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ADS1298ECGFE-PDK: ADS1298ECG FE -PDK EVM

vasanth kumar78
Intellectual 955 points
Part Number: ADS1298ECGFE-PDK
Other Parts Discussed in Thread: ADS1298, ADS131A04, ADS131E08

Hi

I am going to use ADS1298ECG FE PDK EVM, the following are the querries

1.what is range of  maximum frequency and signal voltage  range can be given to the Input electrode signal ( ADS1298ECG FE EVM) ?

2. This evm, shall I use for 50hz to 60hz  Input electrode signal?  but in user guide manual , attenuation of  50 and 60HZ Input electrode signal is doing to avoid interference with power supply frequency.

3.is their any feature to change attenuation settings in this EVM, let me to know.

  • 0
    TI__Mastermind 49571 points
    Hi Vasanth,

    Thanks for your post and welcome to the forum!

    1) The maximum input frequency is limited by the Nyquist theorem which states that you must sample at least 2x the input frequency. Since the max sample rate is 32kSPS this means that 16kHz is the maximum input frequency. The maximum magnitude is set by the power supply and reference configuration. This post explains: e2e.ti.com/.../379380

    2) I'm curious, what type of signal would have a 50-60Hz frequency coming from an electrode? For ECG/EEG there are challenges with 50/60Hz noise coupling onto the skin and distorting the measurement. As stated in section Post Processing Filters Feature of the user's guide. This is configurable.

    3) There is an integrated & configurable digital filter which is covered in 9.3.2.4 Digital Decimation Filter of the datasheet and there is an RC filter on the inputs to filter out the high frequency signals that are aliasing back into the sample range.
  • 0 in reply to Alexander Smith
    Intellectual 955 points
    Thank you Alex, my query is relating to rejection of 50-60hz differential input signals at the electrodes,it is mentioned that the ADC would attenuate signals having this frequency as they are power frequency noise. We are using this for magnetic flowmeter where signals induced have similar amplitudes as that of ECG and frequency is 50 -60 Hz (for avoiding galavanic action at the electrodes).

    Please suggest if we could bypass this filter that attenuates 50-60Hz frequency input differential signals and if yes please give steps to do the same in the EVM.
  • 0 in reply to vasanth kumar78
    TI__Mastermind 49571 points
    You are welcome Vasanth!

    As per the datasheet: "The sinc filter has notches (or zeroes) that occur at the output data rate multiples." Please see figure 52. Where the notches occur are based on your output datarate and input frequency.

    From the userguide: 3 - Post Processing Filters Feature
    The Post Processing Filters Features controls provides a low-pass, a 50Hz/60Hz notch, and a highpass digital filters for post-processing the data from the ADS1298. To activate each filter, the Enable checkbox should be checked. To disable the filter, the Enable checkbox should be unchecked. Any combination of the three digital filters can be used by enabling the respective filter.

    You may also be interested in the ADS131E08 or ADS131A04 devices since you are not using this for a medical application and may not take advantage of some of the features.