TPS51397A: IC shorting and no longer working after drawing ~0.75-1A at 4.75V.

Hello,

I am using the TPS51397A Buck IC as a voltage step-down component.

My voltage input is 12V at 2A peak, down to an output of a 4.75V at 4.6A peak.

Currently, I have the IC mounted to a 2 layer pcb, where upon startup at 12V, the buck runs normally with a stable 4.75V output (with little current draw). As I increase the current draw, the source remains stable, up until I reach 1.71A of current draw on the load, and suddenly the IC shorts (the 12V net to the 4.75V net shorts together) and the component no longer works. Essentially, it is cooked instantly and damaged by a very sharp, but short current spike. I've replaced the chip several times on different PCBs (copies of the same design), with each meeting the same fate.

Clearly, these parameters are comfortably within the component specifications. Minimum capacitance is met comfortably, as well as inductance. Mode selection is based on reference design given (4.5V at 5A).

Any ideas as to why this IC is failing and unable to meet its specifications?

I have attached a scope screenshot, with the waveform in green showing how the output voltage drops sharply upon reaching 0.6~0.8A of current draw. Enable line is also in purple, and FB pin is in blue.