LTC4263 Datasheet, PDF (20/24 Pages) Linear Technology – Single IEEE 802.3af Compliant PSE Controller with Internal Switch

LTC4263
APPLICATIONS INFORMATION
Isolation
The IEEE 802.3af standard requires Ethernet ports to be
electrically isolated from all other conductors that are user
accessible. This includes the metal chassis, other connec-
tors, and the AC power line. Environment A isolation is
the most common and applies to wiring within a single
building serviced by a single AC power system. For this
type of application, the PSE isolation requirement can be
met with the use of a single, isolated 48V supply powering
several LTC4263 ports. Environment B, the stricter isola-
tion requirement, is for networks that cross an AC power
distribution boundary. In this case, electrical isolation
must be maintained between each port in the PSE. The
LTC4263 can be used to build a multi-port Environment B
PSE by powering each LTC4263 from a separate, isolated
48V supply. In all PSE applications, there should be no
user accessible connections to the LTC4263 other than
the RJ-45 port.
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