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September 26, 2023
Question

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

  • September 26, 2023
  • 2 replies
  • 1586 views

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)

 

This topic has been closed for replies.

2 replies

TDK
September 26, 2023

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
September 27, 2023

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.