This is my first ethernet circuit, and I am a noob in differential signal lines. That is why I want to learn with a "simple" circuit.
I use the reference schematics from the LAN9512 USB to Ethernet chip (100 Mb/s).
My question is with the Bob Smith terminator. The reference schematic uses a RJ45 with a transformer and the terminator included. But I want to test an external transformer (next project will be a "simple" Ethernet switch).
So, I checked other reference designs, and I found different variations for the Bob Smith circuit. Some use 51 ohm resistors, others 75 ohm... I am quite confused here.
This is the terminator that I am using. It is the only one that I found that uses resistors on both sides of the transformer (I guess that is to match impedance in both sides of the transformer).
This is my schematic:
What do you think?