Man-wai Chang said:
How much current and/or maybe power does a typical gigabit LAN port use?
500mA like USB 2 port?
I'm not sure I understand the question.
*******
There is a standard called Power over Ethernet. It's used by a
central piece of equipment, to power Ethernet peripherals. It
might provide more power, than the Ethernet chip inside the
peripheral might need.
http://en.wikipedia.org/wiki/Power_over_ethernet
"The original IEEE 802.3af-2003 PoE standard provides up
to 15.4 W of DC power (minimum 44 V DC and 350 mA) to each device."
Not every piece of Ethernet equipment, pumps DC power down
the Ethernet cable. My little $39.95 four port router,
does not power the Ethernet cables. Plugging in a peripheral
which runs off PoE into my router, would result in the
peripheral being un-powered and non-operational.
You might find things like some Cisco router, with a
PoE power source on each Ethernet port. It's more
likely to be some expensive equipment which provides power.
It is possible to buy devices that pump "phantom" power down
an Ethernet cable. For example, this device set.
ftp://ftp10.dlink.com/pdfs/products/DWL-P200/DWL-P200_ds.pdf
What that does, is allow ordinary ethernet data to travel through
the cable, while at the same time, adding PoE. One adapter box,
inserts 48V @ 400mA into the Ethernet cable. Now, if you did that,
I presume *any* PoE device at the other end would work.
The second adapter they provide, pulls off the PoE power, and converts
it to a more useful lower voltage potential. For example, 12V DC is
used by a lot of surveillance cameras. And other things might benefit
from a 5V DC supply. And so on. Using that kit, means you could
power a surveillance camera, packet based, outside your house and
away from an AC outlet.
But a proper PoE compatible peripheral, wouldn't need the adapter
at the end, but would just draw in the 44V or 48V DC or whatever,
and do internal conversion to a lower DC voltage. Not many silicon
chips could deal directly with the 44V directly.
So the total available power on the PoE cable, is higher than USB, but
it's not directly useful. You could even get a nasty shock from it!
Paul
