UCC28631 is exhibiting a latched fault mode of operation. No PWM operation with VDD swinging between 8V and 10V.
Presume this due to pin fault detection. Appears to be associated with the DRV output as the low side switch appears to be stuck ON (1.2 ohms to GND) after removal of power. After some period of time, output goes to high impedance.
How to resolve pin fault startup issue?
Separate issue:
When it does startup, it doesn't appear to regulate. Demag time meets Tsample setup timing, but appears as though being ignored or not responding appropriately. Shuts down/Auto-restart due to Over Voltage protection.