I am designing a board for a 12V automotive environment, with a variety of input voltage transients including load dump and permanent 24V over-voltage. I am using a TVS at the input to clamp to around 60V followed by a TI LM5060, a power supply supervisor, which in case of an over-voltage above 18V (or overcurrent) will cut off the power to my circuit using an external 60V MOSFET. The LM5060 datasheet specifies a 9.6 microsecond delay from the onset of a over-voltage condition to the MOSFET gate turning off. On the other side of the LM5060 I have my bulk capacitor and number of linear regulators and other ICs which at their input can tolerate up to around 30V (or 45V depending on what parts I choose).
So my question is, during that 9.6µs it takes for LM5060 to kick in, how can I ensure that nothing on its down-side gets fried? Is a sufficiently large bulk capacitor (220uF?) enough to absorb that transient? Or would I be better off using a small zener? How would I choose a value for this zener/capacitor?
If anyone knows of a better/cheaper alternative to LM5060, please let me know. I only need it to provide over-voltage protection up to around 60V.