>>and some higher AC voltage.  I typically connect a 10K between the INT
>>pin and 12VAC to detect AC line zero crossings (see the Shoebox dimmer at
>>http://www.dovesystems.com).  Microchip has an application note where
>>they do this to detect zero cross by running a resistor directly to the
>>120 VAC line.


Man I hope no humans can come into contact with that!