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Altera_Forum
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14 years ago

Cascading PLLs Cyclone II

Hey guys, I recently bought a MorphIC-II board that comes with a Cyclone II FPGA (EP2C5F256C8). I am trying to cascade two PLLs in my design. When I try to compile it I always get this err...
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Altera_Forum
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14 years ago

Looking at the block diagram in: http://www.altera.com/literature/hb/cyc2/cyc2_cii51007.pdf

The Cyclone II PLL can only be driven by the one of the four clock input pins that drive that PLL.

So theoretically you can cascade them, but it would require you driving the PLL output pin to the clock input pin of the next PLL.

Some families do have internal PLL cascading, but the Cyclone II is not one of them.

Pete