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differential Buffer recommendations

Drake Jest
Prodigy 240 points
Part Number: ADS131M08

I would like to read up to 5volts with this ADC my initial design involves having a voltage divider with each channel looking like this.

I would like to explore a buffer alternative, may you recommend a good buffer IC to pair with this ADC, so i can have something to set as a baseline?

Thank you very much

  • 0
    TI__Guru* 92715 points

    Drake,

    Can you please re-post with the image? It didn't make it into the thread.

    When you are posting with images, you cant use the copy/paste (ctrl-c/ctrl-v) method to insert an image. You need to use the picture icon to select an image to insert it into the post.


    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 240 points

    Apologies for the 2 days late reply,

    Here is the schematic. I think i did it correctly, on me though for not noticing it in the posted post

    I based this circuit on the example circuit given by the datasheet, the TPD2E1B06 is just an ESD protection IC.

    Thank you.

  • 0 in reply to Drake Jest
    TI__Guru* 92715 points

    Drake,


    Is there a reason you want to have an active buffer alternative? Depending on the input signal, this voltage divider should work. A buffer could add additional offset and gain error (and the drift that each might have). Also, you'll need a buffer for each of these channels, so that would likely be 8 devices all in a tight layout area.

    What is the range of the input signal? I assume that you're measuring a signal that's ±20V. What voltage supplies are available? Right now, you'll need the +3.3V supply for the ADS131M08, but do you have a ±15V supply for an instrumentation amplifier. Few instrumentation amplifiers have attenuation, so you might need some sort of 

    Also I noticed an ISO_GND label on the schematic, is this the same ground as the ADC? Note that the input signal should be within the input range of the ADC, that likely means that they should share a common ground node.

    Can you share more of your schematic? I'm not sure what it is that you're measuring and it might be helpful for a recommendation.


    Joseph Wu