Ethernet Port Lines

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The EM500 has a 10/100BaseT Ethernet port. The onboard electronics of the EM500 do not include Ethernet magnetics, so magnetics circuitry must be connected externally to pins TX+, TX-, RX+, RX-, and AVCC. The AVCC pin outputs clean power for the magnetics circuitry, which is very sensitive to noise.

Please, note the following:

The AVCC is an output!

Do not combine the AVCC with the VCC (main power) pin.

You can use either a standalone magnetics part, or an RJ45 jack with integrated magnetics (recommended). Here is a circuit diagram based on the UDE RT7-114A1A1A part:

 

em500_ether

 

It is important to make the PCB wire connections between the pins of the EM500 and RJ45 jack (magnetics circuitry) as short as possible. Making the wires too long may cause the noise level generated by your PCB surpass the maximum radiated emission limits stipulated by FCC/CE regulations. Additionally, longer Ethernet lines on the PCB will make Ethernet operation less stable.

Note that the circuit above shows an RJ45 jack with two LEDs. Further information on the use of these LEDs can be found in the LED Lines topic.