MSP430F6736A: Displaying wrong AC voltage if it exceeds 275 VAC

Hi Rahul,

Is the observed value normal below 275VAC? You could check that whether the signal exceed the SD ADC input rang when the voltage exceed 275.

Hi Allen,

Yes value observed below 275VAC. When the VAC is 270, it shows around 235 and when it's 240, it shows ~200 VAC. But when I soft reset MCU then it shows correct voltage. It seems there is some EMDC library issue when voltage exceed 275 VAC threshold and gets resolved after soft reset (resolved only if VAC is less than 275 VAC). 

Hi Rahul,

Have checked that is the input signal exceed the input range(when 275 input)?  The input voltage from the resistance need to follow the spec.

Hi Allen,

But it should show the accurate voltage once the device returns to the ADC input range. I keep getting wrong VAC unless I soft reset the MCU.

Hi Rahul,

If you have exceed the ADC input range, the ADC value is overflow and it may influence the algorithm in library. That is the reason why you down to the range the the VAC value is not the correct value but when you reset, everything is ok.