ADC Tue and resolution

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ADC Tue and resolution

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luca_toso
Contributor II

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. 

luca_toso_0-1629790151395.png

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

luca_toso_1-1629790258389.png

Any hind would be gladly appreciated. 

Thanks and K.R.

 

Luca. 

 

 

  

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danielmartynek
NXP TechSupport
NXP TechSupport

Hi Luca,

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

danielmartynek_0-1629798226396.png

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

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danielmartynek
NXP TechSupport
NXP TechSupport

Hi Luca,

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

danielmartynek_0-1629798226396.png

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

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luca_toso
Contributor II

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

 

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danielmartynek
NXP TechSupport
NXP TechSupport

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

 

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luca_toso
Contributor II

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? 

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