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ADS8588S: Assistance in Selecting ADC and Op-Amp for SMU Project

Mahdi Al-Marhoon
Prodigy 10 points
Part Number: ADS8588S


Tool/software:

Dear TI Support Team,

My name is Mahdi T. Al-Marhoon, and I am a senior Electrical Engineering student at CU Boulder. I am currently working on my capstone senior project, which is a 16-channel Source Measure Unit (SMU). The specifications of our project are as follows:

  • 4 Quadrant Operation
  • 12 DUT Channels
  • 1% Accuracy
  • Voltage: ±12V
  • Current: ±5μA to 20mA
  • Range of DUT Resistance: 0.5Ω - 1MΩ
  • 4-Wire Measurement
  • SVMC, SCMV, and Sweep Modes

I have been searching extensively for an ADC and an Op-Amp that match our requirements but have not been able to find suitable components.

Our key requirements are:

  1. ADC: At least 16-bit resolution with an input range that can handle ±12V.
  2. Op-Amp: Must operate at 12V and support at least ±20mA output current.

I would appreciate any recommendations from Texas Instruments that meet these specifications. Your guidance would be invaluable in helping us select the right components for our project.

Thank you for your time and support. I look forward to your response.

Best regards,
Mahdi T. Al-Marhoon
Senior Electrical Engineering Student
University of Colorado Boulder

  • 0
    TI__Expert 4930 points

    Hello Mahdi! 

    Welcome to the TI E2E Forum! It is very exciting to hear about your capstone project and I would be happy to help! 

    The ADS8588S is definitely a good option for this, but we have a few other options of ADC's that have at least 16-bit ADCs capable of ±12V ( with and without some additional configurations)! 

    So I have some follow up questions: 

    • Have you designed your current and voltage paths?
      • Are you planning to use a current shunt? or what method were you thinking for current measurement?
      • Did you want the inputs to just go directly to the ADC? Typically we recommend to have additional circuitry to drive the inputs of an ADC, but there are some options where that part is integrated. 
      • What does your force path look like? 
    • You mention 16 channels, would you be ok with more than 2 devices (2x16-Ch or 4x8-Ch..etc.)?
      • is simultaneous sampling of both current and voltage per channel be something you would like to aim for?
    • Any consideration to speed/timing/response time?
      • Do you need a fast ADC or is a slower sample rate ok?
      • This would also be helpful when picking the OpAmp for your force circuitry as well.

    We have some resources that can help answer the questions, so hopefully it isn't too overwhelming! 

    This document talks about PLC monitors instead of SMUs, but there is some overlap with the voltage/current measurement side as well as the higher channel counts. It compares different types of ADC, inputs configurations, and some additional features some of devices have. Our Precision Labs ADCs series also covers this information 

    We also have this other resource that shows a an SMU in a block diagram that offers suggestions on devices for different functions as well as links to some of our reference designs.

    For the OpAmp selection, I would say for ±12V and ~±20mA there are a good amount of options as well. I would suggest looking into what kind of speed/response time, precision and stability you'd like to achieve and then we can either loop in my counterparts in the OpAmp team or you could post a similar question on the OpAmp E2E forum. 

    Best regards, 

    Yolanda