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ADS1263: ADS1263

Manisha Parmar
Prodigy 80 points
Part Number: ADS1263
Other Parts Discussed in Thread: ADS1262, TIPD188

We need a stable & low drift converter with minimum of 100000 (1 Lakh) Counts and Data rate of minimum 300 SPS

We've selected this one (ADS1263)...

But I read the following statement on the Product page reference design... Now I'm confused... Being a 32 bit ADC it just gives 50000 counts....

"This precision weigh-scale reference design achieves greater than 50,000 noise-free counts of resolution. Offset and offset drift errors are nearly eliminated by ac bridge excitation. This design takes advantage of the high-resolution ADS1262 delta-sigma ADC."

Can someone guide who has Practically used this one...

What actual useful counts would I get at requirements ???

  • 0
    TI__Mastermind 40635 points

    Hi Manisha,

    Can you please let me know which reference design you are referring to? I would like to check it before answer your questions, thanks.

    Regards,

    Dale

  • 0 in reply to Dale Li
    Prodigy 80 points

    Thanks Dale,

    Plz go to the following link

    https://www.ti.com/product/ADS1263/toolssoftware

    scroll down & you will find

  • 0 in reply to Manisha Parmar
    TI__Mastermind 40635 points

    Hi Manisha,

    I apologized for missing your post. Thanks for providing more information.

    In this specific reference design, the reason to only achieves greater than 50,000 noise-free counts of resolution is, the full-scale bridge output voltage in this weigh-scale application is only 10mV. Standard Noise-free resolution is defined with full-scale input voltage range shown as below.

    Noise-free resolution = log2 [full-scale input voltage range/ADC peak-to-peak noise]

    I hope this information is helpful to you.

    Best regards,

    Dale

  • 0 in reply to Dale Li
    Prodigy 80 points

    Thank you Sir,

    But We need at least 100000 counts at 200 Data rate...

    Can you suggest any other ADC

     

  • 0 in reply to Manisha Parmar
    TI__Mastermind 40635 points

    Hi Manisha,

    The designed resolution in the reference design is 15.6 bits or 200nV regarding 10mV full-scale output of the bridge. An ADC with higher resolution(24-bit) is usually used to account for the loss of dynamic also the effect from all other components in the system is considered. ADS1262/1263 is a 32-bit delta-sigma ADC with low-noise, low-drift performance and integrated programmable Gain Amplifier (PGA). Also, the noise-free resolution on ADS1262/1263 is minimum 18.3 bits at 400 SPS, these make it a best ADC for high-end weigh-scale application. You can apply an EVM board to evaluate its performance as a starting point.

    Notice that the goal in the reference is 50,000 noise-free counts, however the measured result is 86,785 noise-free counts. To reduce offset error which is the largest error source, either calibration or ac-excited bridge measurement must be implemented. The drift error(offset and gain) can be removed by re-calibrating, limiting the temperature range or performing ac bridge excitation. Also, there are some other ways to minimize the noise and reduce the error in the system, averaging additional samples in post-processing, reducing ADC's data rate, eliminating the linearity and other error from the load cell, having a good pcb layout and so on.

    The Excel spreadsheet for error calculations can be found in the TIPD188 design file (TIDCAM8). The ADC error calculations are also explained in a TI Precision Hub Blog.

    Thanks&regards,

    Dale