Datasheet Linear Technology LT4320HN8-1#PBF

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LT4320

Design Notes

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  Active Bridge Rectifiers Reduce Heat Dissipation within PoE Security Cameras &mdash DN519
  PDF, 106 Kb, File published: Aug 28, 2013
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  Active Bridge Rectifiers Reduce Heat Dissipation within PoE
  Security Cameras – Design Note 519
  Ryan Huff
  Introduction
  Power over Ethernet (PoE) has been embraced by the
  video surveillance industry as a solution to an age-old
  problem: complicated cabling. For instance, a basic,
  traditional fixed-view security camera requires two
  cables: one for power (10W to 15W from a 24V AC
  or 12V DC), and a separate, coax cable for the video
  signal. With PoE, a single Ethernet cable carries both
  video data and power. Everything is simplified. Right?
  Not quite. To meet compatibility with existing systems,
  camera manufacturers must produce PoE-enabled
  cameras that are also compatible with legacy power
  sources—they must accept PoE 37V to 57V DC from
  an RJ-45 jack or 24V AC, +12V DC, or –12V DC from
  an auxiliary power connector.
  The Old Way Loses Power
  Figure 1 shows the power architecture used by many
  PoE camera manufacturers to solve this problem. A
  full-bridge diode rectifier after the auxiliary (old-school)
  input produces positive DC power from either 24V AC, …

Articles

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  Meet Green Standards in 24VAC and 12VAC Lighting Systems: Replace Halogen Bulbs with LEDs Driven by High Power Factor, High Efficiency Converter &mdash LT Journal
  PDF, 4.0 Mb, File published: Oct 9, 2013
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  Meet Green Standards in 24VAC and 12VAC Lighting
  Systems: Replace Halogen Bulbs with LEDs Driven by
  High Power Factor, High Efficiency Converter
  Keith Szolusha LEDs are increasingly used in 24VAC and 12VAC lighting systems as a robust,
  energy efficient and high performance alternative to halogen lamps. Power
  converters that drive the LEDs should have a high power factor (above 90% in order
  to meet generally accepted green standards), should be efficient, use a minimal
  number of components and should run cool. They do not need isolation.
  One solution that meets these requirements combines a rectifier bridge and a
  current-controlled synchronous step-up/
  step-down converter. Specifically, a synchronous 4-switch buck-boost converter
  can be paired with a 4-switch ideal diode rectifier bridge for high power LEDs; lower
  power solutions can use a standard diode
  bridge. Both solutions are shown here.
  The LT3791 60V 4-switch synchronous
  buck-boost controller IC can drive constant current (either DC or pulsating) into PVIN
  24VRMS
  PULSATING 120Hz M5 RIN
  0.003О© M6 CIN
  1ВµF
  50V 51О©
  0.1ВµF TG2
  24VAC …

Model Line

Manufacturer's Classification

• Monitor, Control and Protection > PowerPath Controllers & Ideal Diodes | Ideal Diode Bridge
• Space & Harsh Environment > Extended Temperature Plastic (H & MP) > Extended Temperature (H & MP) Power Management

Other Names:

LT4320HN8-1PBF, LT4320HN8-1 PBF, LT4320HN81#PBF, LT4320HN8 1#PBF