Tailoring the AD7173-8 ADC input range

I would like to take full advantage of the ADC's input range while using the internal buffers.

I have configured the ADC to run from a single +3.3V supply.

If the internal buffers are turned on, the absolute analog input range become 0 to 2.2V.

If I use a 1.1V external reference, the ADC range will match the absolute analog input range.

I don't think I want to use a resistor divider off of the ADR441 to create a 1.1V reference.

Should I buffer this signal with an amplifier for the reference?

- James

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  • Hi Jonathan,

    I don't think the ADR512 is a suitable replacement.

    It has 4x the output noise; 20x the temperature coefficient.

    I noticed that the ADR441 is used on the evaluation board and that there appears to be a resistor divider between the output of the part and the input of reference inputs. 

    I'm thinking about inserting an amplifier in a non-inverting configuration with a gain of 0.44 to create the 1.1V reference from the 2.5V reference output of the ADR441.  Is this a suitable approach to the problem and if so what amp would you reccommend?

    I'm thinking a low input bias current amp like the AD8615 would do the job.

    What are your thoughts?

    - James

Reply
  • Hi Jonathan,

    I don't think the ADR512 is a suitable replacement.

    It has 4x the output noise; 20x the temperature coefficient.

    I noticed that the ADR441 is used on the evaluation board and that there appears to be a resistor divider between the output of the part and the input of reference inputs. 

    I'm thinking about inserting an amplifier in a non-inverting configuration with a gain of 0.44 to create the 1.1V reference from the 2.5V reference output of the ADR441.  Is this a suitable approach to the problem and if so what amp would you reccommend?

    I'm thinking a low input bias current amp like the AD8615 would do the job.

    What are your thoughts?

    - James

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