DRV11873: Question of FS Setting

Part Number:DRV11873

Hi

I have question of DRV11873.

1.
What is  the difference between high speed fan motor and low speed fan motor?

Fast Motor RPM is more than 10000.

Low speed fan motor is not more than 1800.

How do you choose between 1600 and 10000.

2.

Should  the FS pin  be pulled high?

Now,I am using the Smart_28S motor of  Nidec.

The required motor speed is 7200.

The FG frequency is 480 Hz.