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hashtala
Associate III
May 9, 2020
Question

STM32F767 External Oscillator input Pins input capacitance

  • May 9, 2020
  • 5 replies
  • 1397 views

Hello

I want to include Crystal Oscillator in my project with STM32F767

According to CubeMX HSE pins are PH0 and PH1.

when it comes to determining values of loading capacitors datasheet suggests that input capacitance must be takes into consideration. However I cannot find anything about that in datasheet.

Could you please give me clues to where to find input capacitance of PH0 and PH1 ?

This topic has been closed for replies.

5 replies

waclawek.jan
Super User
May 9, 2020

It's not exact, but use the I/O pin capacitance value from I/O static characteristics table, usually 5pF.

JW

hashtala
hashtalaAuthor
Associate III
May 9, 2020

so 10pf or 15pf should be okay right ?

waclawek.jan
Super User
May 9, 2020

What's wrong with accepting 5pF?

JW

hashtala
hashtalaAuthor
Associate III
May 9, 2020

manufacturer of the oscillator I use required me that I use double the load capacitance. So since I am accepting your answer and taking copper trace's capacitance into account the most reasonable is 10pf (12 would be better but it is not available at local store)

Amel NASRI
ST Technical Moderator
May 18, 2020

Look to AN2867.

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