FW: [SI-LIST] : Contact Current Rating ?
Ellis, John R (EllisJR@bergelect.com)
Fri, 22 May 1998 10:17:33 -0500
> At BERG Contact Current Rating is that DC current which raises the ambient
> temperature by 30C.
> A typical test will take a 200 position connector and wire all of the
> contacts in series. The current is then slowly raised until the
> temperature reaches ambient + 30C. This current value is our published
> contact current rating. This test assumes as a worst case that all
> contacts are carrying the rated current.
> John Ellis
> Berg Electronics
> From: Dennis Tomlinson[SMTP:email@example.com]
> Sent: Friday, May 22, 1998 9:50AM
> To: si-list@silab.Eng.Sun.COM
> Subject: Re: [SI-LIST] : Contact Current Rating ?
> WonSae Sim wrote:
> > Hello, SI Experts
> > I,m concerning how much power pin have to be assigned to meet the power
> > requirement of a card. "Contact current rating" of the catalog of a
> > connector is the only clue for me to decide the number of power pin in
> > the connector.
> > Assume the power requirement of the card is 50 watts, supply voltage 5
> > volts and the contact current rating 1 A. Then 10 power pin pairs (VCC,
> > GND) are enough?
> > Could anyone tell me the meaning of "Contact Current Rating" and how to
> > meet power requirement of the card?
> > Thanks in advance
> > --
> > WonSae Sim
> > Senior Engineer
> > Computer Division, ETRI
> > 161 Gajong-Dong Yusong-Gu, Teajon, 305-350, R.O.KOREA
> > +82-42-860-4827 (V), +82-42-860-6645 (Fax)
> I didn't have a good definition for you, but having the internet at my
> disposal, I searched on "contact current rating" and found:
> 1. A vendor who defines it as a "test condition",
> 2. Another vendor who defines it as a max DC current,
> 3. Another vendor who defines it as the current required to
> cause a 20 mV drop,
> 4. Another vendor who defines it as a "nominal condition", and
> 5. Another who defines it as the current required to
> cause a 3 mV DC drop.
> Most vendors give both AC and DC ratings, with the DC
> being by far the lower. Some don't mention AC or DC.
> From this scant data, I would conclude that there is no single
> definition for "contact current rating".
> I wanted to make a comment about the SI requirements when
> passing high speed signals through a connector. It is desirable
> to have as many interconnects carrying power as you have
> high speed signals. It is also desirable to physically assign signal
> and power interconnects in a checkerboard type arrangement.
> It is my experience that once you have allocated the proper
> amount of power interconnects for SI concerns, you have
> likely satisfied your DC power requirements as well.
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