TPS65987D: Power up without VIN_3V3

Part Number:TPS65987D

Hi,

In this project, TPS65987DDJ is used as DEVICE (with no other external power and battery) where the power is coming from USB Type C VBUS connected. Based on the datasheet section 8.3.2, it mentioned that, when VIN_3V3 is unavailable and VBUS/VBUS2, TPS65987D can be powered up.

Questions:

1) In this case, do we still need to supply VIN_3V3?

2) If question 1 is yes, is there a timing requirement when VIN_3V3 must be available after VBUS is plug in?

Thanks.

Gim Song