PLL analog voltage, cut through the filter and connected to VCCINT
What does analog PLL mean?
The so-called analog PLL means that the implementation of each module in the digital PLL is realized by analog devices, which is an analog circuit.
The advantage of analog phase-locked loop is that the circuit is simple and effective. When the low-pass filter is designed well, the output frequency is pure and stable, and the following performance is good. Under ideal circumstances, the output frequency is completely equal to the synchronous frequency, and the linearity requirements of the crystal oscillator voltage control characteristics are not high. The disadvantage is that once the reference frequency is lost, the output frequency immediately jumps back to the frequency of the crystal itself.