I think this powerdown is not really related to the adt chip/driver.
I think it's more likely some PMU issue and the PMU forces the machine
down. How's the PMU involved into temperatures? Does it get
the temperature values from the adt chip?
It is connected to the overtemp alarm interrupt pin of
the temperature sensors at least.
Does this shutdown only happen if you boot Linux while
you were running Linux before, too?
Segher