Forum Discussion

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

Quartus-II - Slow Slew Rate

I see there is a global "slow slew rate" option. Is it possible to turn it on for individual pins, using Tcl scripting? If so, how? If not, I guess I could turn it on globally; how much w...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
21 years ago

Thanks Scott.

Turning on "slow slew rate" didn't make much of a difference.

I explored a bit further and discovered the current limit control - Assignment Editor - Logic Options - I/O Features - Assignment Name "Current Strength" - Value "Minimum Current".

The "output pins" section indicates the current limit changed to 4mA (was 24mA).

Using this reduced signal products around 50-100 MHz by 3dB.

Slugging the output pin with 33pF further reduced those signal products by a further 3dB, and "eradicated" those above 100MHz. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/biggrin.gif