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LPaul.11
Visitor II
August 19, 2020
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Crystal Selection for the STM32H753AI

  • August 19, 2020
  • 1 reply
  • 915 views

I am planning to connect a LSE 32kHz crystal and a 25MHz crystal to the HSE input, but I am having a hard time identifying whether the STM will drive my crystal selection within the limits of the 100uW drive level. I have read thru the app note, but it still isn't clear. The crystal I am using for the HSE is the ECS-250-8-33-JGN-TR. It has a 100uW drivel level maximum. Will this be compatible with the STM32H753?

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Best answer by TDK

I think it's something you're going to need to measure if you want a definitive answer, or contact the crystal supplier.

The app note gives steps for determining the drive strength and adjusting the resistor value as necessary. See "4.2 Detailed steps to select an STM32-compatible crystal". I imagine if it was something that could be conveyed in a single line in the datasheet, they would have done that instead.

https://www.st.com/resource/en/application_note/cd00221665-oscillator-design-guide-for-stm8afals-stm32-mcus-and-mpus-stmicroelectronics.pdf

You could also look at the max drive level of the recommended crystals to get an idea.

1 reply

TDK
TDKBest answer
August 19, 2020

I think it's something you're going to need to measure if you want a definitive answer, or contact the crystal supplier.

The app note gives steps for determining the drive strength and adjusting the resistor value as necessary. See "4.2 Detailed steps to select an STM32-compatible crystal". I imagine if it was something that could be conveyed in a single line in the datasheet, they would have done that instead.

https://www.st.com/resource/en/application_note/cd00221665-oscillator-design-guide-for-stm8afals-stm32-mcus-and-mpus-stmicroelectronics.pdf

You could also look at the max drive level of the recommended crystals to get an idea.

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