Datasheet Linear Technology LT3952 — Datenblatt

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Konstruktionshinweise

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  3A, 1MHz Buck Mode LED Driver with Integrated Voltage Limiting &mdash DN556
  PDF, 344 Kb, Datei veröffentlicht: Sep 29, 2016
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  3A, 1MHz Buck Mode LED Driver with Integrated
  Voltage Limiting
  Design Note 556
  Matthew Grant
  Introduction
  The LTВ®3952 monolithic LED driver includes a 4A, 60V
  DMOS power switch, excellent for driving high current
  LEDs in buck mode. Among its many features is an
  input current sense amplifier, which can be leveraged
  to provide built-in LED voltage limiting in buck mode. +
  –
  +
  – VIN LED+ –
  – LED+
  VIN R1
  VOUT = 0.06 (1 + R1/R2)
  IVINN IVINCOMP VOUT SW
  CTRL/PWM LT3952 FB
  F02 1.5M OR
  SMALLER LED–
  VOUT = D VIN
  F01 Figure 1. Buck Mode Topology In buck mode, the anode of the LED string (LED+) is
  tied to the input voltage and the converter draws current from the cathode of the string (LED –). In the case …

Artikel

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  Boost-Buck LED Driver Topology for Automotive LEDs Operates with Low Input and Output Ripple (LT3952) &mdash LT Journal
  PDF, 336 Kb, Datei veröffentlicht: Apr 7, 2015
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  Boost-Buck LED Driver Topology for Automotive LEDs
  Operates with Low Input and Output Ripple
  Keith Szolusha Automotive LED drivers often require step-up/step-down DC/DC converters that
  can produce constant current at a voltage stepped up and stepped down from
  a varying input voltage (battery). Another important requirement for automotive
  applications is low EMI, namely, low input and output ripple. EMI requirements
  can be difficult to satisfy, as few of the most commonly used step-up/step-down
  DC/DC converter topologies can operate with both low input and low output
  ripple, while also meeting other requirements. These demands, however, are easily
  met by the unique, patent-pending, boost-buck topology described here.
  This new topology is not the only stepup/step-down topology available. There
  are a number of other topologies that
  can convert a wide-ranging input voltage to a VLED within that range. The most
  commonly used nonisolated step-up/
  step-down LED driver topologies include: 4-switch buck-boost for very
  high power and efficiency The overall size of the combined boostbuck inductors (or coupled inductor) is similar to the single inductor in buck-boost mode. The input ripple
  is similar to a SEPIC, but the output
  ripple is much lower. The inductor size LED– Figure 1. The LT3952 8V–36V input to 6V–18V LED 1A boostbuck LED driver has low input and output ripple with 300:1
  PWM dimming capability at 120Hz and 90% efficiency. There are advantages to each of these
  topologies, but none can produce both
  truly low input and output ripple. Linear
  Technology’s patent-pending “boostbuck” (boost-then-buck-mode) floating
  output LED driver topology features …

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  One LED Driver Is All You Need for Automotive LED Headlight Clusters (LT3795) &mdash LT Journal
  PDF, 762 Kb, Datei veröffentlicht: Jul 7, 2015
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  design features One LED Driver Is All You Need for Automotive LED Headlight
  Clusters
  Keith Szolusha and Kyle Lawrence Low beam headlights, high beam headlights, daytime running lights and signal lights are
  often fashioned together in a single unit or cluster, allowing designers to produce distinctive
  automotive front end looks. LED lighting has found its way into these clusters, distinguishing
  the high end faces of today’s luxury vehicles; but LEDs offer more than just good looks.
  They have a number of technical advantages over competing lighting technologies—notably
  improved efficiency, robustness and lifetime. Despite these advantages, automobile
  lighting designers are challenged by the cost of replacing traditional lamps with LEDs.
  A significant portion of the cost LED
  lighting is driven by the costs of the
  LEDs themselves, thermal management
  assemblies (such as finned metal heat
  sinks) and robust LED driver circuits.
  Traditionally, each LED beam or light
  type would require its own LED driver
  PCB. Costs and complexity can be significantly reduced if a single driver is used to drive multiple LED strings (in
  series) within the lighting cluster.
  A comprehensive, multi-LED-string driver
  must support the high voltages and high
  currents required by high power LED
  strings. It must also deftly handle the
  on/off transitions of some LED strings …

Modellreihe

Herstellerklassifikation

• Power Management > LED Driver ICs > Step-Up (Boost) LED Drivers | Step-Down (Buck) LED Drivers | Buck-Boost LED Drivers | Multitopology LED Driver
• Space & Harsh Environment > Extended Temperature Plastic (H & MP) > Extended Temperature (H & MP) LED Drivers