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TPS65987DDK: Behavior when TPS65987DDK is unpowered

Ryuuichi machida
Guru 12715 points
Part Number: TPS65987DDK

Tool/software:

Hello,

I would like to confirm following behavior on TPS65987DDK.
Note : Device is set as "DFP" on configuration file.

* When user do not supply power to TPS65987DDK (This means user do NOT supply voltage to "LDO_1V8", "LDO_3V3".).
Under this condition, when certain "DFP"(Source) equipment is connected, what behavior can we observe on TPS65987DDK ?

What my concern is when certain "DFP"(Source) equipment apply certain "Rp" to TPS65987DDK in above condition, TPS65987DDK behave as "Sink" and do NOT show "Not connected"(Not "vOpen" state) state.
Is there possibility that TPS65987DDK behave such condition ?  

Best Regards,

  • 0
    TI__Expert 8190 points

    TPS65987DDK has a built in Rd resistor which is always active when there is no VIN3V3 supply. 

  • 0 in reply to Ghouse Mohiuddin23
    Guru 12715 points

    Hi Ghouse-san,

    Thank you for your reply.
    I have one additional question.

    *
    >TPS65987DDK has a built in Rd resistor which is always active when there is no VIN3V3 supply. 
    In this case, what behavior can we show on PowerPath line ?
    In general, I believe that internal power path can be controled after user input 3.3V to "VIN_3V3".
    (As an exception, case of TPS65987DDK enter "APP" mode (or dead battery mode). In this case, I understand internal supply change form VIN_3V3 to VBUS.)

    Our configuration is "DFP"(Source) only mode and use only "PP_HV2" (PP_HV1 is connected to GND).
    Our concern is when certain "DFP"(Source) equipment is connected under unpowered, internal powerpath is "closed".
    If this cause, DCDC converter and other circuit will cause damage due to reverse voltage.

    I would like to confirm whether even if we can see "Rd" under unpowered, internal powerpath is "opened" or not.

    Best Regards,
     

  • 0 in reply to Ryuuichi machida
    TI__Mastermind 30492 points

    Hi Ryuuichi, 

    1- See Dead Battery Operation section in the datasheet on Rd presence on CC pin. 

    The power path behavior is dictated by the dead battery configuration set. The power path remains disabled until VIN3V3 is present in BP_NoResponse configuration (see below). 

    Best Regards, 

    Aya Khedr 

  • 0 in reply to Aya Khedr
    Guru 12715 points

    Hi,

    Thank you for your reply.
    How about "unpowered" status about PowerPath ?
    When external equipment with DFP(Source) is connected under "unpowered", internal PowerPath is also disabled ?

    Best Regards,

  • 0 in reply to Ryuuichi machida
    TI__Mastermind 30492 points

    Hi Ryuuichi, 

    When the dead battery configuration is set to "BP_NoResponse", no power path will be enabled. Once VIN3V3 is present in the system, and the dead-battery flag is cleared, the device will then proceed with normal operation and become the power Source. 

    Best Regards, 

    Aya Khedr

  • 0 in reply to Aya Khedr
    Guru 12715 points

    Hi,

    >When the dead battery configuration is set to "BP_NoResponse", no power path will be enabled. Once VIN3V3 is present in the system, and the dead-battery flag is cleared, the device will then proceed with normal operation and become the power Source. 
    => Is my understanding correct that even if 3.3V (VIN_3V3) is not supplied to the TPS65987DDK (even if the device has not booted up), when certain source device is connected, the device recognizes the pin setting of ADCIN configuration and checks the “dead battery” mode setting ?

    Best Regards,


  • 0 in reply to Ryuuichi machida
    TI__Mastermind 30492 points

    Hi Ryuuichi, 

    Your understanding is correct. The device checks the ADCINx pin setting upon boot. 

    Best Regards, 

    Aya Khedr 

  • 0 in reply to Aya Khedr
    Guru 12715 points

    Hi

    Thank you for your reply.
    I have one additional question.

    * I understood when user connect certain "DFP"(source) equipment to board which is implented TPS65987DDK under unpowered status, board which is implemented TPS65987DDK behave as "UFP"(sink).

    However, I would like to confirm whether above "UFP"(sink) device will communicatie "DFP"(source) device via CC line after that ?
    What I would like to confirm is whether there is possiblity that "DFP"(source) device will supply over 5V.
    (if negotiation will happen via CC line, VBUS will change from 5V to certain voltage (depending source requirement))

    Best Regards,

  • +1 in reply to Ryuuichi machida
    TI__Mastermind 30492 points

    Hi Ryuuichi, 

    During dead-battery, the PD is powered from VBUS at 5V only as this would be a Type-C implicit contract, no PD contract.

    Once the configuration is loaded, since the PD is configured as a source-only, the PD will not be able to Request PDOs from the Source. 

    Therefore, once VIN3V3 is available, the MCU will need to clear the dead battery flag so that the PD can begin advertising its Sourcing capabilities. 

    Best Regards, 

    Aya Khedr