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Altera_Forum
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14 years ago

switchover between 2 input clocks in pll (cyclon3)

i tried to insert 2 clocks into one pll and use the manual switch over ..the input clocks were 19.44 and 38.88 and the output clock was 172.8. the pll wasn't able to support this combination. what...
Altera_Forum's avatar
Altera_Forum
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14 years ago

I do not know the building bricks of an Altera PLL.

Consider that the output clock is calculated on the primary input clock and not on the back-up clock. You may need also a PLL reconfiguration to keep the same output frequency having two different input frequencies.