Looking at the following document: Intel® Cyclone® 10 LP Device Datasheet
In table 3 on Page 7 VI is listed as 3.6V max recommended operating condition regardless of VCCIO
In Table 14 on page 15 max ViH is listed as VCCIO + 0.3V
There is also mention in Table 3 of AN 447: Interfacing Intel FPGA Devices with 3.3/3.0/2.5 V LVTTL/LVCMOS I/O Systems regarding use of the PCI clamp diode, but this may or may not apply to the 10LP (which does seem to have the Diode option).
Could you help clarify this for us? Thank you,
