The nFAULT pin has an open-drain output and should be pulled up to a 5-V or 3.3-V supply. When a fault is detected, the nFAULT line is logic low.
For a 3.3-V pullup the nFAULT pin can be tied to the DVDD pin with a resistor (refer to the Application and Implementation section). For a 5-V pullup an external 5-V supply should be used. TI does not recommended connecting the nFAULT pin to the AVDD pin.