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TPS65982: PD and data role switching issue.

Derek francavilla
Prodigy 20 points

Part Number: TPS65982
Other Parts Discussed in Thread: TPS65988

Hi. we are designing a dock station for the tablet which has USB 3.1 Gen2 100W PD USB C port.
I need help on choosing a proper PD controller and have some questions, because i dont have enough knowledge on the USB C.
Let me explain our system configuration.
We need two USB C ports, one is connected to tablet, another is for charger or device( such as USB flash memory, or HUB).
Charging option: two options - one from external DC power source, another is from industrial USB C 100W charger.  Tablet will be charged when either of charging source is plugged.
USB Hub IC -  TUSB2036VFR ( USB 2.0 3port - it can be changed).  USB HUB IC should work all the time even when the tablet is in charging status.
Question1: I think our device needs two USB C PD controllers, one for tablet and another for external( charging/DFP) USB C. And these PDs should be DRP and DRD, am i right?Question2: TPS65982 is standalone DRD and DRP without MCU controlling? Can we use this chip for our device? If not would you please recommend a proper PD chip?Question3: VERY IMPORTANT. When tablet is in charging status, tablet is also DRD, so can we get USB2.0 output( DFP) from the tablet? We need HUB IC( USB2.0) working all the time whether the charger is plugged or not.
Question4: Important. Charger side USB C PD( right side PD in the picture) will negotiate with the 100W charger. Does it automatically sends the information that the tablet is 100W PD, so charger can provide 20V/5A to the device?Qustion5: Can the left side USB PD change its function to SOURCE automatically, if 20V is applied to the VBUS, so it can charge the tablet?
I am really looking forward to your kind help.
Best regards.
Derek.

  • 0
    TI__Mastermind 37430 points

    Hi,

    Thank you for reaching out. You can go to this website (https://www.ti.com/solution/docking-station) for the TI docking station reference design.

    For question 1 and 2, TPS65982 is not recommended for new design, and since you have 2 type-c ports in your system, I would recommend you using TPS65988 since it is a dual port USB type-c and PD controller. The power role and the data role of the two ports on TPS65988 can be configured individually.in the GUI.

    For question 3, do you mean the type-c port on the dock becomes UFP? If so, TPS65988 have the ability to process the data swap request from far end to become a UFP.

    For question 4 and 5, I believe this is possible but I need to double check with my team to see how can this be configured in the GUI.

    Regards.

  • 0 in reply to Tommy Lin
    Prodigy 20 points

    Hi. Tommy. Thank you very much for your reply.
    I will take a look the reference designs and get back to you if i have more questions.
    Please let me know if you hear about question 4 and 5 from your team.
    I look forward to hearing from  you.
    Best regards.
    Derek.

  • 0 in reply to Derek francavilla
    Prodigy 20 points

    Hi. Tommy. I investigated on the TPS65988, it looks very good. 

    I draw power diagram for charging and discharging. 

                       

    Power source is two. One is 100W USB C charger , another is an external PSU over DC barrel port. So USB C charger and external PSU will never used at the same time. Only one will be used at a time. 

    For charging, Tablet is sink and DFP, so portA at the TPS65988 side, is SOURCE and UFP. USB charger is SOURCE, UFP. port B at TPS65988 side is SINK, DFP. 
    For discharging, power roles are swapped, but USB2.0 data role is not changed. 
    Am I right? 
    Question1: the above block diagram is correct? 
    Question2: PortA and PortB changes their charging/discharging role automatically according to the 20V/5A     existence( from PSU or USB charger)? 
    Question3: When using the external PSU( USB charger is not applied), only 20V is applied to the external FET. So how does change portA to SOURCE role automatically?
    Best regards. 
    Derek. 

  • 0 in reply to Derek francavilla
    TI__Mastermind 37430 points

    Hi,

    The block diagram looks correct to me.

    For question 4 and 5 on the initial post and question 2 and 3 here, you can check out section 3.36 0x5C GPIO Configuration in the TPS65987DDH and TPS65988DH Host Interface Technical Reference Manual (www.ti.com/.../slvubh2b.pdf to see if there are events that fits your need. I think the plug event and barrel jack event is what you are looking for.

    To change the source/sink PDO and port roles based on events, you need to send 4CC commands through I2C to the PD controller. The 4CC commands can also be found in the Host Interface Technical Reference Manual.

    Regards