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TPS65982: Using the TPS65982 in a DP alt mode

guy lemire
Intellectual 950 points
Part Number: TPS65982

Hello,

I am using the TPS65982 in a DP Alt mode source application. I am connecting my AUX channel to the AUX_P/AUX_N pins and I wanted to know if the appropriate pull-up/down resistors were incorporated in the TPS part or I need to supply these resistors externally.

Regards,

Guy

  • 0
    TI__Mastermind 36751 points
    Hi Guy,

    The TPS65982 has the appropriate pull-up/down resistors internal. No external resistor is required on the AUX_P/AUX_N channels.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Intellectual 950 points

    Hi Eric,

    thank you. I did find it in the manual. However, it looks like the values will support a DFP (source for DP) but not a sink for DP which requires a 1Mohm pullup/down. Can you confirm my understanding.

    Regards,

    Guy

  • 0 in reply to guy lemire
    TI__Mastermind 36751 points
    Hi Guy,

    The TPS65982 also has the correct pullup/down for DP sink. I was able to test it on our EVM and the DP expansion EVM to confirm functionality. We placed placeholders on the DP Expansion EVM for pullup/down resistors on the AUX_P/AUX_N lines but both are DNP. You can review the users guide for the DP Expansion EVM that includes schematics at the following link:
    www.ti.com/.../slvuar1.pdf

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Intellectual 950 points

    Hi Eric,

    we are designing a DP Source (DFP_D) and I have a follow on question. In order to set the internal pullup/down resistors to the appropriate values for Display Port in this mode of operation, I assume I write to the DP Configuration Register (0x51)

    bit 14 0b0 ---- USB Type C Receptacle

    bit 9:8 0b10 ---- DFP_D

    I am measuring the static DC voltage on the AUX lines (SBU1/2) and I do not see the correct values (I should see approx. 3.3V through a 100k pullup on AUX_CH_N and approx 0V through a 100k pulldown on AUX_CH_P. Is there some other registers that I need to touch to enable the pullup/down resistors.

    Regards,

    Guy