FAN5622 single-limb failures, what causes?

FAN5622 is a Fairchild part. I am seeing occasional chip failures where one of the two LED output limbs has failed open. The other limb is functional in all such cases. I’m looking at several hypotheses to explain the failures.

Would like to know if shorting a LED output to VIN (which is 5V) can be a potential cause of such failure. Since the output is a current sink (regulated current), in my view it should be capable of sinking that amount of current if LED output is shorted to VIN, indefinitely.

There is a TVS diode protecting the 5V, so I have ruled out excessive VIN as a probable cause.

Thanks for any clues.


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