AD8137 Configuration

Hello, I'm trying to use an AD8137 as differential driver to an AD7799 ADC. The input of the of the AD8137 will be single ended with 0-5V input from a UV sensor IC. Basically the driver will drive a cable in differential mode back to my systems with the AD799. I'm having a problem understanding the topology needed for the AD8137 and AD7799. Currently my UV sensor looks as follows, but I'm not getting full scale values on the ADC. Any help getting the topology figured out and working would be greatly appreciated.



  • 0
    •  Analog Employees 
    on Aug 3, 2020 3:01 AM 4 months ago

    Hi,

    I think the parameters that limits your AD8137 to provide 0 to 5V to your ADC are the Input Voltage Range and the Output Voltage Swing.
    The AD8137 Input Voltage Range for your supply condition is upto 4V only.
    While the Output Voltage Swing will be +Vs - 0.55V. In your case, the output will be ~4.5V only.

    Your input is 0 to 5V. If you are not limited to +5V, I suggest for you to increase your +Vs to have 5V output.
    You could use +6V/-4V, +7V/3V. Just enough to have headroom.

    Also, I would like to introduce to you our Difference Amplifier Calculator Apps.
    You can download it here for free.

    From your design, using the Diff-Amp Calculator apps, it indicates that the output is clipped.

    Other useful system parameters are also displayed on the tool.

    Thanks and regards.