ADS7828: Ananlog input limitation.

balasubramani r

Expert 1170 points

Part Number: ADS7828

Hi There,

Working on this ADS7828 IC for my new development . Im using VCC as 3.3VDC so the internal Vref opted (ie 2.5V).

Is it ok give analog input upto VCC in all the analog channel or it should be restricted to Vref?

(like im going to give 3.3V in all the analog channel inspite of Vref 2.5V)

im planning to use it for NTC thermistor sensor measurement so the maximum of 3.3V expected in the analog channel.

Please advise the limitation

Reg,

Bala

over 7 years ago

0 Cynthia over 7 years ago

TI__Mastermind 25070 points

Hello,
The input range is determined by the reference voltage, thus if you want to measure an input signal at 3.3V but Vref is only at 2.5, you will not be able to measure anything above 2.5V
I would suggest using an external 3.3V voltage reference.
For this device, VCC does not determine the input range, but note that Vref should not be higher than VCC.

Regards
Cynthia

0 balasubramani r over 7 years ago in reply to Cynthia

Expert 1170 points

Hi Cynthia,

Thanks for the clarification.

This IC support external Vref voltage sounds good.

So the thumb rule is Vref should not exceed VCC, and input should be restricted w.r.t Vref .

Reg,

Bala

0 Cynthia over 7 years ago in reply to balasubramani r

TI__Mastermind 25070 points

Correct, I am glad this was helpful

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ADS7828: Ananlog input limitation.