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EMG acquisition with ADS1294

Natalia Lopez
Prodigy 10 points
Other Parts Discussed in Thread: ADS1294, ADS1298

Dears

I'm trying to acquire EMG signals (only one differential channel) . Did I connect the RLD to a reference electrode in the patient?

Or can I leave the RLDs without connections? 

Thanks for your help

Natalia

  • 0
    TI__Mastermind 38745 points
    Hey Natalia,

    You should connect the RLD electrode to ensure that the voltages of the measurement channels to not experience DC drift which could cause the signals to leave the ADS1294's rails.

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    Prodigy 70 points
    Hi

    I am using ADS1298 for multichannel EMg acquisition.Should i leave RLD pins(RLDIN,RLDOUT,RLDINV) unconnected? If it has to be connected for reference electrode input then to which pin should i connect reference electrode?to VREF or to RLD pins.

    The unconnected pins should be set to AVDD level or it should be grounded if not in use.

    Thank you
  • 0 in reply to Kosha Patel
    TI__Mastermind 38745 points
    Hey Kosha,

    In general a patient drive signal is needed to set the common mode of the patient in biopotential applications. In some cases, people will connect the RLD output to the reference electrode and use that as a bias electrode.

    The VREF pin is the reference voltage for the ADC, which is completely unrelated to the reference electrode. A reference voltage is what an data converter uses to compare analog voltages to in order to create coherent outputs. That pin should be left alone if you plan on using the ADS1298's internal ADC reference.

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    TI__Mastermind 38745 points
    I should clarify... If you plan to use the internal reference, you should decouple the VREFP and VREFN pins with capacitors as it is recommended in the datsheet, but not use the VREF pin to drive any other circuits.