Overview

Features and Benefits

  • Reduces Heat, Eliminates Thermal Design Problems
  • Maximizes Power Efficiency
  • Less than 800μA Quiescent Operating Current
  • Fully Compatible with IEEE 802.3 Detection and Classification
  • IEEE 802.3 Compliant When Paired with a Powered Device (PD) Controller
  • Works with 2-Pair and 4-Pair PoE Applications
  • Compatible with PoE, PoE+, and LTPoE++
  • 100V Absolute Maximum Voltage
  • H-Grade Version Operates Up to 125°C
  • 16-Lead 4mm × 4mm QFN Package

Product Details

The LT4321 is a dual ideal diode bridge controller that enables a Power over Ethernet (PoE) powered device (PD) to receive power in either voltage polarity from RJ-45 data pairs, spare pairs, or both. The LT4321 and eight N-channel MOSFETs replace the eight diodes in a passive PoE rectifier bridge. The LT4321 eases thermal design and increases delivered power.

An internal charge pump allows an all-NMOS bridge eliminating larger and more costly PMOS switches. The LT4321 works with 2-pair and 4-pair applications. High impedance input sense pins prevent reverse current on unused pairs. If the power source fails or is shorted, a fast turn-off minimizes reverse current transients. Unlike discrete ideal bridge solutions, the LT4321 will operate through transients without enabling the MOSFETs on unpowered pairs.

Applications

  • PoE/PoE+/ LTPoE++ Powered Devices
  • DC Polarity Correction and Ideal Diode-ORing of Telecom Supplies

Product Lifecycle icon-recommended Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits (17)

Documentation & Resources

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  • Data Sheets (1)
  • Reliability Data (1)
  • User Guides (15)
  • Product Selector Card (1)
  • Product Selection Guide (1)
  • Videos (2)
  • Press Releases (1)
  • Technical Articles (2)
  • User Guides

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    Product Recommendations

    LT4321 Companion Parts

    Recommended Related Parts

    Design Resources

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    Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.