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TPS65983B: Time for fast swap role

user4964096
Prodigy 30 points
Part Number: TPS65983B

Hi sir

I have  the question from TPS65983B about the total time of fast role swap between TPS65983B and cell phone mobile.

I am worried about this question,if facing high current/high voltage , we need the margin time of FRS to inform system prevent from damage.

Thanks

.

  • 0
    TI__Intellectual 990 points

    Hello User, 

    After the receipt of the FRS message, the host has less than 150us to assume the source role. 

    This post has more information about the FRS switching considerations: https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/10/25/switch-it-quick-with-ti-39-s-fast-role-swap 


    Jaime 

  • 0
    TI__Mastermind 36751 points
    Hello,

    FRS time is dependent on many variables. Mainly the amount of capacitance on the system power rail and the discharge rate of that capacitance.
    Could you give me some more details of your system and application?

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 30 points

    Dear  ,   Eric Beljaars

    Refer to              e2e.ti.com/.../switch-it-quick-with-ti-39-s-fast-role-swap

    For Figure 1 , Suppose USB PD Host  is mobile phone ;  I use TPS65983B for USB PD Hub.

     Normally ,The charger charge the mobile phone through USB PD Hub, and the charger supply voltage for the phone and all circuit of PD Hub.

     If suddenly remove the charger , the load switch maybe disconnect or turn off,  it results at one problem where from or how to supply the PD Hub voltage

    to sustain enough voltage for TPS65983B and other circuit ???

    So, for PD3.0 specification ,the time of fast swap role is important to decide the chip function off/on for PD Hub. 

    As I know, when the charger is removed, the PD hub will let CC pin pull low, so that the mobile phone can check the CC pin signal, and prepare to supply power to PD Hub.

    I want to know the how long is the mobile phone supply the voltage to PD hub after all signal communicated  between PD Hub and mobile phone ???   

    For hardware design for PD Hub, I usually use the larger capacitance to keep the voltage enough to supply TPS65983B and other circuits.

    Please help me .   thanks