ReubenMijares
Newbie level 6
In most ICs I encounter, PLLs are present. But I don't know actually what's the use of it. Some registers are associated with it which you need to program. May I know what's the use of this PLL and why are the registers need to be configured?
I know how PLL works. It takes 2 input frequencies, one is from a crystal oscillator which is stable, while the other one is from a VCO. The phase difference is compared to create a signal with a stable phase/frequency.. What I don't understand are the following:
1.) The crystal oscillator is already stable. Why not just use that signal for the clock? No need to compare 2 signals, right?
2.) What are its used for digital circuits? Is this to create a stable clock?
3.) Can you explain how programming the registers can alter the behavior of the PLL?
Regards,
Reuben
I know how PLL works. It takes 2 input frequencies, one is from a crystal oscillator which is stable, while the other one is from a VCO. The phase difference is compared to create a signal with a stable phase/frequency.. What I don't understand are the following:
1.) The crystal oscillator is already stable. Why not just use that signal for the clock? No need to compare 2 signals, right?
2.) What are its used for digital circuits? Is this to create a stable clock?
3.) Can you explain how programming the registers can alter the behavior of the PLL?
Regards,
Reuben