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TUSB7340: Questions about I2C interface and D+ to Vcc leakage

Ronnie Hughes
Expert 3090 points
Part Number: TUSB7340

Can I2C be used to detect attach/detach events – i.e. link status? E.g. Table 162?

 

Can I2C be used to “dynamically” enable/disable a port?

Meaning the PHY is forced to not detect any USB device versus removing the controller from the OS (live) which would crash the host server.

               These are security features we are losing as USB host leaves the chipset.

 

Concerning Non-USB compliant devices (e.g. bias on D+ w/o VBUS being supplied to the device) – does this provide a leakage path through this IC to a VCC rail? 

e.g., this happens on southbridge USB Host controllers and creates issues.

  • 0
    TI__Guru*** 130835 points

    let me check with design if can do it. There is no I2C address in datasheet.

  • 0 in reply to Brian Zhou
    TI__Guru*** 130835 points

    it may not actively configured during operation by I2c,, the intent is for ports to be enabled / disabled at reset and then left that way.

     

  • 0 in reply to Brian Zhou
    TI__Expert 3090 points

    What about the leakage question:

    Concerning Non-USB compliant devices (e.g. bias on D+ w/o VBUS being supplied to the device) – does this provide a leakage path through this IC to a VCC rail? 

  • 0 in reply to Ronnie Hughes
    TI__Guru*** 130835 points

    you mean TUSB7340 power supply is off too?

  • 0 in reply to Brian Zhou
    TI__Expert 3090 points

    Yes, the TUSB7340 is powered off.  The customer wants to know if a bias voltage on D+ will leak thru the TUSB7340 onto any of its power rails.  If you have an EVM and can run some tests, check each of these conditions:

                   VBUS unpowered

                   D+ biased to +5V

                   TUSB7340 VDD33             3.3V I/O Power Rail unpowered                  what is voltage on VDD33?

                   TUSB7340 VDDA_3P3      3.3V Analog Power Rail unpowered           what is voltage on VDDA_3P3?

                   TUSB7340 VDD11             1.1V Core Power Rail unpowered               what is voltage on VDD11?

  • 0 in reply to Ronnie Hughes
    TI__Guru*** 130835 points

    yes, it will have leakage when power off but 5v on DP/DM.

    but we don't have EVM in the lab right now and this device is NRND