MCU-PLUS-SDK-AM263X: ADC_CAL0,1 pins

Hey Saman,

I have reached out to our Analog design team for more information here. Please allow some time for team to assess and provide additional details once available.

Best Regards,

Zackary Fleenor

Hello Saman,

The CAL0 & CAL1 pins can be driven with any precision or ratio-metric voltage on the board and can be used to calibrate the error of the ADC reference or to validate the ADC from functional safety context. An example is given below

The built-in on-die reference has an accuracy of ~ +/- 2% and your ADC o/p can be written as Vcode=Vin/(Vref/2^12)=Vin*2^12/Vref --> Where Vin is the input voltage and Vref is the refernce which is 2% accurate making a 2% error in output computation. 

If you have a known voltage on the board then you can pass it to CAL0/1 and based on ADC o/p you can calculate Vref_measured=Vin*2^12/Vcode and eliminate the 2% error. 

Please note this equation is simplistic and ignore few details like input scaling, but as it is ratiometric, those approximations does not contribute any additional error. 

You can use CAL0 and CAL1 for a two point reference measurement to qualify the ADC or even have a dynamic known voltage to qualify the ADC  for the full input range in functional safety context.

Abhijit