Table 6.1 "Absolute Maximum Ratings" in the Datasheet lists 30V as "Absolute" MAX and MIN of the SW node.
I assume there is some minimum voltage limit for the device (i.e. -0.3V); can you confirm this value please?
Is there another parameter like "-3V for <10ns is also acceptable" or something? Some devices have this rating for SW as well...
Regards,
Darren