STM32F100 Temperatur Sensor with VDDA = 2.8V

[SPook]

​Hi,

I am usign the STM32F100RB with VDDA = 2.8V.

However when trying to use the internal temperature sensor I can calculate a slove of approx 2mV/K instead of approx 4.1K from the electrical caracteristics.

Is there anything different at 2.8V instead of 3.3?

Thank you

Stefan

[S.Ma]

If the supply voltage of ADC changes, its digital converted value will change too.

Maybe first cailbrate the ADC, then use Vref to get Vdda in mV, finally compensate the temperature value for it.

[SPook]

​Hi. Thanks for the very quick response.

The ADC itsself is quite fine.

The only thing I am really struggeling with is the temperature reference.

At approx 40°C (on chip) I get a ADC value of 2431 which corresponds to 1.662V

At approx 100°C (on chip) I get a ADC value of 2265 which corresponds to 1.548V

With these measurements the slope is 1.9mV/K instead of typical 4.1K from the book.

Is there anything I am missing in the calculation?

Stefan