topic Re: ADC Tue and resolution in S32K

ADC Tue and resolution

luca_toso — Tue, 24 Aug 2021 07:31:57 GMT

Hi all,

For S32K14x MCUs, is there any difference for the TUE when resolution <12bit?

I'm interested in the 10 bit resolution scenario; I was studying the "Understanding ADC specifications" post by apanecatl and I saw that (in this example) there is a difference between 12 bit and <12 bit.

The DS for the S32K1xx family (rev.13,01/2020) provides only the typ and max tue for 12 bit scenario.

Any hind would be gladly appreciated.

Thanks and K.R.

Luca.

Re: ADC Tue and resolution

luca_toso — Tue, 24 Aug 2021 08:52:27 GMT

Additional question: when performing the ADC calibration procedure the TUE is reduced to 0 or generally speaking the TUE is the "unadjusted" error NOT related to the ADC peripheral calibration, but to other compensations?

Re: ADC Tue and resolution

danielmartynek — Tue, 24 Aug 2021 09:52:46 GMT

Hi Luca,

In the DS rev.13, above Table 41. 12-bit ADC characteristics, there is this note:

In other words, the specification is guaranteed only for calibrated modules.

Unofficial specification for your reference:

TUE 10bit resolution: typ. +-2, max. +-3 (LSB)

Please note that only the official specification in the DS is guaranteed.

Thank you,

BR, Daniel

Re: ADC Tue and resolution

luca_toso — Tue, 24 Aug 2021 09:58:47 GMT

Hi Daniel,

thanks for your quick and excellent reply!

What about the second part of the question and the TUE- does the calibration performed using SC3[CAL] reduce the TUE or the "total un-calibrated error" is not related to this ADC calibration?

K.R.

Luca

Re: ADC Tue and resolution

danielmartynek — Tue, 24 Aug 2021 10:17:52 GMT

There is no specification for uncalibrated modules. The TUE specification in the datasheet is only valid for a calibrated ADC. So we state that running self-calibration is mandatory. The exception would be when you do not require highly accurate conversions. The ADC of S32K14x is not calibrated in factory. The default register values copied from IFR are just ideal values, and correspond to calibration values for a "nominal device", but it is not the optimal calibration at all.

Regards,

Daniel