• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 2537 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

ADS1256 and sliding pot meter and load cell schematic

Kjetil Kristoffer Solberg
Prodigy 10 points
Other Parts Discussed in Thread: ADS1256, ADS1262, ADS1220

Hi, we are connecting a sliding pot meter (5kOhm) and a load cell to the ADS1256. However we are experiencing noise from pot meter. How should we connect these sensors to the ADS1256?, We use 3.3V og 5V on pot meter. And 5V on load cell. Surly there must be a way to minimize this.

  • 0
    TI__Mastermind 44680 points

    Hi Kjetil,

    Welcome to the TI E2E Forums!

    You are likely seeing noise coming from both the sensor and the voltage source used to excited the sensor.

    For sensor noise, about the only thing you can do is filter this noise, either in the analog domain (as a filter in front of the ADC) or in the digital domain (by reducing the ADC's data rate to increase filtering, or implementing an additional digital filter stage in the MCU).

    For noise coming from the excitation voltage, you can try to add filtering but typically you would also want to try to use this voltage source for the ADC's reference voltage. By doing so, this creates a "ratiometric" measurement. That is, the ADC's measurement result becomes independent of the excitation voltage (and to a degree independent from the excitation voltage noise) because the ADC measurement depends on the ratio of input voltage to reference voltage. Here is an example from www.ti.com/lit/ug/tiduac1/tiduac1.pdf.

    A similar configuration could also be achieved with the potentiometer. Just note that on the ADS1256, the maximum reference voltage is limited to 2.6V. Therefore, the 3.3V or 5V excitation voltage cannot be connected directly to the ADC but must first be divided down (and perhaps also buffered) in order to create this ratiometric connection. However, there are other ADCs (such as the ADS1220 or ADS1262) that would allow you to use reference voltages up to 5V and may simply this type of connection.

    Best Regards,
    Chris