Power Supply redundant?

Hi everyone, 

I'm designing a PCB that includes UPD720201. I'm trying to follow the schematics from ET-D720201-0014(ISG-NC1-200052).pdf but I don't understand what happens with the Power Supply. The design is using one Boost converter to converter from 3.3V to 5V and other Buck to convert from 12V to 5V. What is the target of this?