LM5150-Q1: Please help confirm the circuit for LM5150-Q1

Hi expert, 

Please help check if the application is Ok for LM5150-Q1. 

In the datasheet, the feature is:  Wide VIN input range from 1.5 V to 42 V when VOUT ≥ 5 V. 

My design concept is as bellow:

In the diagram, once the 12V input is lost, the voltage on Capacitor 330uF will be over 5.0V for a short time, and then the LM5150 will work, boost the backup battery-1.8Vmin to 12V. 

So, it is OK for this application?

Thanks a lot! 

Andy