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ADS1262 data rate questions

Mo.
Mastermind 22165 points
Other Parts Discussed in Thread: ADS1262

Hello Team,

We received the below question from one of our customers on the ADS1262 device:

The datasheet says, that a data rate of up to 38.4 kSPS ist possible. This seems to be valid for continuous mode only and not for pulse conversion. I could not directly find this information in the data, it was more lees an assumption looking at figure 107 (datasheet SBAS661B - FEBRUARY 2015). Out measurements show, that pulse conversion seems to be limited to something around 4 kSPS. Is this something you can confirm?

Unfortunately we have already integrated many of those converters in our hardware, so it would be good find a workaround allowing me to have 38.4 kSPS. Is there any way to have this sampling rate using the pulse conversion mode?

Can you please advise?

Kind Regards,

Mo.

  • 0
    TI__Mastermind 44680 points

    Hi Mo,

    Due to the digital filter's settling time, the first conversion result is always slow...This is true for both continuous mode and pulse conversion modes.

    The digital filter is effectively a moving average filter, trying to average the previous 5 conversion results (that is, for the SINC5 filter). Therefore, it takes roughly 5 conversion cycles for the digital filter to produce a valid output at the 38.4kSPS data rate; however, from then on the filter provides a result at the normal data rate.

    In pulse convert mode, the ADC resets the digital filter with each conversion, so the effective data rate is roughly 5 times slower than the nominal data rate. Table 17 shows the actually conversion time, so take 1/td(STDR) to calculate the effective data rate in pulse convert mode.

    To get the 38.4 kSPS data rate, the ADS1262 needs to operate in continuous conversion mode. Would it be possible to allow the ADC to continuously convert, but ignore the data when it's not needed? This way, the customer could simply read the ADC data as needed.

    Best Regards,
    Chris

  • 0 in reply to Christopher Hall
    TI__Mastermind 22165 points
    Hi Chris,

    Thanks a lot for the clarification. I will inform the customer about this.

    Kind Regards,
    Mo.