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Original question:

TPS65988: Supply if not short

TPS65988: When is the internal switch turned on?

DDdoor
Expert 2435 points
Part Number: TPS65988


Hello

When 3.3V power can not be obtained from the external to the TPS65988,
I think that if the type C cable is connected, power will be supplied to the TPS65988 itself using VBUS. After that,
I think that TPS65988 negotiate with DFP side using cc pin. There is HV Gate Control between VBUS and PP_HV1 of TPS65988.
I want to know when this will turn on. Is that after the negotiation is complete?
Or is the current such as 0.5 A flowing before the negotiation is completed?

Best regards,
DDdoor

  • 0
    TI__Mastermind 36756 points

    Hi DDdoor,

    The internal power path of the TPS65988 will turn on based on the setting you have enabled. If you have it set to be a Source power path. It will turn on as soon as 5V needs to be a source on VBUS, immediately after a connection. If you have it set as a sink, it will turn on immediately after a connection as well. However, if you have it set as a sink with wait for SRDY command, then it will only turn on after you send the SRDY command over I2C.

    Thank you,
    Eric

  • 0 in reply to Eric Beljaars
    Expert 2435 points

    Hello Eric,

    Thank you for your reply.
    I have found an SRDY command in your answer, but where is this listed?
    I think that there is no statement about the command and the register map in the data sheet.

    ・datasheet

    www.ti.com/.../tps65988.pdf

    Best regards,
    DDdoor

  • 0 in reply to Eric Beljaars
    Expert 2435 points

    Hello Eric ,

    If a customer uses TPS65988 as a sink and sets to receive 5V 1.5A, if a legacy USB (0.5A) is connected as a source, it will not meet the sink's request.
    In that case, I believe that the switch remains OFF. Is it correct?

    Best regards,

    DDdoor

  • 0 in reply to DDdoor
    TI__Mastermind 36756 points

    Hi DDdoor,

    you can find more on the SRDY command from the Host Interface TRM document: http://www.ti.com/lit/ug/slvubh2b/slvubh2b.pdf

    If there is a 0.5A legacy USB connected to a TPS65988 set with a sink capability of 5V 1.5A, it will still close the switch unless the SRDY command is used.

    Thanks,
    Eric

  • 0 in reply to Eric Beljaars
    Expert 2435 points

    Hello Eric

    I have confirmed SRDY from 4.10.1 ‘SRDY’ – System ready to sink power item in the following link.
    The material is overlapped as shown in the attachment, making it a little difficult to see
    and I don't know what is written. Is there anything written correctly?

    Best regards,
    DDdoor

  • 0 in reply to DDdoor
    TI__Mastermind 36756 points

    Hi DDdoor,

    Thank you for pointing this out, I will work with the team to get it fixed. In the meantime, just the Output Data section looks effected. It should read the below:

    The ‘SRDY’ Task shall be considered rejected if:
    • PD Controller is not in a Sink role.
    • SwitchSelect == 000b through 011b and the specified switch is not configured for input.
    • The selected switch cannot be enabled for some reason (UVP/OVP or some other fault).

    The ‘SRDY’ Task shall be considered successful if:
    • PD Controller is

    Thank you,
    Eric