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Fallingelectron , 10-11-2025, 10:46 AM

Hi, i hope everyone is doing fine. i need help with the crystal selection for this MCU.
Keypoints to keep in mind are:
-Not using thIe RF capability of MCU
-its going to be a four layer PCB design
-I dont know what my PCBs stray Cap would be
also i don't understand how to choose a stack up for this PCB

QDrives , 10-13-2025, 10:19 PM

Crystal or (crystal) oscillator? Two different things.

Fallingelectron , 10-14-2025, 04:49 AM

@QDrives what is this?

Fallingelectron , 10-14-2025, 07:03 AM

this is what the datasheet says

QDrives , 10-14-2025, 01:00 PM

The datasheet you show is of a crystal.
PCB stray capacitance is usually in the range of 5pF.
As for the stack-up: one side components or both? Many traces or not high density?

Fallingelectron , 10-18-2025, 10:15 AM

one sided componets, i dont think it will have many components

QDrives , 10-18-2025, 04:33 PM

The best stack-up for that would be sig - Gnd - Sig - Gnd. You do need to pour copper on the signal layers to balance the copper, which should not be done without consideration.
Alternatively, Sig - Gnd - Gnd - Sig makes things easier. Here it is more important to add a Gnd via for signal vias.