Differential Amplifier for 32-bit ADC

I am working on an VirtualBench Projects that uses the AD7177-2 32-bit ADC.

Does anyone know any good amplifiers that wil work well With the 32-bit ADC?

I am looking at these parts.

External gain: AD8253

5.00v ref: ADR4550

2.50v ref: ADR4525

Diff-amp: AD8475

Amp: ADA4805

Know any other good diff and singel ended amps?

  • 0
    •  Analog Employees 
    on Mar 6, 2018 12:14 AM

    Hi Kim,

    May I know what projects/applications are you working on and why do you need a 32-bit ADC?

    Where is your input voltage coming from? Is it coming from the sensors? What is the signal characteristics of the sensors (sensitivity, voltage range, frequency, etc)? This information are important so that we could select suitable amplifier parts for your target applications.

    Also, we have evaluation board available for AD7177-2 that you could purchase. Please see the link here.

    The user guide contains its schematic which you can use as reference for your external circuitry like power products, reference voltage, filtering, etc.

    Best regards,

    Emman

  • The 32-bit ADC is going to be used for DC voltage measurement.

    Input voltage to diff.amp:
    +/-5mVdc (AD8253, AD8421)
    +/-50mVdc (AD8253, AD8421)
    +/-500mVdc (AD8253, AD8421)
    +/-5Vdc (AD8253, AD8421)
    +/-10Vd (AD8253)

    I have been looking at the AD8421 and AD8253 diff.amp with external gain.
    After the external diff.amp with gain I was thinking about using the AD8475/AD8253 to send the signal to the AD7177-2.
    Do you think this is a good solution for the measurement selection?

  • 0
    •  Analog Employees 
    on Mar 6, 2018 10:57 PM

    Hi Kim,

    When you say DC voltage measurement, does your input coming from the power supply, precision voltage source, or any specific sensors? I am just concerned that this 32-bit ADC has an overkill specs for your application.

    If you need a programmable gain amplifier then I agree that AD825X family is suitable for your application. Sensing +/10V may overload the ADC input and therefore you need to put an attenuator and a simple resistor divider can do the job but you can also use the AD8475 as shown on this article which is recommended for wide range DAQ instrument measurement range.

    Other amplifier recommended from its evaluation board are ADA4528 and ADA4522.

    Best regards,

    Emman

  • The DC voltage measurements are for general use like batteries. power supply, analog sensors and sow on.
    The 32-bit is not overkill, not that expensive chip anyway.

    I am going to look at the ADA452X to, tnx for the help

  • Hi Emman,

    I wanna use the Ad7177 evaluation board to acquire the EEG signal. I have checked the datasheet and found the input buf amplifier ADA4528 on page24. But I am not sure this is enough to amplifier the EEG signal. Do I need to add extra instrumentation amplifier?

    And the tutorial of the mother board SDP-B is too short. If I want to write some program on the boards, is there any tutorial for that.

    Thanks,