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Original question:

TPS25750: Configuration of TPS25750D

TPS25750: About events that trigger PD negotiation

Taroimo
Intellectual 680 points
Part Number: TPS25750

Dear TI team

I have new question related to the content of the thread below.
e2e.ti.com/.../4711283

(a) There are three types of profile settings for TPS25750D: DRP (prefer power source/sink), sink only, and source only.
Is this correct? (There is no "do nothing" profile, right?)

(b) In the attached block diagram, we are considering setting the TPS25750D to DRP.

If the 5.0V on the same board as the TPS25750D is turned off and connected to an external USB device, the TPS25750D will be configured as a sink device.
After that, I believe that PD negotiation will not occur even if 5.0V on the same board as the TPS25750D is turned on.
(I understand that USB PD negotiation is only performed once when a USB device is connected.)
Is this perception correct?

(c) Please let me know if there is an event where PD negotiation is performed other than when the USB PD device is connected.

Best Regards,

Taroimo

  • 0
    TI__Guru 64841 points

    Hello,

    Taroimo said:
    (a) There are three types of profile settings for TPS25750D: DRP (prefer power source/sink), sink only, and source only.
    Is this correct? (There is no "do nothing" profile, right?)

    Yes.  This is correct.

    Taroimo said:
    If the 5.0V on the same board as the TPS25750D is turned off and connected to an external USB device, the TPS25750D will be configured as a sink device.
    After that, I believe that PD negotiation will not occur even if 5.0V on the same board as the TPS25750D is turned on.
    (I understand that USB PD negotiation is only performed once when a USB device is connected.)
    Is this perception correct?

    If the 5V onboard is not available, then this would be the dead battery case.  

    Do you want to initiate a role swap after the onboard 5V is connected?

    Taroimo said:
    (c) Please let me know if there is an event where PD negotiation is performed other than when the USB PD device is connected.

    I will need to double confirm but the request for role swap would initiate PD negotiation.

    Regards,
    Chris

  • 0 in reply to Chris Sterzik
    Intellectual 680 points

    Hi Chris,

    Thanks to you I have a better understanding.
    I want you to tell me just a little bit more.

    (b') "dead battery configuration" is what I understand to work when onboard 5V is not available and PD negotiation is not done.
    (That is, we don't refer to the "dead battery configuration" behavior in this case.)
    Is this perception correct?

    (c') I would like to know if there is a way to do a power role swap after the onboard 5V is connected.
    Also, is it safe to assume that roles will not be swapped unless a role swap request is made?
    (We want to avoid unintended role swaps.)

    Best Regards,
    Taroimo

  • 0 in reply to Taroimo
    Intellectual 680 points

    Hi Chris,

    I have an additional question regarding (b').

    (b'') Is it possible to enable "dead battery configuration" even if PD negotiation has already taken place?
    If this is possible, I think that by setting "dead battery configuration" = "safe mode", the "sink" path can be disabled even with the TPS25750D as the DRP setting.
    If possible please tell me how.

    Best Regards,
    Taroimo

  • +1 in reply to Taroimo
    TI__Guru 64841 points

    Hello,

    Taroimo said:
    (b') "dead battery configuration" is what I understand to work when onboard 5V is not available and PD negotiation is not done.
    (That is, we don't refer to the "dead battery configuration" behavior in this case.)
    Is this perception correct?

    There are three different dead battery configurations.  For both the AlwaysEnableSink and SafeMode the USB PD is disabled.  For the NegotiateHighVoltage the PD controller will enter the APP mode and negotiate the highest contract available up to 20V.  https://www.ti.com/lit/ds/symlink/tps25750.pdf#page=45

    Taroimo said:
    (b'') Is it possible to enable "dead battery configuration" even if PD negotiation has already taken place?
    If this is possible, I think that by setting "dead battery configuration" = "safe mode", the "sink" path can be disabled even with the TPS25750D as the DRP setting.

    No.  The dead battery configuration is applied at boot.  

    Taroimo said:
    (c') I would like to know if there is a way to do a power role swap after the onboard 5V is connected.
    Also, is it safe to assume that roles will not be swapped unless a role swap request is made?
    (We want to avoid unintended role swaps.)

    There are 4CC tasks.  https://www.ti.com/lit/ug/slvuc05a/slvuc05a.pdf#page=44

    You can also use a gpio event.

    Regards,
    Chris

  • 0 in reply to Chris Sterzik
    Intellectual 680 points

    Hi Chris,

     

    Thank you for teaching me many things.

    I have a better understanding.

     

    Best Regards,

    Taroimo