4P20 6
OPERATION
POE OPERATION
Power over Ethernet is a system that allows low powered remote devices to get
power over standard Ethernet wiring. The 4P20 is a POE tap for low power PC/104 and
PC/104-PLUS systems. The 4P20 supplies 11W total of 5V and +- 12V power. This power
is electrically isolated from the power delivered via the Ethernet wiring.
Normally, the 4P20 is put in series with the Ethernet wiring coming from a POE
capable hub and the remote system, with the 4P20s UPSTREAM connector (J2)
connected to the hub, and the DOWNSTREAM connector (J3) connected with a short
CAT5 patch cable to the CPU or other remote PC/104 card.
AUXILIARY INPUT OPERATION
In addition to running from a POE source, the 4P20 can function as an isolated
power supply for a PC/104 stack with and external 18 to 60V power source. If an external
source is supplied to the RAUX input, it has dominance over the POE input, shutting down
the POE input and using the RAUX input exclusively as the power source. This allows dual
sources to coexist, for example battery and POE. Note that the 4P20 can seamlessly
shift from POE power to RAUX power, but the reverse is not true, as the POE system takes
time to go through its detection, classification, and startup phases, when it starts to power
a load.
