PC Review


Reply
Thread Tools Rate Thread

Powering a wired `LAN port

 
 
Man-wai Chang
Guest
Posts: n/a
 
      4th Dec 2011

How much current and/or maybe power does a typical gigabit LAN port use?
500mA like USB 2 port?

--
@~@ You have the right to remain silence.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 15 i686) Linux 3.0.8
^ ^ 17:10:02 up 7 days 16:10 0 users load average: 0.00 0.01 0.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
 
Reply With Quote
 
 
 
 
Paul
Guest
Posts: n/a
 
      4th Dec 2011
Man-wai Chang wrote:
>
> 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/...WL-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

 
Reply With Quote
 
 
 
 
Man-wai Chang
Guest
Posts: n/a
 
      5th Dec 2011
>> 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.


Pardon my English. I meant how much current/power is needed to drive a
typical gigabit ethernet port in a hub/switch/router?

--
@~@ You have the right to remain silence.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 15 i686) Linux 3.0.8
^ ^ 17:10:02 up 7 days 16:10 0 users load average: 0.00 0.01 0.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
 
Reply With Quote
 
Paul
Guest
Posts: n/a
 
      5th Dec 2011
Man-wai Chang wrote:
>>> 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.

>
> Pardon my English. I meant how much current/power is needed to drive a
> typical gigabit ethernet port in a hub/switch/router?
>


I looked up 82547GI on the Intel site, and it says

Power dissipation 1.0W (typical)

When I look up the number for a dual port chip (two RJ45 connectors),
the 82571EB product overview says

Active link state 2.8W @ D0 1000 Mbps

So you could say the power might be in the 1 to 1.4W range,
per Ethernet port.

Those numbers are just for NIC chips. If you have an
ADSL modem, cable modem, four port router, switch or hub,
the power could be quite a bit higher on one of those.
For example, my ADSL2+ modem draws enough power, the
wall adapter for it actually runs hot. That means not
only does the modem waste power, but even the wall
adapter isn't very efficient. That modem is in the 10 watt
range, and it would appear the adapter is wasting another
couple watts on top of that. Most of my other wall adapters
run cooler than that.

Paul
 
Reply With Quote
 
Man-wai Chang
Guest
Posts: n/a
 
      5th Dec 2011

Thanks!


> So you could say the power might be in the 1 to 1.4W range,
> per Ethernet port.
>
> Those numbers are just for NIC chips. If you have an
> ADSL modem, cable modem, four port router, switch or hub,
> the power could be quite a bit higher on one of those.


--
@~@ You have the right to remain silence.
/ v \ Simplicity is Beauty! May the Force and farces be with you!
/( _ )\ (Fedora 15 i686) Linux 3.0.8
^ ^ 17:10:02 up 7 days 16:10 0 users load average: 0.00 0.01 0.05
不借貸! 不詐騙! 不援交! 不打交! 不打劫! 不自殺! 請考慮綜援 (CSSA):
http://www.swd.gov.hk/tc/index/site_...sub_addressesa
 
Reply With Quote
 
ting@thsu.org
Guest
Posts: n/a
 
      5th Dec 2011
On Dec 5, 4:37*am, Man-wai Chang <(E-Mail Removed)> wrote:
> Thanks!
>
> > So you could say the power might be in the 1 to 1.4W range,
> > per Ethernet port.

>
> > Those numbers are just for NIC chips. If you have an
> > ADSL modem, cable modem, four port router, switch or hub,
> > the power could be quite a bit higher on one of those.


Note that when no activity is occurring, you will get near zero watts
on the port. That's the nature of transmission protocols; no activity
means no transmission means no power on the wires.
--
// T.Hsu
 
Reply With Quote
 
 
 
Reply

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Missing port types : local port and Standard TCP/IP port programmer_not_admin Windows XP Print / Fax 3 28th Dec 2006 03:08 PM
Wired and Wireless network can't print to wired network printer =?Utf-8?B?RnJhbms=?= Windows XP Networking 0 20th Jul 2006 08:33 PM
Wireless to Wired XP HOME SP2 - Wired cannot access Wireless box =?Utf-8?B?SnVsaWVDcm9tZXI=?= Windows XP Networking 7 4th Jan 2005 07:05 PM
USB001 Virtual printer port vs USB002 Local port vs USB003 Virtual printer port ???? BobLeavitt Windows XP Print / Fax 1 26th Sep 2004 05:12 AM
I2C through PC parallel port, serial port and/or USB port - please help Adam DIY PC 22 29th Jun 2004 05:48 PM


Features
 

Advertising
 

Newsgroups
 


All times are GMT +1. The time now is 09:37 PM.