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ADS1256: Single ended buffer inputs- to system ground or 2.5V reference?

Ross Stanley97
Prodigy 10 points
Part Number: ADS1256

We are using the ADS1256 to digitize 8 channels of single-ended information. Because our system is 5 V full scale on all inputs, we are not using the PGA or inbuilt buffer. I read an earlier discussion that suggests capacitors may need to be connected to the inputs of the ADC to maximize settling time. Are they tied to system ground or to AINCOM, and hence the 2.5V reference?

Thanks:

Ross Stanley

  • 0
    TI__Mastermind 44680 points

    Hi Ross,

    Welcome to the TI E2E Forums!

    Generally, we recommend differential filter capacitors on the inputs to aid in anti-aliasing/noise filtering. For these capacitors to be most effective, you would want to connect them between your differential inputs...I know you said you're measurements were singled-ended, but the ADS1256 still measures everything differentially. Therefore, if you measure all of the inputs with respect to AINCOM, you would connect the capacitors between AINx and AINCOM.

    Connecting capacitors between each of the analog inputs and GND would be more for providing common-mode noise filtering, which likely isn't as much of a concern for single-ended measurements.

    Best regards,
    Chris