Most pins on STM32 are "five volt tolerant" when switched to input mode and= allow 4 volts over supply voltage. I have no idea how they disconnect the = output transistors that could permit that, but I guess they do something cl= ever. Bob ________________________________________ From: piclist-bounces@mit.edu on behalf of James = Burkart=20 Sent: Monday, August 26, 2019 12:57 PM To: Microcontroller discussion list - Public. Subject: Re: [PIC] OD output on 18F47K40 controlling P-FET at 12.6V Thanks Bob! Yup, diodes to VDD on all the I/Os. I didn't even think to look at that. Oh well. -- Sincerely, James Burkart --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .