Application Design Center - IP Phone

Circuit Protection of Power over Ethernet (PoE) Ports

Solutions

Design Notes:

Protection Application:

There are two basic ways of providing DC Power over an Ethernet Port. Shown in the top figure is a method known as "phantom power" that puts a common-mode voltage on the Tx and Rx pairs. The lower figure shows the use of the spare pairs fround in the RJ45 connector to provide power.

Solution Description:

The Tx and Rx pairs should be protected using the appropriate Ethernet protection scheme. The DC power port should be protected using the DC Input protection scheme.

Companion Solutions:

None.

Regulatory Issues:

IEEE standard 802.3af, UL 60950 or EN 60950, Telcordia GR-1089 may apply.

Unique Features:

None.

Application Warnings:

None.