I want to have a 5V trigger output signal that has rising and falling edges of up to 200ns max. into a load of 1-5 nF.
I thought about using MOSFET driver circuits (e.g. MC33152, many suppliers have similar). They are able to actively drive to GND and VCC (in my case 5V) with fast edges (range of 10-100ns) into some nF of load.
My problem: Because this 5V trigger will be an external pin, I need to make the driver output pins robust against, accidentially connecting external voltages (20-35V) to it and I have no idea how to do it.
I thought about using a schottky diode to block voltages from outside to go into the driver output. This however would also mean, that I could no longer drive the falling adge actively (because the diode will prevent that aswell). So I would need a pulldown resistor behind the diode, but this would not be enough to get steep falling edges.
How could I protect this trigger output against externally connecting 35V to the driver output pin without losing the possibility to drive the falling edge?