[802.3_RTPGE] channel definitions ad hoc report and survey - comments to meeting minutes questions
Colleagues,
as I was unfortunately not able to attend
to the San Diego meeting,
I'd like to clarify some misunderstandings
or questions (which I got
from the meeting minutes) concerning
the slides I contributed to:
As there are no "Bosch requirements"
I assume that the Continental
slides from Helge (zinner_01_0712.pdf)
which do not exactly match to
the Daimler answers (buntz_01_0712.pdf)
in all cases: So there were
3 questions in the meeting minutes I'd
like to comment:
1) "Power levels stated are different
from Bosch requirements"
As Helge stated in slide 3 there are
ECU with up to 60W, however
tody the focus is on "smart sensors"
which need much less power - maybe in the
range of 1W...2W (depending also on
how much power the PHY needs).
But to be future prove there should
be the possibility to supply also small
ECUs - for example seat adjustment,
ECUs in the mirror or other remote
positions/faraway locations. For this
ECUs the necessary power will be
higher than for smart sensors, however
I can not tell you exactly which
amount of power they need, but it's
very likely to be between 10W and 25W.
Despite this point there are - to my
knowledge - no fixed defined power levels
for automotive ECUs.
2) "Power surges are “unlikely”
as opposed to Bosch response of “likely”"
Maybe this is based of a misunderstanding
from my side: I interpreted
the question (Will the power system
need to support surge loads (motor start)?)
in the way that the PoE/PoDL system
must be able to supply systems
like the ingnition and starter, which
belong to the most ugly parts of a car
in terms of EMC. This is from my point
of view not the case, because this
would always "kill" the communication,
however, due to the wiring inside
the car there are for sure pulses which
can couple to the data line and
there for there are also requirements
(ISO7637-x) concerning the pulses
on the supply line. Even I could imagine
to energize small motors
(seat/mirror adjustment) via PoE/PoDL,
however this needs adequate
filtering of the supply and there will
be a trade-off point, where the filtering
will be more expensive than a separate
wire.
3) Power fault action ‐> Switch
to safe state (Bosch response :shutdown)
Here from my point of view there is
no mismatch: Shutdown for sure is
a safe state (in most cases ;-)
I hope this clarifies some misunderstandings
which maybe came up
during the meeting...
Regards,
Stefan Buntz
Dr.-Ing. Stefan Buntz
Daimler AG
Group Research & Advanced Engineering
Abt. RD/ESA
HPC 059-U059
Wilhelm-Runge-Strasse 11
89081 Ulm/Germany
Phone +49 (0)7 31 505-2089
Fax +49 (0)7 11 30521 64595
mailto:stefan.buntz@xxxxxxxxxxx
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