltages for single or double battery automotive
  environments, thus eliminating the need for snubbers
  and voltage suppression circuitry typically required to
  protect ICs during load dumps. This range also encompasses 48V telecom applications. If no galvanic isolation
  is required between the input and output voltages, the
  LTC3890 and LTC3891 can replace expensive and bulky
  transformer-based converters. When compared to a
  transformer-based solution, an LTC3890 or LTC3891
  step-down converter increases efficiency, reduces
  power loss in the supply lines, simplifies layout and
  significantly reduces the bill of materials. 5
  30.1k 2
  7 0.1ВµF 8
  29 47pF
  4.7nF 9.76k 13
  30 …

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  Bootstrap Biasing of High Input Voltage Step-Down Controller Increases Converter Efficiency &mdash DN493
  PDF, 71 Kb, File published: Jul 15, 2011
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  Bootstrap Biasing of High Input Voltage Step-Down Controller
  Increases Converter Efficiency
  Design Note 493
  Goran Perica and Victor Khasiev
  Introduction
  High voltage buck DC/DC controllers such as the LTC3890
  (dual output) and LTC3891 (single output) are popular in
  automotive applications due to their extremely wide 4V to
  60V input voltage range, eliminating the need for a snubber and voltage suppression circuitry. These controllers
  are also well suited for 48V telecom applications where
  no galvanic isolation is required.
  In a typical application for these controllers, the IC’s
  supply voltage (INTVCC) is provided by the on-chip LDO.
  This LDO produces 5V from input voltages up to 60V to
  bias control circuitry and provide power FET gate drive.
  Although simple, this built-in biasing scheme can be inefficient. Power losses can be significant in applications
  where the input voltage is consistently high, such as in
  48V telecom applications. Reducing the power losses
  in the bias conversion can increase efficiency and also
  reduce the controller case operating temperature.
  Employing EXTVCC to Improve Efficiency
  One of the attractive features of the LTC3890 and LTC3891
  controllers is the external power input (EXTVCC). This is …

Articles

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  Step-Down Converter Delivers 25A at 12V Output from Inputs Up to 60V &mdash LT Journal
  PDF, 2.2 Mb, File published: Jul 20, 2012
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  Step-Down Converter Delivers 25A at 12V Output from
  Inputs Up to 60V
  Victor Khasiev The LTC3890 (dual outputs) and LTC3891 (single output) step-down DC/DC controllers
  directly accept inputs from 4V to 60V. This wide input range covers input voltages for
  single or double battery automotive environments, eliminating the need for snubbers and
  voltage suppression circuitry typically required to protect ICs during load dumps. This
  range also encompasses 48V telecom applications. If no galvanic isolation is required
  between the input and output voltages, the LTC3890 and LTC3891 can replace expensive
  and bulky transformer-based converters. Compared to a transformer-based solution,
  an LTC3890 or LTC3891 step-down converter increases efficiency, reduces power loss
  in the supply lines, simplifies layout and significantly reduces the bill of materials.
  HIGH EFFICIENCY 2-PHASE
  CONVERTER PRODUCES 12V AT 25A Figure 1 shows the LTC3890 in a 2-phase
  single output step-down converter configuration that delivers 25A at 12V, which
  can be scaled up to 75A by adding more Figure 1. High efficiency
  converter produces 25A at
  12VOUT from inputs up to 60V LTC3890 ICs to increase the number of
  power phases. For lower output current,
  the single-phase LTC3891 can be used.
  Implementing a 2-phase converter simply
  requires tying together the independent
  channel pins of the LTC3890, namely, 30.1k 0.1ВµF 47pF
  4.7nF 9.76k …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Step-Down (Buck) Regulators > Micropower Buck Regulators | High Input Voltage Buck | External Power Switch Buck Controllers
• Space & Harsh Environment > Extended Temperature Plastic (H & MP) > Extended Temperature (H & MP) Switching Regulators