Hardened circuit protection against voltage spikes and surges tackled in this app note from Vicor. Link here (PDF)
Electrical systems in military vehicles are normally required to meet stringent transient requirements. Typical of these specifications is the MIL-STD-1275B. Although the specified levels of these surges and spikes are outside the capability of Vicors Maxi, Mini, Micro Series modules, it is quite possible, with simple circuitry, to make the 24V input (18 – 36V input range) DC-DC converter modules compliant to these specifications for the 28V vehicle voltage system. Other electro-magnetic compatibility requirements, such as MIL-STD-461E and/or DEF-STAN 59-41, apply to military vehicles, but these are outside the scope of this application note. In order to meet additional conducted emission requirements an input filter, preceding the transient protection circuit covered in this application note, will be required.