• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 32 subscribers
  • Views 95 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TUSB8020B: SS_DN1/SS_DN2 pins

Imre Sunyi
Prodigy 110 points
Part Number: TUSB8020B

Hi Ti

The datasheet for the pins SS_DN1 and SS_DN2 how are they supposed to interpret?

I intend to put the device into SMBus mode and have both downstream ports support superspeed. Is the SS_DN2 pin an indicator (output) indicating to a microcontroller the status of the port or a control (input) where a microcontroller can set the port type? Datasheet says it is an input but for the SS_DN1 which is the same indicator but for the other port it says it is an input/output. Should not the SS_DN1/2 pins have the same direction?

I interpret that I need to have low level on SS_DN2 on reset to set device in SMBus mode and after reset set SS_DN2 to high level to have superspeed support on downstream port 2.
Same for SS_DN1 to have it low on reset to set device PWRCTL active high and after reset set SS_DN1 to to high level to have superspeed support on downstream port 1.

Can you please clarify?

Br
Imre

  • 0
    TI__Guru 60865 points

    Hi Imre,

    At power on reset, the pin configuration function on these pins (SMBUSZ and PWRCTL_POL) are sampled to set SMBUS or PWRCTL_POL functions of the TUSB8020B.  SMBUSz/SS_DN2 should be marked as a I/O pin in the datasheet.  

    SS_DN1 and SS_DN2 are output status functions that are enabled after SMBUS mode and PWRCTL_POL modes are set.  SS_DN1 and SS_DN2 report if the associated ports are connected at superspeed only, they do not impact the hub function.  Some customers use these pins for debug or to drive LEDs, they are not required to be used.

    Regards,

    JMMN