Further to my previous question, Using a PIC to perform switch on and timed shutdowns in automotive environment

I've been pointed at zener diodes and voltage dividers, but I'm now confused by the PICs builtin weak pull-up resistors (and if I check the datasheet, values are TBD... I assume something like 10k?)

So the PIC input pin protection circuit I think I have understood is this:![PIC input pin protection circuit][1]

But using weak pullups, I think I could do this:

![enter image description here][2]

But all this does is swap a resistor to a diode.

• Is the voltage divider circuit correct?
• Is the circuit that uses the weak pullups correct? (i think not)
• Why would I use pullups over normal voltage divider? [1]: https://i.sstatic.net/3ZcjK.png [2]: https://i.sstatic.net/f0Ntg.png