I would like to control a +12 V line with a P-type MOSFET using the MC9S12XEP100 MCU. I wonder how high voltages it is possible to have on pins configured to operate in wired-or (open drain) mode? My idea is to have the MOSFET gate pulled to +12 V with a pull-up resistor while the wired-or pin is floating and pulled down to GND when I want to turn on the MOSFET. The +12 V line is further regulated down to a very smooth +5 V voltage after the MOSFET, so I have to use a high side switch to avoid voltage losses on this +5 V regulated bus.
I failed to find this information in the MC9S12XEP100 data sheet.