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16bit ADC Questions

Question asked by Sean Havanas on Nov 28, 2016
Latest reply on Dec 1, 2016 by Sean Havanas

We are using a Kinetis K64FN1MOVLQ12

 

The on board ADC is used along with a Difference amplifier, to scale 15V and/or 24V signals to 3V.  The ADC is calibrated with a  liner ‘ mX+b’ gain and offset equation.

 

The question;

  1. What is the Vin linearity to measure specification?
  2. We are seeing a ‘sawtooth’ offset error, repeating approximately every 450mV with a very steep offset change.  See attached.

 

Are there setting which can be controlled to achieve better performance?

  • Frequent use of the ‘Auto-zero’ command?
    • Presently Auto-zero is only implemented on power initialization.
  • Faster or slower clock speeds,
    • presently using 6.125MHz.
  • A more readily available ADC Kinetis version?
    • Possible medical device with increase ADC capability?
    • Drop in replacement?

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