PIC Microcontrollers......accuracy of internal reference?

[treez]

Hello,

I will be using one of the PIC microcontrollers in our Emergency light PCB. The PIC must monitor the battery voltage during charging (four series 1V2 NiCd cells)...so the ADC needs to be accurate......but this will depend on the accuracy of the internal reference inside the PIC.

So how accurate are the PIC range's internal voltage references?

 

[Tahmid]

Which PIC are you using? Not all PICs have a separate internal voltage reference for ADC. For most, it's VDD and VSS. So, it'll depend on the stability of VDD.

 

[treez]

thanks, i dont yet know the pic exactly, as it is big circuit for emergency light and we must investigate further

 

[Gimlix]

Why don't you use an external voltage reference? For instance:

https://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en019717

I'ts cheap, small SOT-23, and does the job quite well! Just use the output to feed the Vref+ of the internal ADC.

 

[learner71]

Internal Reference is not accurate, it will vary from microcontroller to microcontroller,even if you have chosen the same microcontroller number.
Better is go through external Reference.