Transil or Polyfuse for transient protection?

[blapcb]

What do you think is better for transient protection in a DC-DC supply which is to be used in automotive environment? Transil (SM6T from ST) or Polyswitch? (or maybe Bourns Resettable Fuse?).

Thanks

 

[FvM]

A polyswitch isn't providing any transient protection due to it's slow action. But it can be a useful supplement to a Transil diode. It can possibly help in handling a load dump situation. The power capability requirements for transil diodes in automotive are demanding, however.