Hi H.Someno,
You can just leave the SYNC pin floating if it is not used.
Unfortunately, there is no LM5026 calculator available for LM5026. You can refer to datasheet section 8.2.2 for detailed design procedure with its corresponding application circuit as…
Yoshida-san
LM5025 and LM5026 can start up and operate when an external voltage between 8V to 15V is applied to VCC, as specified in section 6.3 Recommended Operating Conditions of both datasheets. PMP7895 is an example reference design with LM5026 where…