Datasheet Linear Technology LTC1871

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Design Notes

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  LTC1871 No RSENSE Controller Is Small and Efficient in Boost, Flyback and SEPIC Applications &mdash DN296
  PDF, 75 Kb, File published: Oct 1, 2002
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  No RSENSE Controller Is Small and Efficient in Boost, Flyback
  and SEPIC Applications
  Design Note 296
  Tick Houk
  Introduction
  The increase in demand for high bandwidth signal processing in telecom systems has driven a corresponding
  increase in demand for space-efficient boost, flyback
  and SEPIC power supplies. The LTC В®1871 addresses
  these specific needs by providing a high performance,
  single-ended current mode DC/DC controller IC in a
  small, 10-lead MSOP package. The LTC1871 is efficient
  and easy to use, mainly due to features such as No
  RSENSE в„ў current mode control, a user-programmable
  operating frequency (50kHz to 1MHz), a strong gate
  driver, programmable undervoltage lockout, synchronization capability and a wide input range (2.5V to 36V). is sensed during the on-time, thereby providing the
  control loop with a “lossless” method of measuring the
  switch current. This technique provides the maximum
  efficiency possible for a single-ended current mode
  converter. It also saves board space and reduces the
  cost of the power supply in applications where the drain
  of the power MOSFET is less than 36V (the absolute
  maximum rating of the SENSE pin). It should be noted
  that the output voltage and maximum output current …

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  2-Phase, Dual Output Synchronous Boost Converter Solves Thermal Problems in Harsh Environments &mdash DN481
  PDF, 78 Kb, File published: Jun 30, 2010
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  2-Phase, Dual Output Synchronous Boost Converter Solves
  Thermal Problems in Harsh Environments – Design Note 481
  Goran Perica
  Introduction
  Boost converters are regularly used in automotive and
  industrial applications to produce higher output voltages
  from lower input voltages. A simple boost converter using a Schottky boost diode (Figure 1) is often sufficient
  for low current applications. However, in high current or
  space-constrained applications, the power dissipated
  by the boost diode can be a problem especially in high
  ambient temperature environments. Heat sinks and fans
  may be needed to keep the circuit cool, resulting in high
  cost and complexity.
  To solve this problem, the Schottky output rectifier can be
  replaced by a synchronous MOSFET rectifier (Figure 2).
  If MOSFETs with very low RDS(ON) are used, the power
  dissipation can be reduced to the point where no heat
  sinks or active cooling is required, thus reducing costs
  and saving space.
  Advantages of Synchronous Rectification
  Consider the power dissipation of the single output circuit
  in Figure 1. The output diode D1 carries 6.7A of RMS
  current to produce 3A of output current from a 5V input. …

Articles

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  The LTC1871 Achieves the Industry's Highest Efficiency for Single-Ended Boost, Flyback and SEPIC Topologies &mdash LT Journal
  PDF, 600 Kb, File published: Sep 1, 2001
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  DESIGN FEATURES The LTC1871 Achieves the Industry’s
  Highest Efficiency for Single-Ended
  Boost, Flyback and SEPIC Topologies
  by Tick Houk
  Introduction
  The LTC1871 is a general-purpose
  DC/DC controller IC optimized for
  use in boost, SEPIC and flyback converter applications. It provides flexible,
  high performance operation in a small
  MS10 package in order to extend the
  range of applications from single-cell,
  lithium-ion battery portable electronics up to high voltage, high power
  telecommunications equipment.
  The LTC1871 is distinguished from
  conventional current mode controllers because the current control loop
  can be closed by sensing the voltage
  drop across the power MOSFET switch
  instead of across a discrete sense
  resistor, as shown in Figure 1a. This
  sensing technique provides the maximum efficiency possible for a
  single-ended, current mode converter.
  For applications where the drain of
  the power MOSFET exceeds 36V, or …

Model Line

Manufacturer's Classification

• Power Management > Switching Regulator > Inverting Regulators | SEPIC Regulators | Flyback, Forward and Isolated Controllers
• Power Management > Switching Regulator > Step-Up (Boost) Regulators > External Power Switch Boost
• Space & Harsh Environment > Extended Temperature Plastic (H & MP) > Extended Temperature (H & MP) Switching Regulators