I don't know how to wire RJ45 connector with magnetics

[sw_guy]

First, yes, this is a duplicate. It seems that "nobody" reads the beginner section.

There are a few variations of RJ45 connectors (with magnets). I am not sure how to connect P1 and P10. I can see that on some connectors P10 is connected to GND and P1 to GND thru 10nF capacitor, but internal wiring (=center tap) is not exactly the same way.

Thanks in advance!

sw guy

Edit: magnets to magnetics 

[ataradov]

There are multiple ways to connect those center taps. It depends on the PHY you are using. You need to look in the datasheet and/or reference schematic for your PHY.

[tooki]

Cross-posting because you didn’t get enough answers fast enough is generally not going to get you any more answers, but will annoy people — for the most part, it’s the same core of people reading and answering all the subforums. If you’re not getting answers, there may be something wrong with your question, like providing too little context or not showing what you’ve done already.

Also, you need to be patient: getting miffed that you haven’t gotten enough responses only 26 hours after posting is ridiculous. Sometimes answers come quickly, sometimes it takes time.

[coromonadalix]

complaint as been made to a mod

[sw_guy]

complaint as been made to a mod

 

[pcprogrammer]

There are multiple ways to connect those center taps. It depends on the PHY you are using. You need to look in the datasheet and/or reference schematic for your PHY.

There is also something to do with POE in combination with the center tabs. Have you searched the net for any schematics where ehternet connectors with integrated magnetics are used?

You might find this interesting to read.

Also as a hint and understandable when English is not your native language, the word "magnets" in the thread title is incorrect and possibly misleading. You might want to change it to "How to connect RJ45 Jack with Integrated Magnetics".

[selcuk]

As suggested, check out the ethernet transceiver's application notes. Some needs termination resistors as well. Connector datasheets don't include that information.

[sw_guy]

>Have you searched the net for any schematics where ehternet connectors with integrated magnetics are used?
I have and I thought it was a quick search to find the answer but it turned out it wasn't. I have a couple of reference circuits but they do not have exactly the same internal wiring.

>You might find this interesting to read.
This was one of pages I found. But I did not get more information out of it.

> word "magnets"
My apologies. Typo corrected.

>As suggested, check out the ethernet transceiver's application notes. Some needs termination resistors as well. Connector datasheets don't include that information.
Ok, so if the answer is to follow PHY then the answer might be rather clear (or not). PHY datasheet was the first document I had and according to the datasheet, center taps  (pins 4 and 5) are connected to GND thru 100nF capacitor. Since the magjack I have has an internal 100nF capacitor the same circuit can be made by connecting P10 to GND. And this is pretty much what I have found from other designs too.

The attached image is the magjack used in the PHY's reference design.

sw guy

[ataradov]

The equivalent connections would be P1 to pins 4+5, and P10 to the ground.

[sw_guy]

>The equivalent connections would be P1 to pins 4+5, and P10 to the ground.

Yes, and that is the initial conclusion I made as well. As per PHY doc, pins 4+5 goes to ground thru 10nF capacitor. Just the the setup is not the same: central taps are grounded first by internal 100nF capacitors and by 10nF external capacitor.

sw guy

[ataradov]

What is your PHY? What 10 nF capacitor you are talking about?

[sw_guy]

The PHY: BCM54210PE
The attached image is taken from the reference circuit. This one has 100nF capacitor (pins 4&5 to ground).

I could make my life easier and order these:
https://www.mouser.fi/ProductDetail/TE-Connectivity/5-2337992-8?qs=l4Gc20tDgJIqFEPxQvwM3w%3D%3D

which is a direct replacement to the MagJack-A70-112.

sw guy

[eb4fbz]

For BCM54210PE (Voltage mode transceiver), P10 must be grounded and P1 left open.

[sw_guy]

For BCM54210PE (Voltage mode transceiver), P10 must be grounded and P1 left open.

Yes. I was right about writing that I got this now. Or... I get both of the topics now: first, I was not able to find an answer how to connect different RJ45 connectors because there is not such a question. The question is how the PHY needs a connector to be wired. And the second question: what is the equivalent wiring for the RJ45 connector I chose to use with the PHY in question. And that is: connecting P10 to ground so that center taps are grounded thru 100nF.
This was definitely about learning something new. Again.

Thanks all!

sw guy