• 简体中文
• English

LT4321 - PoE Ideal Diode Bridge Controller

The LT®4321 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.

Features 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 Typical Application

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

Demo Boards