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Original question:

TPS65987D: Voltage on VBUS line

TPS65987D: Starting PD Contract Directly at 20V (no 5V)

hermawan mulyono
Prodigy 130 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TIDA-050014, TIDA-050012

Hi,

We are using TPS65987D in our design and would like to connect 20V to a sink. A simplified diagram of our application is shown below.

It looks like from the following thread (scroll down till the end), it may be possible to do so.

e2e.ti.com/.../730824

However, the thread did not really mention how to set the source output to a voltage other than 5V by default. My question is:
How should I program the source and sink so that they automatically start the PD contract from 20V without having to start from 5V?

I have the .pjt files of TIDA-050012 and TIDA-050014 from the following links. Who knows modifying these files might be easier.

e2e.ti.com/.../749097

e2e.ti.com/.../740216

Regards,

Hermawan Mulyono

  • 0
    TI__Mastermind 36756 points

    Hi Hermawan,

    Unfortunately, it is required to start at 5V on VBUS per the USB Type-C PD specification. The TPS65987D is PD Compliant and cannot be modified to support this use case. To have 20V on VBUS, it is required to go through the PD Negotiation process. 

    If this answers your question, PLEASE select This resolved my issue

    Thank you,
    Eric

  • 0 in reply to Eric Beljaars
    Prodigy 130 points

    Hi Eric,

    Thank you for responding. I would like to confirm that it is not possible to use some trick such as setting the negotiation at 5V, but physically we are delivering 20V. It looks like from the datasheet there is an over-voltage protection (OVP) on the PP_HV pins. Moreover, from the Application Customization Tool, there is no way to set the PP_5V OVP to exceed 20V. Is this correct?

    Edit: I am just wondering if a 5V line is necessary on the source side because my current design does not have it.

  • 0 in reply to hermawan mulyono
    TI__Mastermind 36756 points
    Hi Hermawan,

    A 5V line is necessary on the source side. The TPS65987D would not work without it as it would not allow it to be PD compliant.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 130 points

    Hi Eric,

    Thank you very much for replying. I will add a 5V line on the source side in my design.

    Regards,

    Hermawan Mulyono