topic K60 AD sampling the biggest ,unknown reason in Kinetis Microcontrollers

K60 AD sampling the biggest ,unknown reason

qinzhang9887 — Wed, 31 Jul 2019 03:16:51 GMT

Input AD port signal, there is no abnormality. The voltage is about 15V after conversion, and the current is 0 under normal circumstances.

As analog signal processing, voltage and current, through partial voltage and operational amplifier, become a voltage signal of 0-2.5v and enter AD port

After several days of working, the result register of AD is read and becomes the maximum value, and the input signal of AD changes, but the value of the result register remains unchanged. See the figure below, the voltage changes to 25.4, the value remains unchanged, and the current changes to 840A

After 2-3 days of power failure, AD collection returned to normal

Re: K60 AD sampling the biggest ,unknown reason

FelipeGarcia — Thu, 01 Aug 2019 17:49:24 GMT

Hello,

Unfortunately, I cannot fully understand the problem you are facing. From what I can read, there is a high voltage in the ADC input.

However, there are a few things that you need to take care of, such as noise in the reference voltage or input signal, impedance in the input pin, etc.

I'd recommend you to take a look to the following document that can give you more hints to solve your issue.

https://cache.nxp.com/docs/en/application-note/AN5250.pdf

Hope it helps!

Best regards,

Felipe

Re: K60 AD sampling the biggest ,unknown reason

qinzhang9887 — Fri, 02 Aug 2019 04:32:17 GMT

Hello,

Thank you.Detailed description,Oscilloscope capture collection port waveform is no exception,The input voltage of about 2 v.Port input voltage is constant,Continues to run a few days later,Read the result register,The results for the max.

Power off will not back to normal. But,After 2-3 days of Power off, AD collection returned to normal .

Re: K60 AD sampling the biggest ,unknown reason

FelipeGarcia — Mon, 05 Aug 2019 21:07:41 GMT

Hello,

I am not sure if I am understanding correctly but here is what I understand.

The ADC was working fine but after a few days the ADC register reads the maximum value and no longer works even if you reset the MCU. After 2-3 days the ADC goes back to normal.

I would first check the input source of your ADC, it is likely that at some point you put a higher value to the ADC pins that can damage the functionality of the ADC.

I recommend you to check the chapter 6.6.1.1 and 6.6.1.2 of the datasheet to see the maximum values for voltage and current. Please make sure you are using ADC within the spec.

https://www.nxp.com/docs/en/data-sheet/K60P121M100SF2V2.pdf

I hope this helps.

Best regards,

Felipe

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