FS26 S32K3 ADC AMUX

[WeiC]

I use the ADC1 P1 channel of the S32K3 microcontroller to collect analog signals from the AMUX pin of FS26. AMUX switches to Low power bandgap for Main domain (1V), but the ADC result of the microcontroller is around 5000, which translates to a voltage of 1.5V. Why is the difference so significant？

[danielmartynek]

Hi @WeiC,

Have you measured the ADC input voltage on the pin?

What is the FREF voltage?

Can you share the ADC configuration like sample time, frequently, resolution, ...?

Thank you,

Daniel

[WeiC]

input volt is about 1.007V，ADC clock is from FIRC.

[danielmartynek · Accepted solution]

Hi @WeiC,

I'm sorry for the delay.

What is the VREFH - VREFL voltage?

The resolution is 14b, that is 0x3FFF = 16383

If VREFH - VREFL = 3.3V

LSB = 3.3 / 16383 = 0.20143mV

LSB * 5000 = 1.007V

So I would say, you use 3.3V reference but count with 5V reference.

Regards,

Daniel