Hello and thank you for your answers!
Isolation is not required for this application and safety will be assured by design. A flyback isolated converter could also work for the application, however, volume and price would be higher...
DeepOne, The topology you sent to me with the VIPER looks nice and thank you for the software. Actually it is quite similar to the one used with POWERINT LinkSwitch-TN, I have to analyze which option is better.
Switching frequency is 120 kHz.
Ernest