PCF8523 Interrupt

I am trying to use the PCF8523 RTC to wake up my Arduino from deep sleep. I was planning on using the INT pin and configure an Alarm to do so.

From what I've read, the INT/SQW pin is an open-drain. I'm not entirely sure how that impacts the circuit design. If I connect the SQW pin to the Arduino in Alarm configuration, is there something else I need to add to the circuit to prevent the RTC battery feeding back into the IO pin (if that's even a problem)?

I'm concerned about the battery life of the RTC in this configuration.

A pullup resistor is required for such "open..." outputs, like with mode INPUT_PULLUP.

like with mode INPUT_PULLUP.

Got it. An external resistor will be required correct? I don't think I'll be able to use the mCU since it'll be asleep. Thank you!

The internal pullups are not affected by sleep.

Thanks!