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RTOS/MSP432E401Y: Absolute Maximum Ratings of Ethernet Port

Austin Chen55
Prodigy 20 points
Part Number: MSP432E401Y

Tool/software: TI-RTOS

Hi TI,

The absolute maximum ratings of VIN_GPIO is -0.3V to 4V

Since the Ethernet line drive of MSP432E401Y is CML(current mode logic), the signal on MDI would exceed 4V.

Does the Ethernet port have its own absolute maximum ratings?

  • 0
    TI__Guru**** 244380 points
    Hello Austin

    The Ethernet lines for 100 Mbps copper is +1V,0V and -1V for signalling. The Inductive coupling (provided by the transformer) will allow only the dynamic signal to propagate and rebiased. This should not be a problem as we have tested with PoE with 24V DC superimposed and the device functions as expected.
  • 0 in reply to Amit Ashara
    Prodigy 20 points

    Hi Amit,

    The standard operation voltage of PoE is 48V. So  we've tested under this condition and several MSP432E are crashed. MSP432E would draw extra 60mA from Ethernet port.

    We can observe the abnormal signal while PoE turning on. I attached our waveform while PoE turning on. How about the absolute maximum ratings under this condition?

    CH1: VCC_MCU_3V3 (MSP432E VCC)

    CH2: EN0TXO_P

    CH3: EN0TXO_N

    CH4: VCC_POE_5V(PoE PD output)

  • 0 in reply to Austin Chen55
    TI__Guru**** 244380 points
    Hello Austin,

    The MSP432E4x should not be drawing the extra current from the line. If this is a PoE design, then you need a different front end to remove the 48V and current for the same compared to a non-powered line. The PoE standard allows for non-PoE devices to work without issues.

    When you mention a crash, is this a SW crash or there is a HW damage that causes the device to be non-operational. The ESD structure should prevent any fast transients from going to the PHY. Please advise.
  • 0 in reply to Austin Chen55
    TI__Guru**** 244380 points
    Hello Austin

    Is there any further update from your side or any additional questions?

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