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Altera_Forum
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9 years ago

Cyclone IV PLL min input frequency

Hi, What is minimum input clock for Cyclone IV E PLL? Data sheet states that minimum Fin=5MHz, but PLL locks even to 500KHz input clock freqency. Can someone explain this to me? Thanks
Altera_Forum's avatar
Altera_Forum
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9 years ago

I second Alex's recomendation. You will find that as temperature changes and/or electrical noise is added or even changes your PLL won't lock reliably any more. We had one in our lab that was sometimes locking to a WiFi router that was nearby rather than the way out of spec input signal. "It works in the lab, why doesn't it work at the customer's site"?