DRV3901-Q1: Diagnostics during power loss

Tool/software:

Hello team,

I want to perform diagnostics during the power loss.

I have placed bulk capacitors across VREG pin to meet requirement of pyro trigger during power loss. 
Do I need to put bulk capacitor across PVDD pin also to perform diagnostics or VREG is sufficient as main supply is VDRV?

In the below link it is mentioned PVDD as main supply. I agree during normal conditions current comes across PVDD but wanted to understand is it same during power loss and diagnostics need to be performed.

 DRV3901-Q1: Current consumption 

Thank you,