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ADS1232 data rate

Stefano Infante
Expert 2320 points
Other Parts Discussed in Thread: ADS1232, ADS1220, ADS1247

Hello,

I have a simple question about ADS1232: its sample rate is 10/80 Hz, but is it for each channel (10/80 Hz each channel) or for both channels (5/40 Hz each channel)?

Thanks in advance,

Stefano

  • 0
    Expert 2320 points

    As I got no answer, maybe I should be more explicit in my question...

    I have to read the outputs of two load cells, and I need them to be sampled at 80/100 Hz. So I think to use ADS1232, which has an 80 Sps output, and the possibility to use an external oscillator in order to reach 100 Sps.

    Hence the question: by using ADS1232, will I be able to read 80 samples per second from each input, by simply switching the input multiplexer every time I see a converted sample?

    Or should I select the channel and then wait for the sample to arrive, thus "losing" half of the data rate?

    Every advice will be appreciated...

    Thanks,

    Stefano

  • 0 in reply to Stefano Infante
    TI__Guru** 113765 points

    Hi Stefano,

    Sorry for the delayed response.  The ADS1232 has a muxed input as opposed to having two simultaneous sampling converters.  This means you must alternate between the two and this will reduce the total throughput time to 1/2 of the given data rate assuming that you switch channels at the most optimum time.

    However, you will not truly achieve 40sps (assmuming you are using the 80sps data rate) as the digital filter is not single-cycle settling (where every conversion is valid following a mux change), but rather sinc3 where the first 3 data results is settling through the filter and the fourth is fully settled.  This is discussed on page 17 of the datasheet and demonstrated in Figure 32.  This reduces the throughput further.  This reduces the overall throughput when muxing two channels to 10sps even though the selected data rate is 80sps.

    You may be interested in taking a look at the ADS1247 or the ADS1220 which are both single-cycle settling converters and have faster data rates.

    Best regards,

    Bob B