Datasheet Linear Technology LT3744 — Datenblatt

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  20A LED Driver with Accurate ±3% Full Scale Current Sensing Adapts to Multitude of Applications &mdash LT Journal
  PDF, 2.3 Mb, Datei veröffentlicht: Apr 14, 2016
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  May 2016 I N T H I S I S S U E multi-output clock
  synthesizer with integrated
  VCO and low jitter 12 negative current-reference
  linear regulator 20 Volume 26 Number 2 20A LED Driver with Accurate В±3%
  Full Scale Current Sensing Adapts to
  Multitude of Applications
  Josh Caldwell and Walker Bai load sharing for three or
  four supplies with unequal
  voltages 26 monolithic SEPIC/boost
  regulators with wide VIN
  range, high efficiency,
  and power-on reset and
  watchdog timers 28 Rapidly evolving LED lighting applications are replacing nearly
  all traditional forms of illumination. As this transformation
  accelerates, power requirements for LED drivers increase,
  with higher currents making it more challenging to maintain
  current sensing accuracy without sacrificing efficiency. LED
  drivers must do this while managing current delivery to
  multiple independent LED loads at high speeds, and be able
  to connect parallel drivers with accurate current sharing.
  Some high power LEDs have unique mechanical and
  electrical considerations, where the anode is electrically
  tied to the thermally conducting backtab. In a traditional …

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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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  Can't Find the Right Synchronous Boost LED Driver? Use a Synchronous Buck Converter Instead: Boost Mode Topology Drives 25V, 3A LEDs from 12V &mdash LT Journal
  PDF, 252 Kb, Datei veröffentlicht: Apr 7, 2015
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  Can’t Find the Right Synchronous Boost LED Driver?
  Use a Synchronous Buck Converter Instead:
  Boost Mode Topology Drives 25V, 3A LEDs from 12V
  Keith Szolusha Synchronous buck converter drivers are commonly used when the current required for
  high power LEDs, such as 10A–40A projector LEDs, would overstress the components
  in a nonsynchronous converter. Synchronous rectification limits power losses and thermal
  rise due to high current in the converter switches. Synchronous rectification can offer the
  same benefits in high power step-up (boost) LED drivers—even with 1A to 3A LEDs. In
  contrast to a buck converter, the peak switch current of a boost can be much higher than
  the LED current, especially when output power is high and the input voltage is low.
  For instance, take the LT3744 40V synchronous buck LED driver, which is designed
  to drive high current LEDs for projectors.
  It features a versatile, floating VEE output
  that allows it to be used in both high
  current buck applications and positive-tonegative (buck-boost) topologies where There are a number of situations where a
  synchronous boost LED driver is not available for a particular application. For some
  of these cases, a synchronous buck LED
  driver IC can be used, but instead of operating as a step-down converter, it operates
  as a step-up, or boost mode* LED driver. Figure 1. Boost mode 9V–16V input to 25V, 3A LED driver with 98% efficiency
  VIN
  9V TO 16V
  VIN SGND 200k TG EN/UVLO EN/UVLO 1ВµF
  25V …

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• Power Management > LED Driver ICs > Step-Down (Buck) LED Drivers