Descrete transformers pairs for 100 Mpbs Ethernet

[ricko_uk]

Hi,
because of space constraints I am thinking of using two of these mini SMD transformers instead of a full Ethernet transformer: https://www.coilcraft.com/getmedia/a775ad5d-df75-4a65-939f-1b45403ec9fd/1812trx.pdf

The application is 100 Mpbs and those two transformers have two different inductance. Why two inductance values? What is the practical difference between the two inductance models?

Most importantly, which one is the preferred one for 100 Base-T?

Also, if my understanding is correct, specifically for 10/100 Base-T, I don't need to connect the centre taps, is that correct?

Thank you

[DaJMasta]

If it's for space constraints, why not use a connector with the magnetics integrated?

I'd post the digikey link to RJ45 jacks that are at least 100 base T with integrated magnetics, but it's enormous.  I'm seeing 809 choices, and most of the connectors are only slightly bigger than an ethernet jack without them integrated.

[mikeselectricstuff]

There are plenty of very cheap single-channel ethernet magnetics on LCSC - I used these a while ago where I had a very tight height  requirement.

https://www.lcsc.com/products/Pulse-Transformers-LAN_543.html

The datasheet will usually tell you what speeds they are intended for. the Centre-tap is usually needed for the PHY. The PHY datasheet or appnotes  should tell you what inductance it's designed for
 

[mikeselectricstuff]

If it's for space constraints, why not use a connector with the magnetics integrated?

I'd post the digikey link to RJ45 jacks that are at least 100 base T with integrated magnetics, but it's enormous.  I'm seeing 809 choices, and most of the connectors are only slightly bigger than an ethernet jack without them integrated.

Not all ethernet interfaces have an RJ45 jack ( or not local to where the magnetics need to be)

[ricko_uk]

Thank you both