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Original question:

TPS25750: Leakage current when powering from VIN3V3 or VBUS

TPS25750: VIN_3V3 required for sink-only application?

Kiran Kerai
Intellectual 380 points

Part Number: TPS25750

In a previous thread it was stated:

"When there is no power on VIN_3V3 and the TPS25750 is powered from VBUS, the current is being supplied by the charger at the other end of the Type-C cable which by the Type-C spec must be able to provide a minimum of 900mA. 

Also, this state should only be temporary."

Can this be confirmed that it should only be temporary? Why is this the case?

In a sink-only application, VBUS will always be available to power the TPS25750 and all internal circuitry will be powered through VBUS.

  • 0
    TI__Mastermind 33801 points

    The basis of that statement is because their is a valid current advertisement of 900mA in the type C standard and to be backwards compatible to the USB3.0 standard for the case that a typeA to typeC cable is used in the system.  This current must be met by the DFP that is supplying power in order to be standards compliant.  It is far more common for the DFP to advertise that it supports 1.5A or 3.0A, but the minimum possible is 900mA.  It the DFP/DRP and UDF/DRP are both pd compliant (typeC to typeC cable, then they can negotiate a contract with different current requirements per the standard.

  • 0 in reply to Chuck Branch
    Intellectual 380 points

    Ok so this is specific to an application where VBUS and VIN_3V3 are available? Here, the state where VBUS powers TPS25750 is temporary (during dead batter).

    In an application where there is no supply of VIN_3V3, VBUS will power TPS25750 permanently and there is no issue with this? Please confirm.

  • +1 in reply to Kiran Kerai
    TI__Mastermind 33801 points

    If the device is locally powered (DRP or DFP,) then VIN_3V3 and PP5V must be provided internally in order to the TPS25750 to be able to connect to the type C bus.

    If the device is powered from the BUS (UFP) then VIN_3V3 and PP5V are not required.   This is also true of the dead battery condition.  The TPS25750 will generate all necessary power supplies internally from VBUS.