Alternative Ethernet port for 4.1 - internal resistors?

[SteveCS]

Hi

I see the Ethernet kit for the 4.1 Teensy uses a Cetus J1B1211CCD Ethernet socket.

The socket I am designing onto my own PCB does not have the internal 75R resistors that the Cetus J1B1211CCD shows on it's datasheet.
Is that going to cause me issues? I can't use the Cetus J1B1211CCD, as it's too deep for my PCB and I cannot find another one that fits.

I am (hoping) to use: https://www.digikey.co.uk/en/produc.../2258872?s=N4IgTCBcDaIKwBYAMA2OBmdBaAjCAugL5A

It's unshielded. Are the resistors part of the shielding?

Any help gratefully received!

 

[PaulStoffregen]

That part appears to be just an ordinary socket and LEDs, without any magnetic coupling parts. You will need to add a separate ethernet transformer.

 

[SteveCS]

OK, thanks Paul. Could have come unstuck there then.
I think I will have to find a different part then. The footprint of the Cetus J1B1211CCD is too deep for my PCB.
Hmm!

Thanks for the advice

 

[PaulStoffregen]

Maybe someone will recommend a smaller magjack, but I personally have not seen any which are significantly smaller. The extra space compared to just a plain no-magnetics RJ45 jack is used to hold 4 or 5 little toroid transformers. That magnetic coupling is required for ethernet. If you don't have it inside the connector, you'll need to make room for it somewhere else on your PCB.

Here is an ethernet shield I designed for Teensy 3.6, which used a plain RJ45 connector and a separate ethernet transformer. If you look closely at the full size photo you can probably see the part number on the transformer. Those Pulse brand parts aren't cheap, but they come with nice documentation.



Only about 90 of these were ever made, back in 2016, all of them hand soldered by me and Erin (aka, "Soldering Goddess"). Maybe you can find a smaller ethernet transformer. The one in this photo is just a part I bought from Digikey (back in those days when it was easy to find and buy pretty much any electronic parts).