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This is a question regarding STM32 crystal and Load CAP(2)

13eta
Associate

13eta_2-1695716395458.png

Data for the parts used are shown in the photo above.

13eta_1-1695716316818.png

I made the calculation as above, but I am curious as to whether I obtained the CL value correctly.

 

result)

→ECS-.327-12.5-12R-C-TR (32.768kHz   CLoad 12.5pF, Cs 5pF)

CL1=CL2=(CLoad-Cs)*2=(12.5pF - 5pF)*2

CL1, CL2 →15pF (14~16pF)

 

→ECS-120-8-36-CKM-TR (12Mhz  CLoad 8pF, Cs 5pF)

CL1=CL2=(CLoad-Cs)*2=(8pF - 5pF)*2

CL1, CL2 →6pF(5~7pF)

 

2 REPLIES 2
TDK
Guru

Best to keep the discussion in a single thread. You can reply to your other post to add more details as needed:

https://community.st.com/t5/stm32-mcus-boards-and-hardware/this-is-a-question-regarding-stm32-crystal-and-load-cap-2/td-p/593673

If you feel a post has answered your question, please click "Accept as Solution".
EZHON.1
ST Employee

we need to consider the track capacitors from crystal to MCU. 

in this case the CL1 and CL2 value is less than your calculation.

anyway, the test accuracy is important when you get the board.