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TPS23880: The PE connection issue of TPS23880

Chen Jiao
Intellectual 810 points
Part Number: TPS23880

Hi team,

The ground for TPS23880 is connected to the Protective Earth (PE), and the noise from the PE results in failure detection of PD devices. Is this situation evaluated before?  Is there any solution to deal with this issue when the TPS23880 needs to connect to the PE?

Thank you.

best regards

Chen Jiao

  • 0
    TI__Genius 15685 points
    Hi Jiao,

    Why do you need to connect the TPS23880 ground directly to the earth ground? Can you show the detection waveform? Usually there are some caps between TPS23880 ground and earth ground. Thanks.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    TI__Intellectual 810 points

    Hi Penny,

    The diagram is shown in the attached picture. The equipment connects with external devices through HDMI, and the external device's ground is connected with the earth ground for safety, if the DCDC is used to boost 12V to 48V to supply PSE, then the ground for PSE will connect with the earth ground. Except replacing the DCDC to an isolated DCDC, is there any solutions to solve the issue?

    The detection waveform can't be got and the failure detection condition is very rare.

    Many thanks.

    Best regards

    Chen Jiao

  • 0 in reply to Chen Jiao
    TI__Genius 15685 points

    Hi Jiao,

    When you see the detection failure, does it happen only one time or the PSE keeps failing the detection? In semi-auto or auto mode, TPS23880 keeps doing detection if the detection is not valid. To solve the problem, an isolated DCDC would be good. Before changing to isolated DCDC, probably there are some other things you can try:

    1. Add some filter at PSE input
    2. Add some filter at the PSE port

    Thanks.

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    TI__Intellectual 810 points
    Hi Penny,

    Could you please tell me what is the filter? Is the filter should be a LC? Is there any schematic diagram or application notes to help me? Many thanks.

    Best Regards
    Chen Jiao
  • 0 in reply to Chen Jiao
    TI__Genius 15685 points
    Hi Jiao,

    For port filter, you can look at the schematic in this app note. www.ti.com/.../slua818.pdf. Thanks.

    Best regards,
    Penny
  • 0 in reply to Penny Xu
    TI__Intellectual 810 points
    Hi Penny,

    Thanks for the explanation. Could you please tell me if there is any testing scheme to evaluate the ground noise's interference on the handshake between PSE and PD ?
  • 0 in reply to Chen Jiao
    TI__Genius 15685 points

    Hi Jiao,

    You can just connect the PD to the PSE port and see if the PSE is able to successfully detect the PD. Thanks.

    Best regards,

    Penny