• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 45 subscribers
  • Views 222 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.

Original question:

PGA900: Load Cell design

ADS124S08: Load Cell design

SUMIT RANJAN
Expert 1985 points
Part Number: ADS124S08
Other Parts Discussed in Thread: ADS122C04

Hi Ti Team,

I can see ADS124S08 has 12 input. I have total 4 Qty of load cell so can i use this Ic so that i can connect total 8 Analog line from 4 Qty. of load cell.?

Excitation voltage will be common  for all all load cell and I believe AVDD is the terminal on which i have to give excitation voltage. Correct me if i am wrong.

Is there any other Ic, in which Analog voltage can have more than 5.5V? My load cell excitation voltage range is 5V~10V so if i will use Ic ADS124S08 then i can not apply more than 5.25V which will be on edge for Load cell. So, please suggest here.

  • 0
    TI__Guru** 112935 points

    HI Sumit,

    This sounds like it relates to this post:

    https://e2e.ti.com/support/data-converters/f/73/t/738936

    The ADS124S08 is an SPI interface device.  Is this the same application?  Is I2C no longer a requirement? You could connect four load cells to the ADS124S08.

    There are many methods of connecting a load cell to an ADC.  The best precision with the lowest issues of gain error and drift is by making the measurement ratiometric.  The ratiometric measurement is accomplished by making the excitation voltage and the reference voltage the same.  This will limit you to 5V.

    You can certainly excite the load cell with a higher voltage, but this will require that the input is within the input range for the gain applied.  To determine what method will work the best the desired resolution of the scale is required (for example 1g resolution for 50kg maximum load cell).  For this simple example 50000 noise free counts would be required.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Expert 1985 points
    Hi Bob,

    Still, I am using I2C. But benefit of this Ic is we can use single Ic which cost is almost same as ADS122C04. If i will use two ic as per requirement then cost will be around 9 USD but for single Ic ADS124S08 cost will be around USD 6.
    In this case, i need to use one I2C to SPI converter whose cost is around USD 1.5. Still i can save USD 1.5 which will have more impact in production.
    I know there will be development effort in this but that will be one time. So, I am exploring more in this case.

    You can suggest me cheapest solution and then i can see what other things required to make a complete solution over I2C.