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DP83561-SP: Ethernet PHY ESD Protection

James Yee
Prodigy 25 points

Part Number: DP83561-SP

Tool/software:

We are using the QML P/N: 5962F2021601VXC   (Texas Instruments DP83561-SP) Ethernet PHY in a spaceflight application, and looking for support on how to protect the device against ESD.  We currently have two TVS diodes Microsemi MS1N8155US connected in a Bidirectional configuration on each Ethernet signal pair.  These TVS diodes have a low capacitance of 4pF per device, however, they cause issues with the Ethernet signal. 

 

Do you have suggestions on how to protect the Ethernet PHY device against ESD ?  Is the built in protection of the Ethernet PHY device enough as-is ?  If the protection diodes are removed, the Ethernet functions properly.    

  • 0
    TI__Expert 7315 points

    Hi James, 

    The MDI pins are rated to tolerate up to +/-8kV without any additional ESD protection, as per the IEC 61000-4-2 standards. This should be good enough for most applications. Is additional ESD protection required in your application?

    Best,

    Vivaan

  • 0
    Prodigy 25 points

    Hi Vivaan,

    Thank you for your response.  Additional ESD protection is required, as we are required to perform qualification testing to MIL-STD-461 CS118 , upto +/-15kV.   Are there any recommended space-grade protection devices we could use?

    Thank you,

    James

  • 0 in reply to James Yee
    TI__Expert 7315 points

    Hi James,

    I wanted to clarify what kind of performance you are trying to test for exactly. Is the purpose of this test to see whether the PHY is damaged at 15kV or whether it is functional?

    Best,

    Vivaan

  • 0 in reply to Vivaan Jaiswal
    Prodigy 25 points

    Hi Vivaan,

    Purpose of the test is to see whether the PHY is damaged.  However, we determined that since we have the MDI pins routed out to an external connector, CS118 specifies that the 8kV contact discharge test method shall be used on the connector pins.   The 15 kV air discharge would not required, and the PHY should pass as-is with the 8kV contact discharge test.

    Thanks for all your help,

    James

  • 0 in reply to James Yee
    TI__Expert 7315 points

    Hi James, 

    Glad to know that the PHY should be able to pass the test. If you have any other questions, you can always reply back here, or create another thread. 

    Best,

    Vivaan