Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

3.3V LVCMOS termination absent in Cyclone V??

Hello,

I looked at table 5-29: selectable i/o standards for rs oct without calibration

and table 5-30: selectable i/o standards for rs oct with calibration from cyclone v device handbook, and It seems there is no internal termination of any kind for 3.3V LVCMOS standard, while there is for 3.0V, 1.8V LVCMOS.

Why? Is there sthg I did not get? I’m a bit surprised…

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    you are right. I guess 3.3V with on-chip termination will require more current so Altera decides not to support it. Most of the time 3.0V or 2.5V will be good enough for interfacing 3.3V signal with on chip clamp diode on. I would consider to use lower voltage if OCT is really needed.