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Original question:

TUSB320: Changing mode configuration(DFP/UFP/DRP) during power-on & cable connected

TUSB320: Change power mode without removing cable

Kuenrg
Intellectual 480 points
Part Number: TUSB320

Following up on https://e2e.ti.com/support/interface/f/138/t/817624?tisearch=e2e-sitesearch&keymatch=TUSB320

I am designing an application where the device (wall charger) initially receives power from the the phone/tablet/etc. Then, after waking up fully, it starts to deliver power to the device from the battery or AC power. This should happen WITHOUT plugging in the cable a second time.

If I put the device in DRP mode how can I get it to start as an UFP and then change to DFP? Or can I get it this by toggling EN_N? Or should I just toggle Vdd? (I have a separate MCU available for changing registry settings, etc.)  Please also comment if I need to toggle or disconnect some of the lines from the USB C cable temporarily in order to simulate a reattachment of the cable. (I hope I do NOT have to do this but understand if maybe toggling Vbus or CC lines will help.)

Any design recommendations are most appreciated!

  • 0
    TI__Guru 64326 points

    Hi,

    As you may have guessed when TUSB320 is in DRP mode a cable reattachment is necessary for renegotiation into a different mode (UFP or DFP). If the only requirement is to receive default current from attached device then holding Vdd low will but TUSB320 into Dead battery mode. This is present you wall charger as a UFP only device. Then when ready you could raise Vdd and disable Rd termination through I2C. This should cause the attached device to see a disconnect event. Could you explain why you need to charge from attached device initially?

  • 0 in reply to Malik Barton57
    Intellectual 480 points

    Thanks Malik,

      It's a pretty simple application - want to make a truly zero quiescent current wall wart.

    So the initial connection uses power from the attached device to powers up MCU and turn on some SSRs which turn on power from the wall.  Then I need to simulate/trigger a cable reconnection so that the wall wart is now DFP and charges the device as normal. (When device battery is really dead then a simple button press on the wall wart engages the AC power)

     So the revised question is: how can I simulate a disconnect event so that the USB configuration is renegotiated. Through experiments I've found that simply disconnecting the VBUS line and reconnecting it is not sufficient. (Though maybe there are multiple power lines in a USB C cable?)

  • 0 in reply to Kuenrg
    TI__Guru 64326 points

    Hi,

    For Type-C a disconnect is not  only seen via Vbus as it would be in Type-A/B USB applications. Disconnection is also seen through the CC lines, by removing or disabling Rd/Rp termination. This can be done through I2C by toggling the TUSB320 register DISABLE_TERM. 

  • 0 in reply to Malik Barton57
    Intellectual 480 points

    Hi Malik,

      That seems to have worked!
      I'm now working at making sure I'm charging in high power mode but I'll open another thread if I need help with that.

    Thanks,
    Kurt