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TPD8S300: Does UFP design needs RPD_Gx resistors near TPD8S300 & TPS65986?

Pandiya Rajan
Prodigy 210 points
Part Number: TPD8S300
Other Parts Discussed in Thread: TPS65981EVM

Hi,

For a USB type-C UFP design, Where do we need to have RPD_Gx pins shorted to CCx pins for dead battery condition?

1. Is it near TPD8S300 side only?

2. Is it near TPS65986 side only? 

3. Is it near both TPD8S300 side & TPS65986 side?


In our design by default the RPD_Gx pins shorted to CCx pin only near TPD8S300. It power ON the board, but it does not enumerates the USB device . However if I connect the RPD_Gx pins to CCx pin near TPS65986, it is working. So my doubt here is, in dead battery condition the OVP FET inside TPD8S300 isolates these RD resistors in the CC/PD controller when no power. Then how the RD resistor near TPS65986 will be seen by USB source to detect dead battery condition.

Attached the Schematic for reference. Please help clarifying this.

Thanks

Pandiyarajan

USB_Type_C with TPD8S300 (3).pdf

  • 0
    TI__Genius 10370 points
    Hi Pandiya,

    Thank you for considering our parts for your design. In order for dead battery mode to work correctly, we recommend tying the RPD_Gx pins to the CCx pins on BOTH devices (#3 in your question). Section 8.3.4 in the TPD8s300 Datasheet explains this in more detail. I did notice that the RPD_Gx pin is not connected to the CCx pins on the TPD65986 device.

    I would also recommend to take a look at the schematic of the TPS65981EVM and use it as a reference when using the TPD8s300. This evm has a TPD8s300 connected to the PD controller, and this device is almost identical to the TPS65986. I hope this helps :-)
  • 0 in reply to Aramis P. Alvarez
    Prodigy 210 points

    Hi Aramis,

    I appreciate for your immediate reply... The section 8.3.4 explanation had made me to provide option in both ends however i thought the dead battery condition check will be done only on power up to supply VBUS. So that made me to write this query for clarification. So thanks for confirming it. I will test and verify this.

    Regards

    Pandiyarajan

     

  • 0 in reply to Pandiya Rajan
    TI__Genius 10370 points
    Hi Pandiya,

    It's my pleasure to help :-)