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ADS1255: Sampling rate.

Part Number: ADS1255
Other Parts Discussed in Thread: ADS1260

Hi team,

Can I use ADS1255 with a sampling speed of less than 315us?

If NO, could you introduce the device that can be used this condition with a 5V power or more?

Sincerely.
Kengo.

  • Hi Kengo,

    The maximum sampling rate of the ADS1255 is 30 kSPS at fCLK = 7.68 MHz.

    30 kSPS = 33us conversion time, so it is certainly possible to continuously measure signals at <315us. Note that the overall channel scan time depends on several factors including the input signal, external multiplexers being used, etc.

    You can also take a look at the ADS1260, which is the next generation version of the ADS1255. This ADC offers sample rates up to 40 kSPS (25us)

    -Bryan

  • Hi Bryan,

    Thank you for your reply.

    ADS1255 has the Settling Time(t18).
    Should I consider this?
    So, if I need signals at <315us, should I use 1.5kSPS or more?

    Sincerely.
    Kengo.

  • HI Kengo,

    Yes, this was my point about taking continuous measurements:

    "Note that the overall channel scan time depends on several factors including the input signal, external multiplexers being used, etc."

    The first conversion of the ADC will take t18 to settle - this is to allow the digital filter time to fill up. However, subsequent conversions will come out at 1/data rate, or in this case 33us using data rate = 30kSPS. This assumes you are continuously measuring a signal on the same channel. If there was a step input for example, the digital filter would need to fill up again and the conversion time would be subject to t18.

    If you were multiplexing through channels, then each measurement would take time t18 or possibly longer, depending on communication times, etc.

    So it really depends on what you mean by "signals <315us".

    Are you measuring one input continuously using the ADS1255?

    -Bryan

  • Hi Bryan,

    Thank you so much for your help.

    I understood about the settling time.

    I will continue to measure one input signal.

    Sincerely.
    Kengo.