ID:15914 Input port <text> of PLL "<name>" must be driven by a pin.

CAUSE: When the OPERATION_MODE parameter of the specified PLL is set to EXTERNAL_FEEDBACK, the fbin input of the specified PLL must be driven by a pin, that is the fbin input must be driven by an IO Output Buffer which is driven by an IO PAD.

ACTION: Make sure that the fbin input is driven by a pin.