17.0V to 15.0V isolated and non-isolated power supply

Hi all,

From 17.0V DC supply I need to generate 15.0V at 500mA isolated power supply and 15.0V at 500mA non-isolated power supply both. I tried with WEBENCH Designer, but wasn't convinced with designs. Please suggest a TI/National  part number with schematics if possible. Please refer the power supply tree below for clear reference.

Thanks and regards

-Anand