ADCINA0 functionality

Hi Naveen,

This extract will make things clearer. As mentioned VREFHI is shared with ADCINA0 in some devices and if you plan to use External reference... ADCINA0 will be unavailable.

Regards,

Gautam

But i wanted to know what happens if i use it as variable source in external mode. Does it cause any damage or i just get wrong result.

Wrong results for sure! Also, if the input goes above absolute maximum rating as per datasheet then it might get damaged too.

Hi Naveen,

This pin is used as the external reference voltage in external reference mode.  That means you need to drive a stable DC voltage between about 2.0V and VDDA into this pin, and it sets the ADC range for all ADC inputs.  If you try to set the ADC in external reference mode, but drive a regular input into this pin, then the ADC will have no stable reference voltage and all the conversion results will be wrong (not just on A0).

Hi Devin,
Thanks for the explanation. But just confirm whether it is applicable to F28M36P63C2 . If applicable, then as said by you, do we have to supply stable reference to both ADCINA0 and VREFHI or I can leave ADCINA0 open and supply stable reference to only VREFHI.

OK, now i got it.

Naveen,

You can confirm this for yourself by looking at the Terminal Functions in the datasheet. You will be able to see very clearly that ADCINA0 and VREFHI have the same pin number when they are shared.

For example:

-Tommy