ADC Count variation in MKE04

[prasannanaik]

Hi,

    In MKE04Z64VLH4 , I am sampling an ADC channel which has DC voltage at its input. But, ADC count which  I am getting has variations of 30-40 counts between Minimum to Maximum values. Logic which is used here is by triggering ADC at every 625 usec interrupt of PIT timer. 

  I have attached code which is used for sampling the ADC channel and there is no ripple in the power supply section.

Core clock is 40 MHz, Bus clock is 20 MHz and OSCER clock is 8 MHz.

Is it there any way by which this fluctuation can be reduced to 3-4 counts as DC voltage is stable?

Is it anything missing in code which causing this fluctuations in the ADC count?Please let me know.

Thanks and Regards

Prasanna

[kerryzhou]

Hi Prasanna Naik,

  Do you check your MKE04 VREFH, and VREFL?

 The reference voltage must be very stable, otherwise it will be influence the ADC convert data.

 If you connect the ADC pin to GND, the same as VREFL, whether it still has 30-40 variations ?

 Please test it on your side.

If you still have question about it, please kindly let me know.

Wish it helps you!

Have a great day,
Kerry

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