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TPS65987D: BC1.2 setting in 0x29 register

Antony Lin
Genius 13480 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987,

Hi,

Should we expect TPS65987 would short DP and DM pin while BC1.2 is configured as DCP in 0x29 register?  Also this setting at host side(laptop) should not be workable with a USB2,0 disk?

PLease check below for the DP/DM measurement with them connected from type-c connector to TPS65987 while a USB2.0 disk is connected (through a type-c to type-A dongle).  These two waveform show the behavior of DP/DM while 0x29 BC1.2 setting is changed between DCP and CDP.  Customer said their laptop with such test can still detect the USB20 disk correctly.  Is it correct behavior?  Why?

DCP switched to CDP

CDP switched to DCP

Thanks!

Antony

  • 0
    TI__Mastermind 36756 points
    Hi Antony,

    It looks like this is the correct behavior. Per the BC1.2 spec, the D+/D- lines will be released after the detection or advertisement is complete. The USB2.0 lines would then be free to enumerate the USB disk.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    TI__Genius 13480 points

    Hi Eric,

    If customer has a special request to still being able provide 5V to a USB2 device, but don't want the USB2 data to be functional.  What can be done from our side?  Can we achieve this by setting USB2Connection bit to '0' or anything else?

    Thanks!

    Antony

  • 0 in reply to Antony Lin
    TI__Mastermind 36756 points
    Hi Antony,

    This could not be acheived with the TPS65987D. The TPS65987D only sniffs the USB data lines. Reporting USB2connection in PD would not apply to a USB2 device.
    If they want to disable the data connection for USB2, they would need to do so with another IC on their board. Maybe through the USB Hub.

    Thank you,
    Eric