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Honored Contributor
Honored ContributorCyclone 4 ALTPLL wrong freq output
I used EP4CE55F23I7 in a custom board. The problem is that the output of the ALTPLL is wrong. Input clk freq is 50Mhz. ALTPLL output clk freq is around 100KHz although I configured it to an output...
Altera_ForumHonored Contributor
Honored ContributorThere might be few main reasons for PLL to not work properly:
1. Excessive jitter on reference clock (check PLL input jitter specification in datasheet) Personaly never had issues with jitter. 2. Power supply is not connected on VCCA VCCD_PLL GNDA pins. I think that there ar very litle chance that you have two boards with same soldering issue. I would rather go for schematic error. 3. Power supply noise Had this issue once. Check power suply noise requirements 4. Wrong PLL configuration.
