powerSTEP01 package (VFQFPN 11x14x1.0 mm) thermal resistance

[RSopp.1]

For documentation purposes i need to estimate the worst case temperature for the powerSTEP01 that occurs in our application. I already calculated the worst case power dissipation so i am able to determine the temperature with information about the "junction-to-ambient"-thermal resistance. Unfortunately i can not find information about that in the datasheet. Has anyone an idea where i can find them?