ADC reference Voltage

[Arrowspace]

Hello is their any relation between reference , input and resolution of ADC

 

[paulfjujo]

Hello,

YES !
Resolution = Vref/ N bits ADC
more datas ! ..in the specsheet of ADC

 

[Arrowspace]

and maximum input voltage

 

[milan.rajik]

Vref+ should not exceed 5V. Also there should be a difference of 2.5V between Vref- and Vref+ in PIC.

 

[Arrowspace]

Means if I connect +2.5V at +Vref and -2.5V at -Vref and I read negative voltage using PIC

 

[milan.rajik]

You can't input negative voltaged to ADC pins. If you set Vref- to 1V and Vref+ to 3.5V and measure.

 

[hobbyckts]

Even your output voltage depends on the VREF.

 

[KlausST]

Hi,

Have you read the adc specification and theory of operation?
There you find all the information.

You didn't say what ADC you use.

I'm just working on an ADC with Vref of 1.25, but with input voltage range of +/- 1.0V (LTC2170).

Klaus

 

[Arrowspace]

I am using AD7328 at reference 3VDC for reading input voltage with range +/- 10VDC, my problem is that I am getting full reading from 0 to 10Vdc on my LCD display but resolution is not good . when I change 1 volt my display also get change by 1 volt ,but not getting intermediate value

 

[KlausST]

Hi,

your problem most probably is a software problem.

***

You need to supply your ADC with at least +/10V to be able to input +/- 10V signal.

Klaus