Forum Discussion

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

cyclone 3 restricted fmax

Hi, at some point during my work I needed to use a higher frequency clock in Cyclone 3 (EP3C16) speedgrade -8 and thought of a 400 MHz clock. In the Cyclone 3 Handbook volume 2 table 1-19 it i...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

--- Quote Start ---

P.P.S.: Or do you have a M9K-block connected to this clock? That has a fmax of 238MHz with -8 speedgrade.

--- Quote End ---

Yes, Quartus knows about the frequency, i constrained the PLL input and the 400 is inclk x 10. Duty cycle is 50%.

There is a small altera fifo generated here (built around an M9K), i guess you're right. I should generate it in logic (size only 4x16). Hope it works!