Ethernet Port Lines
Ethernet port of the EM1206 is of 100BaseT type. Onboard electronics of the EM1206 do not include Ethernet magnetics, so magnetic circuitry must be connected externally to pins TX+, TX-, RX+, RX-, and AVCC. The AVCC pin outputs clean 1.8V power for the magnetics circuitry, which is very sensitive to noise. Separate AGND analog ground is also provided. Please, note the following:
The AVCC is an output!
Do not combine AVCC with the VCC (main power) pin. This will apply wrong voltage to the AVCC pin. Doing so appears to cause no immediate permanent damage to the EM1206, but the circuit will not work and the effects of prolonged over-voltage on the AVCC line are not known.
You can use either a standalone magnetics part (such as YCL-PH163112) or an RJ45 connector with integrated magnetics (i.e. YCL-PTC1111-01G). Here is a connection diagram for the YCL-PTC1111-01G jack with integrated magnetics.
Alternatively, you can use the EM1206 in combination with the RJ203 jack/magnetics module. Unique patent-pending design of the RJ203 "tucks" the EM1206 under the RJ203 thus minimizing required host PCB space. For more information see RJ203 documentation (mechanical drawing of the EM1206+RJ203 module combination can be found here).