Too large PLLMUL (theoretical question)

[matic]

Posted on June 18, 2016 at 11:41

What would happen, if PLLMUL is set slightly too large? Let say, if maximum frequency of a MCU is 72 MHz, but PLLMUL is set such that the frequency would be 80 MHz?

Thanks

[Tesla DeLorean]

Posted on June 18, 2016 at 12:50

At some point you will encounter a critical path in the design, it will not catch fire, it will simply malfunction either in a subtle or spectacular fashion.

Think of it as a bus service with a rigid schedual, if you are not at the bus stop on time you will be left behind, and sometimes you can't run fast enough based on the conditions and length of the path you are running on. Think part of the circuit you are using, along with temperature, voltage and transistor characteristics.