High Side Driver IC - Application Information
Automotive compatibility requires many repetitive impulse levels tests such as 5000 impulses at 50V.

This method of protection is essential to attenuate the over-voltage in 3stages.

1) an external MOV (  Dd ).
  2) a series R current limited zener.
  3) a direct clamp zener

Dgnd cathode protects reverse voltages to chassis Gnd below it.