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ADS1120-Q1: Questions

Ivy Jin
Expert 3415 points
Part Number: ADS1120-Q1

Hi team,

Could you please help give some comments about the following questions? Thank you!

My customer is using the ADS1120-Q1 in the project, the power supply is CR2032b, voltage 2v~3V.
The bridge parameters are:

  Piezo resistance：Min28kΩ，Typ33kΩ，Max38kΩ

     The Y/Z axis has a maximum range of 400G 

       Y-axis sensitivity：0.10mV/g/V

     Z-axis sensitivity：0.04mV/g/V

Q1:If ADS1120-Q1 can be wired as shown in the diagram below (REFP1, AVDD, DVDD to battery positive, AVSS, DGND, CLK to battery negative)?

Q2: Are the following calculations correct? Will the output of the detection bridge (±48mV) be satisfied when Gain=32, AVDD=3V?

Bridge output Vz=48 mV at 3V, 400G.

VIN (MAX) ≤ ±[(AVDD – AVSS) – 0.4 V] / Gain = ±(3V – 0.4 V) / 32= ±81mV

1 LSB = (2 * Vref / Gain) / 2 16 = (2 * 3 V / 32) / 2^16 = 2.86 µV

Q3: Is the 1LSB the minimum differential voltage that the ADS1120-Q1 can detect?

Regards,

Ivy

  • 0
    TI__Expert 6310 points

    Hi Ivy,

    Ivy Jin said:
    the power supply is CR2032b, voltage 2v~3V.

    Make sure that the power supply is above 2.3V for the device to function properly, as anything below this falls outside of the device's recommended operating conditions:

    Ivy Jin said:
    Q1:If ADS1120-Q1 can be wired as shown in the diagram below (REFP1, AVDD, DVDD to battery positive, AVSS, DGND, CLK to battery negative)?

    Yes this should work ok. As mentioned previously, both AVDD and DVDD should be above 2.3V to be within the recommended operating conditions. 

    Will the low-side switch (REFN1 to AVSS) be used?

    If not, then I suggest using REFP0/REFN0 and AIN0/AIN1 as the inputs in this case. This configuration might yield slightly better performance due to the input currents.

    Ivy Jin said:
    Is the 1LSB the minimum differential voltage that the ADS1120-Q1 can detect?

    Yes 1LSB is the smallest voltage increment that the ADC can detect, corresponding to 1 bit. 

    Ivy Jin said:
    1 LSB = (2 * Vref / Gain) / 2 16 = (2 * 3 V / 32) / 2^16 = 2.86 µV

    This is correct if your Vref / power supply = 3V.

    Best Regards,

    Angel