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ADS1256: Maximum data output rate on one SE Channel

Part Number: ADS1256

Hi,

I like to know what is the maximum sampling rate when I'm using only one single ended channel e.g. AIN0?

The datasheet says that the max. speed is 30kSPS. Is that the max. speed when I''m using all 8 channels or is it possible to get 30kSPS for one SE-Channel?

At the moment I'm using the following three commands to get my data. SYNC, WAKEUP and RDATA. But after the SYNC command the DRDY goes high for 0,21ms and I have to wait for it to go down.

Is it possible to speed that up?

Hope someone can help and thanks in advance.

Felix

  • Hi Felix,

    Sampling a single channel continuously (without MUX'ing or synchronizing) will provide a maximum data rate of 30 kSPS (assuming a 7.68 MHz clock). If you need to MUX or start/stop the conversion process then the internal digital filter will reset and the first conversion result will be delayed to allow the digital filter to settle (@ 30kSPS, you'll notice that the first conversion result appears after about 5 conversions periods - this is the SINC5 filter performing moving averages on the data).

    You can change the external clock frequency to make the ADC go a little bit faster. The maximum clock rate is 10 MHz, so you could potentially get a continuous data rate of 30kSPS * (10/7.68) = 39.06 kSPS.

    For more information about filter settling, take a look at: e2e.ti.com/.../delta-sigma-adc-digital-filter-types-sinc-filters
  • Hi Chris,

    thanks for your fast reply, That helps me a lot.

    Best regards,

    Felix