Hi VIGNESH,
The factory trimmed value of ICS_C3 and ICS_C4 vary from one MCU to another, although the frequency of IRC are default equal to 37.5kHz.
Even you trim the different chip to the same frequency, but the internal ICS_C3,ICS_C4 may have different data, the data is not fixed to different chip.
Manufacturing process yealds to frequency deviation, that is why all MCU devices are factory programmed with a trim value in a reserved memory location. This value is uploaded to the ICS_C3 register and ICS_C4[SCFTRIM] during any reset initialization. For finer precision, trim the internal oscillator in the application and set ICS_C4[SCFTRIM] accordingly.
About the ICS_C3 and ICS_C4, you can read below field descriptions.



Best Regards,
Robin