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
>
>