LT3775 have support ADISimpower Excel or LTpowerCAD simulation tool.for DC1290A-A &DC1290A-B? ,LT3775 peripheral parts much to calculate a very waste of time. if support ADISimpower or LTpowerCAD tool , this design very easy. thnaks
If you have not start the design yet, you can look in the LTC3867. It is a newer, current mode buck controller which is supported by LTpowerCAD.