STM32WL5MOC LSE 32kHz accuracy

[50_ohm]

Hi, 

In the STM32WL5MOC datasheet I can find the 32MHz TXCO HSE accurancy, but not the LSE 32kHz RTC clock accuracy. Could someone look into this and provide the min/max values similar to TXCO characteristics in Table 10?

Best Regards,

Dave

[Peter BENSCH · Accepted solution]

Welcome @50_ohm, to the community!

I am very sorry that this specification is not mentioned in the data sheet. However, I would like to point out that the frequency accuracy of the 32MHz HSE is an essential prerequisite for proper functioning in some frequency bands.

The built-in LSE crystal has a frequency tolerance of ±20ppm at 25°C and a parabolic coefficient of -0.04ppm/°C². If there are any deviations, you can use the smooth calibration function included in the built-in STM32WL55JC, together with the temperature sensor if necessary. I have also explained the smooth calibration in a more understandable way in this thread. There is also a Knowledge Base article describing the smooth calibration for the STM32U575 which uses a similar RTC.

Hope this answers your question?

Regards
/Peter