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Kinetis K22 Measure Temperature Using ADC

Question asked by Elkana Bronstein on Nov 17, 2015
Latest reply on Dec 6, 2015 by Elkana Bronstein

I want to use the "temperature sensor" feature of the ADC.

 

I use Kinetis K22F Sub-Family processor, for which the temperature slope is (Typ.) 1.62 mV/C and the ADC resolution is 16bit.

I read carefully AN3031 and the post about the slope calculations here and SW implementation wasn't a problem.

 

My MCU Vcc is powered by 3.0V +-3% via LDO.

 

 

1. For a reason I don't understand, any minor change in Vcc result with a major temperature error:

    Shouldn't the 3% error be negligible if ADC proportional to 1/Vcc :

    Delta_ADC = a/100 - a/103 = a*3/10000

 

2. Is there a way to use another reference (i.e. VREF) for the temperature sensor?

 

Thanks

 

 

 

 

 

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