Why does the Arria 10 External Memory Interfaces IP FPGA IO Settings for Data Bus Input Mode not support lower values than 60 ohms in the Quartus Prime software version 16.1.1 for DDR4 and QDRIV protocols?

Description

This problem has been fixed in Quartus® Prime software version 16.1.2. All supported values below 60 ohms can be selected for 1.2-V POD I/O standard targeting DDR4 and QDRIV protocols.

For the memory interface protocols which doesn’t use 1.2-V POD I/O standard (e.g. DDR3, RLDRAM3), input termination values below 50 ohms have been removed starting with Quartus Prime software version 16.1.1. More details can be found in this KDB answer.