Main Site Documentation

Ethernet magnetics question


#1

Hi guys,

I know this is a little left field but I am designing a board at the moment to use the USBizi and wiznet chip but really scratching my head over a small problem.

I understand that between the wiznet chip and the actual RJ45 jack there needs to be a set of magnetics.

So my question is this:

Where there heck are they?

Do they
a: Come built into the RJ45 Jacks and if so why do none of them say they have them built in?
b: Have to be added as a separate chip between the 2 items and if so why are there so few of them on the market? (Well that I can find anyway…)

Can please someone point out what the heck I am missing as this is driving me quietly mad… I know it is going to be simple and I just can’t see the solution.

Thanks in advance to all,

Kind regards,

Andy


#2

You can get them external to the jack or built in the jack. Most use built in jack as it is smaller and easier but if you are making thousands/millions then external maybe cheaper!


#3

Thanks Gus,

I guess my problem was that I am looking at several major suppliers of RJ45 Jacks and having searched several different ways I needed to sanity check what I was doing as none of them came up that they included magnetics… but then when you look for magnetics there don’t seem to be many…

Thanks again,

//A


#4

Nowadays, they are almost always included inside the RJ45 “filter-jack”.

They sell them at robotshop: http://www.robotshop.com/filter-3.html
(25$ the 5 pack)

They have a lot of choice at digi-key too :slight_smile:

I like the last one used by GHI in their Fez-Connect, with the status leds embedded !


#5

You might see the term “magjack” those have the magnetics built in.


#6

Here is one I have used from Sparkfun:
http://www.sparkfun.com/products/8534


#7

Thanks guys. It was those search terms I was missing. It’s the age old problem that they have a specific name and I just didn’t know it!

Either way, every day is a school day, so thank you all for your help!

Kind regards,

Andy


#8

Using ethernet is not as easy as including the connector. As far as I know the physical layer is not on the chip itself and need an extra IC.