RE: detecting a PD disconnection event
I believe the claims in the patent are very specific (that's
probably why it was granted). It is for sensing loss of
current on a networking cable to see if something has been
disconnected. Unfortunately this is the very specific case we are
working with, so it seem alternative solutions would be wise.
\Paul
At 12:06 PM 4/27/2001, Bachand, Jerry wrote:
Rick and group,
I still prefer 1a.
Since detecting a minimum current is such a basic and obvious means
to
detect a disconnect, I don't think anyone could even think of
suing. (Not
even Lucent or Avaya.) ;-)
This means of detecting a disconnect has been in use for over 100yrs
by
telephone companies, worldwide, to detect the telephone on-hook
condition.
However, I have no problem with other means, as you mentioned, as long
as
the minimum current method can still be used.
Please keep in mind, eventually there will be many other devices powered
by
the Ethernet, simple might give us more flexibility in the future.
Regards
Jerry
Gerard E.
(Jerry) Bachand
Avaya Inc.
300 Baker Avenue, Suite 100
Concord, MA 01742
(978) 318-6402 Voice
(978) 318-6402 Fax
<gbachand@xxxxxxxxx>
Formerly:
Enterprise Networks Group
("Cajun" LAN Systems)
of Lucent Technologies
-----Original Message-----
From: Rick Brooks
[mailto:ribrooks@xxxxxxxxxxxxxxxxxx]
Sent: Friday, April 27, 2001 1:40 PM
To: Barry Male
Cc: stds-802-3-pwrviamdi@xxxxxxxx
Subject: RE: detecting a PD disconnection event
Barry,
1a) was all of our favorites until Geoff's recent email regarding a
patent
issue.
It may turn out that other methods are more cost effective when
considered
globally.
My proposal is that more than one method could be used, not just the
one
that we have been assuming.
My view is that we must at least consider alternative methods that do
not
use DC current sensing.
thanks,
- Rick
-----Original
Message-----
From: Barry Male [SMTP:male@xxxxxxxxxxxxxxxxxxxxxx]
Sent: Friday, April 27, 2001 10:29 AM
To: Brooks, Rick [SC5:321:EXCH]
Cc: stds-802-3-pwrviamdi@xxxxxxxx
Subject: Re: detecting a PD
disconnection event
Rick,
My
preference is 1a.
Have the
PSE disconnect if the AVERAGE value of load current is less
than
10mA for a sample period of some time (say 100mSec)
This
averaging produces a robust detection method from the
standpoint of
system noise.
Thanks
Barry
_________________________________________________________________
Barry
Male
Senior Principal IC
Designer Internet:
barry_male@xxxxxx
Power Management
Products
NH Phone: 603.429.8705
Texas
Instruments
CT Phone: 860.844.8183
7 Continental
Blvd.
NH FAX : 603.424.3460
Merrimack, NH 03054-0399
USA CT FAX :
860.844.8806
On Fri, 27
Apr 2001, Rick Brooks wrote:
> Just
to start up another discussion, I wanted to find out how many
people
> would support
> the following concept for detecting when a PD receiving power
becomes
> disconnected.
>
> the concept:
>
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>
> 1) The PSE is responsible for detecting when a PD receiving DTE
power
> becomes disconnected.
> If that event occurs, the PSE must turn off the power within some
time
frame
> (100ms to 500ms ballpark?)
>
> 2) The PSE may use any of the following methods to detect this
PD
disconnect
> event.
>
> a) the DC load current drop
below "X" ma (10ma?)
>
> b) the ethernet link has dropped
out
>
> c) another proven method
(pending discussion and feasibility proof)
>
some suggestions:
>
1) the AC probing circuit detects when the AC load changes
> (opens)
>
2) the PD modulation heartbeat current ceases
>
3) the PD response to a given PSE code is wrong or absent
>
4) other ideas
>
>
$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>
>
> Please voice your opinions on this concept.
> The motivation here is to lower the cost of delivering DTE power.
>
> thanks,
> - Rick
>
>