RE: Flying Responses
Hi,
From the tests I have done in the lab with the AC coupled diode
prototypes and by using sensitivity analysis on the model of the
AC coupled diode as presented by PowerDsine at Sep. interim we didnt
find a problem concerning the detected pulse shape as function of
the power supply output filter.
The reason is that on any possible EMI filter configuration we will
have low impedance output capacitor (usually ceramic or film)
that exsibits short circuit to the 5uSec recived pulses.
Yair.
> -----Original Message-----
> From: R karam [SMTP:rkaram@xxxxxxxxx]
> Sent: ו, ספטמבר 22, 2000 6:40 PM
> To: Rick Brooks; Robert H Leonowich
> Cc: 'IEEE 802.3 'DTE Power''
> Subject: Flying Responses
>
>
> Hi
>
> Just wondering if the comments about how the supply filter would affect
> the AC pulses path has been analyzed in the Lab, and the same for the
> resistor
> scheme, early on in this game we had a lot of flying assumptions, gut
> feels,
> and
> affection for positions that did not pan out with hard work on the bench.
>
>
> the assumption of a clean supply is a good one, but by the time the power
> travels
> through connectors in a real system, it may not be as clean as we think,
> so I
> would
> say making sure that heavy duty filtering can be placed in series with
> power
> without
> disabling the detection scheme is not a bad idea, and Please let's not
> only
> spice things
> let's lab them.
>
> 2c,
> roger
>
>
> At 07:30 AM 9/22/00 -0700, Rick Brooks wrote:
>
> >
> > Bob,
> > here are my comments on your comments:
> >
> > 3.) Logic side power plane residence of detection implies EMI can leak
> from
> > noisy logic to wire response: The exact same thing is true of the
> 10/100/1000
> > data paths. EMI problems will be dominated by the switching power supply
> rhl:
> > It seems the common-mode EMI blocking of the data path's transformers
> should
> > be different than that from the signature transformer's?
> > rb: the signature transformers pass 100 KHz signals, so the common mode
> > rejection is good, at high clock frequencies
> > routing or filtering might be required. This could be incorporated into
> the
> > drivers.
> >
> > 4.) Approximately 1MHz bandwidth signature pulse signaling precludes
> > aggressive filtering to limit noise emissions response: If you look at
> page
> > 27 of my presentation, the common mode discovery pulse energy is about
> 40 dB
> > down at 1 MHz, the 3 dB point is more like 30 KHz. rhl: To clarify, I
> meant
> > without a bandwidth constraint in series with the power supply, the
> user is
> > free to filter at any corner frequency to eliminate noise from the
> supply
> > when/if that becomes an issue down the road. If the AC pathway must be
> kept
> > clear, that is one more obstacle to aggressively suppressing power
> supply
> > noise.
> > rb: My view is that you can filter the DC power supply where ever you
> want.
> > The diode detection
> > counts on having an output cap on the power supply to provide a low
> impedance
> > path in both directions through the loop.
> >
> > 5.) Conveyance of current use from supply to upper levels (to facilitate
> > network power management) requires crossing the isolation barrier and
> > additional monitoring circuits in the supply response: This is not
> tied to
> > the discovery method. rhl: However, there seems to be an additional cost
> > associated with providing this function in the diode scheme (as
> presented)
> > since the increased cost of the power module with and without this
> function
> > was not given.
> > rb: As you have framed the scheme (PHY based detection, PHY or logic
> > managed), yes you need these (at least some) control signals.
> >
> > That does not have to do with the detection method however, the method
> can be
> > done in the power supply as well.
> > But are you suggesting putting the mgmt in your detector chip or the
> power
> > supply?
> > How do you communicate with your power supply and detector?
> >
> > 7.) Parallel devices may get destroyed at application of higher power
> > response: Can you be more specific about which parallel devices you are
> > talking about? rhl: This attempts to address the devices outlined in Bob
> > Bell's liaison input to us from: TIA TR41.4 Subcommittee on VoIP
> Gateways
> > and Infrastructures
> >
> > "The ISDN system might legitimately have multiple S-Bus devices on the
> same
> > 4-pair cable which terminates using "RJ45"-type connectors. If that
> cable is
> > reused for an 802.3 network, the endpoint might very well respond to the
> > detection scheme within the detection parameters but when power is
> applied,
> > parallel connected surge protectors left over from the ISDN usage might
> > overheat and cause a fire if subjected to the nominal voltage and if the
> > current is not limited correctly."
> >
> > It also can pertain to test equipment that does not appreciably conduct
> at
> > low voltage (<2V) but does at higher voltage (>6V). A higher signature
> > voltage allows these devices to be detected before having 15W of power
> > applied.
> > rb: I doubt if there will be a positive response to the diode detection
> > scheme, if true, this point is moot.
> >
> > 11.) 1uF >54V signature cap in PE is big and expensive response: The
> cost
> > needs to be considered. Also, the cap value can probably be lowered.
> Even so
> > a 1206 part is not that big. rhl: The DTE would appear to need 2 of
> these
> > cap/signature modules for power on signal/spare pair with the diode
> scheme.
> > This is not true on the resistive scheme.
> > rb: I agree with you here.
> > We should probably just pick one pair and be done with it anyway, this
> would
> > mean only one identity networks,
> > and less diodes required.
> >
> >
> > thanks,
> > - Rick
> >
> >
> >
> > -----Original Message----- From: Robert H Leonowich
> > [SMTP:leonowich@xxxxxxxxxx] Sent: Thursday, September 21, 2000 3:43
> PM
> > To: Brooks, Rick [SC5:321:EXCH] Cc: 'IEEE 802.3 'DTE Power''
> > Subject: Re: response to Bob Leonowich's presentation, page 17,
> Sept
> > 2000
> >
> > Hi Rick,
> >
> > Here are some response comments:
> >
> > 3.) Logic side power plane residence of detection implies EMI can leak
> from
> > noisy logic to wire response: The exact same thing is true of the
> 10/100/1000
> > data paths. EMI problems will be dominated by the switching power supply
> rhl:
> > It seems the common-mode EMI blocking of the data path's transformers
> should
> > be different than that from the signature transformer's?
> >
> > 4.) Approximately 1MHz bandwidth signature pulse signaling precludes
> > aggressive filtering to limit noise emissions response: If you look at
> page
> > 27 of my presentation, the common mode discovery pulse energy is about
> 40 dB
> > down at 1 MHz, the 3 dB point is more like 30 KHz. rhl: To clarify, I
> meant
> > without a bandwidth constraint in series with the power supply, the
> user is
> > free to filter at any corner frequency to eliminate noise from the
> supply
> > when/if that becomes an issue down the road. If the AC pathway must be
> kept
> > clear, that is one more obstacle to aggressively suppressing power
> supply
> > noise.
> >
> > 5.) Conveyance of current use from supply to upper levels (to facilitate
> > network power management) requires crossing the isolation barrier and
> > additional monitoring circuits in the supply response: This is not
> tied to
> > the discovery method. rhl: However, there seems to be an additional cost
> > associated with providing this function in the diode scheme (as
> presented)
> > since the increased cost of the power module with and without this
> function
> > was not given.
> >
> >
> >
> > 7.) Parallel devices may get destroyed at application of higher power
> > response: Can you be more specific about which parallel devices you are
> > talking about? rhl: This attempts to address the devices outlined in Bob
> > Bell's liaison input to us from: TIA TR41.4 Subcommittee on VoIP
> Gateways
> > and Infrastructures
> >
> > "The ISDN system might legitimately have multiple S-Bus devices on the
> same
> > 4-pair cable which terminates using "RJ45"-type connectors. If that
> cable is
> > reused for an 802.3 network, the endpoint might very well respond to the
> > detection scheme within the detection parameters but when power is
> applied,
> > parallel connected surge protectors left over from the ISDN usage might
> > overheat and cause a fire if subjected to the nominal voltage and if the
> > current is not limited correctly."
> >
> > It also can pertain to test equipment that does not appreciably conduct
> at
> > low voltage (<2V) but does at higher voltage (>6V). A higher signature
> > voltage allows these devices to be detected before having 15W of power
> > applied.
> >
> > 11.) 1uF >54V signature cap in PE is big and expensive response: The
> cost
> > needs to be considered. Also, the cap value can probably be lowered.
> Even so
> > a 1206 part is not that big. rhl: The DTE would appear to need 2 of
> these
> > cap/signature modules for power on signal/spare pair with the diode
> scheme.
> > This is not true on the resistive scheme.
> >
> > Bob
> >
> >
> >
> > > Rick Brooks wrote: > > Bob, > I'm sorry that I was not at the
> meeting to
> > answer these questions. > Here are my responses to the item numbers on
> your
> > presentation, page 17 > > 1.) Transformer doesn't necessarily provide
> AC/ESD
> > impulse isolation so this > needs to be > tested > > response: >
> ESD was
> > tested informally, but not reported. > Recall that the logic side of
> the
> > transformer has a 100 ohm and a 3300 pf cap > to ground. > This shunts
> the
> > ESD energy that gets through the transformer. > This is much easier
> than on
> > the data lines, since the pulse bandwidth is so > much lower. > > 2.)
> > Strategy implies PHY redesign and consequential re-qualification on new
> >
> > generation > devices with higher pincount to support the needed I/O >
> >
> > response: > My method can be implemented in the PHY, or in the power
> supply,
> > whichever is > more cost effective. > My prototype shows a PHY
> > configuration. > > 3.) Logic side power plane residence of detection
> implies
> > EMI can leak from > noisy logic to wire > > response: > The exact
> same
> > thing is true of the 10/100/1000 data paths. > EMI problems will be
> dominated
> > by the switching power supply > > 4.) Approximately 1MHz bandwidth
> signature
> > pulse signaling precludes > aggressive filtering to > limit noise
> emissions
> > > > response: > If you look at page 27 of my presentation, the common
> mode
> > discovery pulse > energy is about 40 dB down > at 1 MHz, the 3 dB
> point is
> > more like 30 KHz. > > 5.) Conveyance of current use from supply to
> upper
> > levels (to facilitate > network power > management) requires crossing
> the
> > isolation barrier and additional monitoring > circuits in > the supply
> > >
> > response: > This is not tied to the discovery method. > > 6.)
> Longitudinal
> > voltage characterization in terms of <1 volt sensitivity has > not been
> done
> > > > response: > What exact tests are you asking for? > > 7.)
> Parallel
> > devices may get destroyed at application of higher power > > response:
> >
> > Can you be more specific about which parallel devices you are talking
> about?
> > > > 8.) Use of constant signaling and reliance on transformer
> saturation to
> > detect > undercurrent is > very coarse. >10mA signature pulses imply a
> >0.5W
> > maintenance consumption > > response: > The prototype we built uses
> the
> > power supply to detect a minimum load. It > could use transformer
> saturation,
> > if > that is practical, I'm hearing that the magnetics vendors are
> against
> > it. > Again, this is a separate issue from the discovery method. >
> Also,
> > what does the amplitude of the signature pulse have to do with power? >
> When
> > the DTE power is on, and the undercurrent value matters, and the >
> discovery
> > pulses are off. > > 9.) 25 pair bundle interference with asynchronous
> units?
> > > > response: > This is on my list of things to test. > > 10.) Pulse
> > shaping implies expensive immediate implementation > > response: >
> This is
> > true if you use my discrete approach, but why would anybody do that? >
> An
> > integrated IC solution would use multiple current sources, as the PHY's
> do >
> > now. > > 11.) 1uF >54V signature cap in PE is big and expensive > >
> > response: > The cost needs to be considered. Also, the cap value can
> probably
> > be lowered. > Even so a 1206 part is not that big. > > 12.) Extra two
> diode
> > drops Required in PE lowers maximum power delivered to PE > load > >
> > response: > We could use a FET switch instead. All discovery methods,
> except
> > the large > cap, face this problem of removing > the effect of the 100
> to
> > 500 uF cap on the input of the power supply on > discovery. > > any
> > comments? > > thanks, > - Rick
>
>
>