Forum Discussion

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

PLL cascading on Cyclone V - broken?

I'm trying to cascade 2 plls on the Cyclone V (5CEBA2F23C8). Both integer. I set the first to have a cascade_out and the 2nd to have adjpllin. Then I connect these. Even with an otherwise empty...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
9 years ago

I tried with some larger devices and found that it does not synthesize on the Cyclone V E A2 and A4 - but it does on the A5,A7,A9.

On the device datasheet the number of plls increase after the A4 (A2:4,A4:4,A5:6,A7:7,A9:8). So I guess pll cascading is not supported on the 4 pll Cyclone V E devices. Is this down to the lack of a 'pll strip'?

I wonder if this is a Quartus bug or just the devices do not support this. I can't find anything in the device manual or family overview.