Hi all, I am building the PIC18F4550 USB module and decided to use a 20MHz crystal oscillator. The PIC datasheet specifies to use a parallel-cut crystal but it does not specify the load capacitance and there is no mention of PPM for how much the USB clock can drift away from 48MHz before it starts failing.
Looking at Digikey I have filtered the products down this far: link but I am not sure what the difference between frequency tolerance and stability are as well as what ESR and load capacitance to go with.
Also, from what I understand you need to take stray PCB trace capacitance into account as well. So, how do you end up choosing what capacitors to place on either side of the crystal?
Thank you,
JP
Looking at Digikey I have filtered the products down this far: link but I am not sure what the difference between frequency tolerance and stability are as well as what ESR and load capacitance to go with.
Also, from what I understand you need to take stray PCB trace capacitance into account as well. So, how do you end up choosing what capacitors to place on either side of the crystal?
Thank you,
JP