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ADS1262: ADS1262

Anuja Mehendale
Prodigy 120 points
Part Number: ADS1262
Other Parts Discussed in Thread: REF5025

We are intending to measure +/- 2.5V signal. VDD is connected to +5V DGND to AGND. AVSS is connected to +2.5V AVDD is connected to -2.5V. AINCOM is connected to AGND. 

The reference is +2.5V connected to AIN0 and -2.5V connected to AIN1.

My question is is the above configuration correct to measure +/- 2.5V? The data sheet says you must connect AVSS and DGND toghther. But in my case AVDD is -2.5V and DGND is connected to AGND.

Thanks in advance.

Anuja

  • 0
    TI__Mastermind 42401 points

    HI Anuja,

    Can you draw a picture of your setup and post it here? You mention "VDD" and "AGND", neither of which are valid pins on the ADS1262, so I want to make sure you have the correct connections.

    Also, please note that connecting +2.5V to REFPx and -2.5V to REFNx gives you a 5V reference voltage, whereas you really only need a 2.5V reference in this case. You could use the ADC's internal 2.5V reference for this purpose, or something like a REF5025. You also want to make sure that there is some margin on the input signal compared to the reference so you don't provide a signal that is greater than full-scale.

    -Bryan

  • 0 in reply to Anuja Mehendale
    TI__Mastermind 42401 points

    Hi Anuja,

    Your last post is empty, I assume you tried to attach an image? Can you please reattach?

    -Bryan

  • 0 in reply to Bryan Lizon86
    Prodigy 120 points

    Hi Bryan,

    Can you see the schematic screenshot now?

    Thank you,

    Anuja

  • 0 in reply to Anuja Mehendale
    TI__Mastermind 42401 points

    Hi Anuja,

    Yes, this worked, thanks

    The connections look correct for the configuration you outlined (+/-2.5V input, +/-2.5V AVDD, +5V VREF +5V DVDD). Also, as I noted in my previous thread, connecting +2.5V to REFPx and -2.5V to REFNx gives you a 5V reference voltage, whereas you really only need a 2.5V reference in this case. You could use the ADC's internal 2.5V reference for this purpose, or something like a REF5025. You also want to make sure that there is some margin on the input signal compared to the reference so you don't provide a signal that is greater than full-scale

    I also could not see what the value of R22 is, but please make sure this value is sufficient to attenuate the input signal coming from the input amplifier (U8). I assume it is, but just wanted to clarify since R22 does not have a value assigned in the image you sent.

    If you have additional questions about your system, please start a new thread and we will be able to support you.

    -Bryan