What is the maximum low output voltage of the INT pin?
I had an old datasheet (should have checked) from when the PCF2129 and PCF2129A had different datasheets, and here the datasheet for the PCF2129A version did not contain this parameter. I have now updated to the latest datasheet which covers both variants and includes this parameter.
It is 0.2 x Vdd as shown in the PCF2129 datasheet:
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