LT4321/LT4275 LTPoE++/PoE+/PoE PD Controller TechClips

Power over ethernet is a continuing trend in the Ethernet world. The current IEEE standard allows for up to 25.5W of PD input power. LTPoE++ is Linear Technology's solution to meet the demand for greater power with 38.7W, 52.7W, 70W and 90W power levels.

Heat generated by Power Over Ethernet powered device (PD) is a design issue, especially in tightly sealed weather proof boxes or compact enclosures.  The LT4321 and LT4275 help keep temperatures down by easing thermal design, reducing waste heat, and increasing efficiency.

With limited power available at the input of Power Over Ethernet powered devices (PD), efficiency is crucial for maximizing the PD's available power. The LT4321 ideal diode bridge replaces the traditional input diode bridge of a PD with low Rds(on) MOSFETs. The LT4275 PD controller drives a low Rds(on) hot swap MOSFET of choice instead of an integrated high Rds(on) MOSFET.  These two parts combine to increase efficiency, increase available PD power, and reduce waste heat.