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DP83867E: TD_P/M_x Diff Transmit and Receive signals I/O protection

Lidong Yu
Intellectual 1756 points
Part Number: DP83867E

Hello, I am checking if there is output short protection on the DP83867 Eth PHY TD_P/M_x Diff Transmit and Receive pins?  The external interface to these Tx/Rx pins include Magnetics (HM5149NL) isolation to the external connector, similar as shown in the System Diagram on sheet-1 of the DP83867 data sheet.   Per the data sheet the TDR feature does shorts detection (section 8.4.6.1 TDR), but want to be sure the PHY also automatically protects it's I/O (current limit) in case an external short is applied to these pins (with transformer in the middle)?   Thanks 

  • 0
    TI__Genius 16030 points

    Hello,

    There is no specific protection against short of pins. User needs to make sure that absolute maximum rating of each pin is not violated.

    --

    Regards,

    Vikram

  • 0 in reply to Vikram Sharma
    TI__Intellectual 1756 points

    Hello, I do not see the absolute maximum current rating for the transmit receive data interface in the DP83867 data sheet (pins TD_P_A-D & TD_M_A-D). Clarifying my question, the short of pins I am referring to is not directly on the DP83867 device but on the RJ45 connector pins which are isolated by the magnetics. See attached illustration of the scenario I am asking about. Could such shorts to external RJ45 connector cause damage to the DP83867 given it is isolated with magnetics coil, as recommended? thanks - Bela

  • 0 in reply to Lidong Yu
    TI__Genius 16030 points

    Bela,

    Yes, magnetics isolate the DC from RJ45 side to the PHY side. And shorting of RJ45 pins should not impact the PHY.

    Just for your reference, absolute max ratings are in the first subsection of "Specifications" : 

    --

    Regards,

    Vikram