MSP432E401Y: POE circuitry

Hi,

You refer the below EVM Board, right?

https://www.ti.com/tool/MSP-EXP432E401Y

Does this issue occur on all boards?

Thanks!

Best Regards

Johnson

Correct that is the EVM Board I am using and yes t's happening on all boards.

Hi,

I think your board's Ethernet function is normal sometimes, indicating that the schematic should normal.

You can check whether the layout is good, and you can refer the EVM board, the differential signal is of equal length, and need keep the impedance is matched.

Thanks!

Best Regards

Johnson

Hi Johnson,

I would definitely look into impedance matching on the differential traces, that could explain the loss of the ethernet link but how could this be causing a short on the board?

My board doesn't have the extra circuitry that the EVM board has (see image below), are these additional ICs necessary to maintain a proper PoE? The Magjack I am using has the transformer circuitry inside of it (Image below) but not the Zener protection circuit. If this circuitry is needed can it be placed after the transformer circuitry?  I provided my circuit (image below) to show how I incorporated the EVM board circuit.

MagicJack Circuitry (0857910020)

My circuit schematic

Alexander De La Rosa said:

The Magjack I am using has the transformer circuitry inside of it (Image below) but not the Zener protection circuit.

CCS/TM4C1294NCPDT: TM4C1294NCPDT Ethernet link sometimes doesn't get established. is a thread on a similar Ethernet failure on a TM4C129, with is a sister device to the MSP432E, which also involved POE.

The referenced thread suggests having the Zener protection circuit but with a too high a clamp voltage could cause a failure over time. Therefore, guess that not having the Zener protection circuit could also lead to a failure.