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FW: DTE Power Magnetics and Connector Questions


This message was received on Tuesday and is in answer by FCI to the
questions presented to the connector and magnetics manufacturers by our


Steven B. Carlson
Co-Chair, ESTA Control Protocols Working Group
Chair, ESTA ACN Task Group
Chair, IEEE 802.3 DTE Power via MDI Study
High Speed Design, Inc.
11929 NW Old Quarry Road
Portland, OR 97229
FAX 503.626.4206

-----Original Message-----
From: Belopolsky, Yakov [mailto:BelopoY@xxxxxxxxxxxxx]
Sent: Tuesday, January 18, 2000 7:42 AM
To: 'Steve Carlson'
Cc: Belopolsky, Yakov; Spickler, John M; Huff, Lisa A; Ed Cady
Subject: RE: DTE Power Magnetics and Connector Questions

Hello Steve,

        Ed Cady asked me to respond to your questions, since I am a member
of ISO group developing
 modular jack standards and corresponding test methods. Also, I am involved
in development of
connectors with integrated magnetics.
Some of the answers may require additional explanations and could be better
covered via teleconference/meeting,
some of the answers I do not know.

First of all,  the modular connectors covered by IEC/ISO 60603-7 do not have
any magnetic components,
Such magnetic components, when included in series with signal conductors
(inside connectors) change all
electrical characteristics and reduce current carrying capacity.
Consider that a typical cylindrical Modular jack contact is 0.018 " dia,
while the magnetic wire diameter is 0.004"
Modular connectors with magnetic components (NETJACKs) are not subject to
IEC/ISO 60603-7

Alan 1. The current rating  is expressed by a derating curve e.g 1.8A @ 25
deg C, 1A @ 55 degC
    All pins connected together in series are tested using 1A current.
However the latter is not a current rating

Alan 2. The modular jack is considered always "live"
    The durability is tested without the voltage between jack and plug
    Two durability levels are applicable 750 and 2500 cycles
 There is no enough information to answer in generic terms to Alan's
With a central battery (48V) and jack telephone wire load of 175 ohm, the
plugs and jacks will meet FCC rules part F (250 cycles). The failure
criteria is plating integrity.
The IEC standards do not use plating integrity but a contact resistance;
under such conditions
 500 to 750 cycles can be met.
AT&T has conducted a classic study for telephone connectors a very long time
gold plated 50 microin to support the adoption of FCC regulations -250

Alan 1,2,3 - I think it is a well formulated set of requirements
  (Once again, the LAN magnetics dramatically reduce the CCC of connector
The climatic conditions per 60360-7 are -40 to +70, electrical tests are
conducted @ 20 deg C
There is no agreement on the Maximum operating temperature.
The Curie temperatures of the magnetic cores allowed are 120 dec C minimum.

Scott 1 -Transformer no data
Scott 2 - for LAN magnetics CCC is 0.050 A maximum with saturation tests
conducted @ 8 mA
Scott 3 This is a very astute observation: 1500 V limits the dia of wire
since the coil inductance
is given , so the size of core
Scott 4 Yes , very much so - CCC of the integrated magnetics at least 5
times less than connectors
without magnetics.  HOWEVER, for a simple transformer-less circuits one can
use high conductivity
wire (as oppose to spring connector contacts) that would approximate the
connector without magnetics.

Scott 5. It is a good idea, but most of the known micromini transformers use
simple toroids

Scott 1 Connector
1. FCC regulated geometry does not allow for 1st make last brake.
The current rating see ALAN 1

2. Scott 2
    In principle, the voltage causing the spark or corona discharges also
would affect the number
of insertions.  YES the number of pins would affect the break rating

3. Scott 3
The current rating for each pin is expressed by a derating curve e.g 2.2 @ 0
deg C,
1.8A @ 25 deg C, 1A @ 55 deg C, 0.2 @ 70 deg C

 4. Scott 4  All pins connected in series. MAx temp rise 30 deg above

5.  Scott 5 Please see Alan 2. No information on the current

Scott 6.   20 mOhm
Scott 7    Should not exceed 40 mOhm after environmental exposure

Scott 8   Negligible change if MATED connectors are heated to 70 deg C
 If UNMATED connectors are exposed it would increase up to 40 mOhm

Scott 9   Typically it is within +/- 30 %
Scott 10  No data

Scott  11.  ABSOLUTELY. The very critical issue. The contact force and
wiping action would reduce
the contact resistance. But it would only decline to the certain level until
the plating finish is
broken, then it may increase. If left unmated at this stage the contact
resistance would increase.

Best regards

Yakov  Belopolsky
tel. 717-767-8040
fax 717-767-8003
e-mail belopoy@xxxxxxxxxxxxx
e-mail ybelopolsky@xxxxxxxxxxxxxx

-----Original Message-----
From: Steve Carlson [ mailto:scarlson@xxxxxxxxxxxxx
<mailto:scarlson@xxxxxxxxxxxxx> ]
Sent: Tuesday, January 04, 2000 11:59 AM
To: etparson@xxxxxxxxxxxxxxxxxxx; sellsworth@xxxxxxxxxxx;
henryhinrichs@xxxxxxxxxxxx; Ed Cady
Subject: DTE Power Magnetics and Connector Questions


Due to an e-mail error this did not get sent several weeks ago.

>From Alan Flatman:

1.  what is the maximum dc current supportable by each pin of the IEC
60603-7 connector (i.e. RJ-45), assuming that multiple pins are carrying
the same current? Please state environmental temperature, if applicable.

2.  what is the impact of the above to the number of insertions supported
over life for the IEC 60603-7 connector when current is:
      a) only carried when connectors are mated and
      b) carried when mating and de-mating connectors?

I attended a European standards meeting in London last week, which was a
good opportunity to raise the question of current and voltage capacity of
the modular connector (RJ-45). The group concerned was CENELEC TC215 WG1,
which is responsible for structured cabling. 5 connector manufacturers and
2 test houses were represented at the meeting.

Working figures of 50 Vdc and 250mA per pin were agreed at a temperature of
20degC. Please note that these are STRAWMAN values which require
confirmation by manufacturers. I would like you to consider these as
initial input to the development of a suitable remote powering scheme. In
return, I require the following information which will enable manufacturers
to conduct validation:

1.  Load reactance: we need to understand the nature of the load in terms
of inductance/capacitance. This will determine the maximum current capacity
per pin and contact life (number of insertions).

2.  Make/break current: intelligent power circuits will probably eliminate
or reduce the current when making connector contact, but will this be the
case for breaking? This is quite important.

3.  Temperature range: connector manufacturers intent to specify
performance for -10 to +40degC. Depending on the load reactance, this may
not change the current capacity. Is this sufficient?

>From Scott Burton:

Transformer - assuming 40C maximum ambient
1/What is the maximum tolerable current imbalance?
2/What is the maximum current carrying capability, given the wire guage
and the allowable temperature rise of the component?
3/Is the 1500VAC dielectric strength requirement a significant constraint
to the design of a transformer to carry power?
4/Will the new integrated connector/transformer products present even
more of a challenge with respect to the current-carrying capacity of the
transformer (and connector for that matter)?
5/Is there some clever way to increase the DC current capability of the
transformer by somehow using a gapped core, or a distributed gap core
material, without excessively impacting the leakage inductance/coupling etc?

Connector - assuming 40C maximum ambient and 60VDC maximum
between any two pins
1/What is the break current rating of the connector?
2/Would this break rating be a function of the number of pins conducting
power-level currents?
3/One spec indicated a current rating of 1.5A @ 25C derated to 0.2A @ 70C.
Would this be the standard industry rating (if there is such a thing) for
style of connector?
4/How many of the 8 pins are assumed to be conductiing this rated current?
5/What current is assumed for the durability (# of mating cycles)
What is the relationship between connector current and durability?
6/What is the initial contact resistance?
7/How much would contact resistance vary with time?
8/How much would it vary with temperature?
9/How much variation would there be between contacts in a given connector?
10/Would contact resistance variations tend to increase or decrease if the
contacts were conducting significant (say 50% of rated) current?
11/Does the mechanical wiping action of the contacts when mating help to
control the contact resistance, particularly in harsh environments?


Steven B. Carlson
Co-Chair, ESTA Control Protocols Working Group
Chair, ESTA ACN Task Group
Chair, IEEE 802.3 DTE Power via MDI Study
High Speed Design, Inc.
11929 NW Old Quarry Road
Portland, OR 97229
FAX 503.626.4206