Hello Toshio-san,
It looks as though you are applying a load dump pulse that corresponds to Automotive application. Presently, we are working on a schematic for a protection network that would precede circuitry such as LM22676 in question. Will you be interested in a schematic of this approach? If so, send me an email on a*n*s*t*o*n[at]ti[dot]com (please remove'*' mark)
Thanks,
Anston