DRV8801 VBB is spec'ed for 8-36v volt operation, but nFAULT requires 12v. Given this spec, I choose this device to operate a pneumatic valve which requires 10 volts PWM.
The DRV8801 VBB range should be modified to reflect requirements for proper operation of nFAULT (VBB 13.8-36.0V), or make nFAULT work at 8volts.