Sorry for simple question regarding ADCs

[arunb]

Hi,

I am using an MCP3208 ADC to measure signals.

Do I have to give a separate reference voltage to the ADC or can I use the same +5V supply that is required for the ADC ??

thanks
arunb

[libor]

With the reference you determine the maximum measurement range. Yes you can use the same 5V if you are measuring up to the 5V range. (if you have a lower level of input range you can increase resolution by setting the reference to a lower voltage, this reference voltage will be the max scale value on the ADC reading)

For improved precision, there a caveat regarding digital noise on the supply rail, so you can decouple the Vref using an RC filter (e.g. a series resistor of 100-500 Ohm, with a capacitor to the ground of 1uF - 100nF will do I think)

[rnielsen]

It is recommended to have your grounds separated. Have digital parts and analog parts on different ground traces. This will help minimize noise on the analog A/D parts. Always use caps (~.1uf) to help with this as well.

Ronald

[Humberto]