For the LPC5516JBD64 package the FB pin is not indicated correctly as shown in the Product Datasheet.
Datasheet shows the FB for the DCDC converter is on pin 29, in MCUXpresso Pin view the label for pin 29 is VSS_DCDC29.
I just got reply, development team will fix it.
Hello Adrian Lavin,
Thanks for your sharing, I think this is a bug in config tool, while I will submit a ticket to SDK team about this issue,
will tell you after I get reply.