ADC Conversion results not accurate

prasannanaik — Wed, 16 Oct 2019 11:40:00 GMT

Hi,

I am trying to sample 3 ADC channels (SE8, SE9, SE15) with sampling frequency 1.6KHz. I have connected a bypass capacitor of 0.1uF on each ADC pin. I am not able to achieve accurate ADC conversion results with DC voltage at ADC input pins. There’s a considerable difference between the expected conversion value and actual conversion result. Also the difference is more for higher DC input voltage on ADC pins.

I have attached the test results for reference.

Development Board used: FRDM K22F

ADC configuration:

Clock used: BUS clock (frequency 60MHz)
Clock Divider: Divided by 4

ADC Calibration: Auto calibrated

Long sampling: Disabled

Continuous conversion: Disabled

Please help in resolving the issue.

Thanks and Best Regards,

Prasanna

Re: ADC Conversion results not accurate

jingpan — Thu, 17 Oct 2019 07:46:58 GMT

Hi Prasanna,

Please refer to this link.How to make ADC counts "stable" in K20/K22 MCU ?

It has some good suggestion. Beside AN4373, AN5250 is also valuable. https://www.nxp.com/docs/en/application-note/AN5250.pdf

Regards,

Jing

topic ADC Conversion results not accurate in Kinetis Microcontrollers

ADC Conversion results not accurate

Re: ADC Conversion results not accurate