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This is a question regarding STM32 crystal and Load CAP.

13eta
Associate

 

13eta_1-1695714945111.png

First of all, I changed it to the corresponding part, but I would like to ask a question to confirm.

 

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Part selection was carried out as follows, according to the formula in the photo above.

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Even though I looked into the Gm value, I couldn't understand it well.

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*Can I set gmcrit to correspond to the 'higher driving capability' area of the LSE part of the STM32L072's data sheet? What is the difference between lower driving capability and higher driving capability?

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*There doesn't seem to be a separate performance-related area set for the HSE part, so I'm wondering if I just need to set gmcrit to not exceed that value. (For example, is there no difference between 0.1mA/V and 0.5mA/V?)

First, I set gmcrit = 2.2603uA/V for 32.768kHz and gmcrit = 0.576mA/V for 12Mhz to ensure that the gain margin of all related components exceeds 5. Is this okay?

*Also, the smaller the Load CAP and the lower the crystal frequency, the lower the power consumption. When comparing the extremely low 8Mhz crystal (CL1 CL2 value close to 5pF) with the extremely low 16Mhz crystal (CL1 CL2 value close to 25pF), How much difference will there be in power consumption?

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