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Hello Eric,
As Clemens showed, the input may be taken up to 38V without damage.
Though I would also place a resistor in series with the input to limit any transient currents (~10k should be fine).
Maximum input voltage is 3.3V - 2V = 1.3V. If you can bring the threshold down below 1.3V, then the output could still be correct.
See section 2 of the LM339 family appnote:
Application Design Guidelines for LM339, LM393, TL331 Family Comparators
Thank you very much.It means it will not demage the chip if the input signal did not exceed 38V although the supply voltage(e.g 3.3V) is less than the input signal voltage.