DRV8307 DRV8308 OCP of mosfet

Dear sir,

l have questions about OCP function  drv8307/drv8308.

1.Does Drv8307/8 measure the voltage across  VM and pin-U to determine whether the high side MOSFET-U is over current or not?

If it is in this way, it means that the pin VM of drv8307/8 and the motor power VM must be tired together?

2. Does Drv8307/8 use pin-ISEN and pin-U to determine whether the low side MOSFET-U is over current or not?

3. Can l add a RC filter on pin-ISEN?

4.can l add a OPAMP to amplify the Rsense voltage and then connect to pin-ISEN?

Jiang Shiou,Taiwan