Re: Circuit protection 24V
That pulse is generally known as Load Dump pulse. In automotive standards (SAEJ1211), the pulse specifications (Peak Voltage, Time etc) are given for 12V and 24V systems.
Generally, a TVS(Transient Voltage Suppressor) diode is used at the input of the regulator. Also, some additional circuit is required to operate TVS diode in safe mode is required. The circuit design is depend on the minimum input voltage required for the regulator and maximum circuit current.
---- Nandu