• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 44 subscribers
  • Views 674 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

WEBENCH® Tools/ADS1232: ads1232

Gobinath P
Intellectual 545 points
Part Number: ADS1232

Tool/software: WEBENCH® Design Tools

Hello people ,

            In my project  I am using ADS1232 .Input source voltage is 10mV , REF Voltage  is =5V ,I got output but ouput voltage is not perfect little deviation.please help me to fix the problem

example :±0.4 mV Deviation

           Input voltage -5mV

           Output voltage - 4.6 mV or  5.4 mV 

                                        thank you

  • 0
    TI__Guru** 113765 points

    Hi Gobinath,

    This most likely is noise.  It could be power line-cycle/EMI/RFI noise picked up on wiring.  Load cell wiring should be shielded and properly terminated as any noise will be gained up by the ADS1232 PGA.  You should also have a low-pass filter at the inputs to the ADC.  Please send me your schematic and layout and any raw data you may have to show the noise pattern for me to review.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Intellectual 545 points

    This is the schematic and layout file of my project.I have used differential pair route for ADC inputs  

  • 0 in reply to Gobinath P
    TI__Guru** 113765 points

    Hi Gobinath,

    Is this a 4 layer board?  I cannot tell what the ground looks like, but preferably you would want to have a solid ground plane.  If you are using polygon pours on a 2-layer board, this may not be sufficient for high performance.

    Are you using more that one ADS1232? I ask as the schematic and layout do not match.  Most likely you would benefit by having a low-pass filter on both the reference inputs and the analog inputs.

    The ADS1232 has the best performance when the reference voltage is the same as the excitation of the sensor.  This cancels noise and drift of the excitation/reference source. It appears that you are powering your sensor from 10V which means the measurement is not ratiometric and you will see additional noise and drift in the measurement.

    If the sensor is powered from 10V, you must make sure that the output of the sensor is within the common-mode input range for the ADS1232.  For a bridge type sensor (such as a load cell) the output will have a common-mode of 1/2 of the excitation voltage.  So for a 10V excitation the common-mode would be 5V in this case.  For the ADS1232 and at a gain of 1 or 2, this is within the common-mode range (AGND - 0.1V to AVDD + 0.1V).  However if more gain is applied then the common-mode input range is restricted and changes to AGND +1.5V to AVDD - 1.5V.  For a 5V supply the absolute input voltage at AINN and AINP must be within 1.5V and 3.5V with respect to AGND.

    Any noise on the cabling from your sensor to the input of the PCB has the potential for picking up unwanted noise.  This should be a shielded cable, and terminated to a ground point that is not the analog ground.

    Best regards,

    Bob B