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ADS124S06: Some design questions for ADS124S06/08...

Peter Tseng
Genius 5545 points
Part Number: ADS124S06
Other Parts Discussed in Thread: ADS1120, ADS1220, ADS114S06

Hi Sirs,

Please help on these questions.

Thanks.

1. While using single-end input, the int. PGA needs to disable or not? And if disabled the PGA, what the input impedance will be?   

2. For ratiometric measurement, is it ok to use the below connection?

3. If the connection of Q2 is OK, are there any solutions else with the same performance but lower cost from ADS124S06/08?

  • 0
    TI__Guru 62035 points

    Hello,

    1.) That is correct, the PGA input common-mode range doesn't include GND, which is needed for Single-Ended, GND-referenced inputs, so you'll need to disable the PGA for these types of measurements.  The input impedance is not directly specified and instead the absolute input currents are specified as shown in the spec table.  With the inputs buffers disabled, the input current is typically around 0.5nA.

    2.) The setup will work provided the inputs are within the input common-mode range of the ADC.  Double-check that the voltages that form meet the input common-mode range requirements.  An additional resistor is often added in series with the reference resistor to move the input common-mode to higher voltages if needed.

    3.)  Consider the ADS1220, it's a reduced channel device and is very popular.  There are also the 16-bit versions of both product families, the ADS114S06 and ADS1120.