Jerry,
The TSU6721 does go high impedance from VBUS pin to OUT pin when the MIC path is selected. However there is a body diode on the FET that will conduct from OUT pin to VBUS if there is a voltage > than a diode voltage drop.
Thank you,
Adam
Vlad,
The load switch will conduct any time there is a voltage present on VBUS >3.6 V.
For example if, let us say the TSU6721 device was on a cell phone and it was OTG mode where the phone is now the host. The phones power management IC (PMIC) would provide the USB standard 5V on the OUT pin of the TSU6721. In the diagram above you can see there is body diode that will conduct in this situation and ~5V - 0.7 V (diode) 4.3 V would appear on VBUS turning on the load switch providing a low impedance path from OUT to VBUS of the TSU6721.
Here is an appnote that explains a little bit more detail of the TSU6721 Accessory and Charger Detection Flow for some extra color beyond the datasheet.
Thank you,
Adam
