RE: detecting a PD disconnection event
Hi Barry
I support Rick's statement here, and so long that we have more than one
way of predicting an unplug - live and let live.
roger
At 10:39 AM 4/27/01 -0700, Rick Brooks wrote:
>
> 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 > >