USB Common Mode Choke


I’m laying out my custom carrier board at the moment, and am a little confused regarding the USB3.0 common mode chokes used in the Ixora carrier board. The choke used is the DLW21SN900SQ2L, which has the following equivalent circuit:

My interpretation of this image, is that pads 1 and 2 are connected, and pads 3 and 4 are connected. However, the schematic for the Ixora shows connections between pads 2 and 3, and between 1 and 4:


These connections are obviously reiterated in the Ixora layout:


The Ixora carrier board obviously works as intended, so I’m guessing I’ve just misunderstood the equivalent circuit?

Dear @jars121,

thank you very much for using the Toradex developer community.

You are definitely right, the way this component has been added to the Altium library might be a bit confusing.

Nevertheless, it works because the pins are assigned in the same way in both the schematic and pcb library.

It is basically a different numbering approach but the equivalent circuit and the pcb footprint are perfectly fine.
I hope that I managed to clarify your doubts, please get back to me if you need further details.

Thanks for confirming @diego.tx, that all makes sense; I thought I was going crazy!

Dear @jars121,

not at all! thanks again for your comment, please don’t hesitate to use again the community if you need!