S32K14x meaning of FIRCERR bit in SCG_FIRCCSR register

[dawidbabula]

Hello, 

I got two questions regarding to the FIRC: 

1) what is the precision of FIRC in case of FIRC regulator is disabled 

2) what is the meaning of FIRC trimming error  ( FIRCERR 26th bit in SCG_FIRCCSR register ), when can it happen ? what influence for FIRC precision it has ? 

Best Regards,

Dawid

[jorge_a_vazquez]

Hi Dawid Babula

The FIRCREGOFF bit is used to control an internal regulator used by the FIRC internal circuit. In order to guarantee the operation frequency of the FIRC at voltage levels higher than 3V and inside the specs, this bit has to be 0. Unfortunately, we cannot guarantee a frequency operation when the internal regulator is disabled.

The FIRC trimming error bit is applicable when you trim the operation clock of the FIRC to other than the default (48 MHz) and there is detected an error on the change. It is not applicable if you cannot change the freq.

Hope this helps

Best regards

[SONGTAOSI]

Hi,

I have same doubt，Can you give further answers？

1.how to  generate FIRC clock error ?

2.Whether or not S32K1xx  not applicable as FIRC can only have 48MHz?

Best Regards,

[dawidbabula]

The FIRCREGOFF bit is used to control an internal regulator used by the FIRC internal circuit. In order to guarantee the operation frequency of the FIRC at voltage levels higher than 3V and inside the specs, this bit has to be 0. Unfortunately, we cannot guarantee a frequency operation when the internal regulator is disabled.

This is clear to me, but still don't answer to my question about precision of FIRC, when regulator is turned off. Do you have some hard data ? Is it 4% or more in whole temperature/voltage range ? Another question is, why would anybody want to turn this regulator off ? 

The FIRC trimming error bit is applicable when you trim the operation clock of the FIRC to other than the default (48 MHz) and there is detected an error on the change. It is not applicable if you cannot change the freq.

That means that for S32K144x it's not applicable as FIRC can only have 48MHz. Can you please tell me then, to which microcontroller this flag is applicable ? 

Best regards,

Dawid

[jorge_a_vazquez]

Hi Dawid Babula

No, we don't have this data available as this is not a common use, and it varies widely. You could turn off this regulator for power saving purposes.

Regards

Jorge Alcala

[dawidbabula]

No, we don't have this data available as this is not a common use, and it varies widely. You could turn off this regulator for power saving purposes.

Ok, thank you for the answer. What about my second question, do you know the answer maybe ?