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ads1293EVM

Spira Matic
Prodigy 20 points
Other Parts Discussed in Thread: ADS1293

Hi,

I have problem with base line wandering.

When applying Test Ref zero signal on CH1, CH2, CH3, mean measured signal on all three channels is about 22 mV.

When applying +test and -test on + and - inputs of InA, respectively, mean measured signal on the three channels is about 460, 445 and 490mV, respectivelly.

The board is connected by USB, no external battery.

Please advise.

  • 0
    TI__Genius 14540 points

    Hi,

    We received your inquiry regarding the ADS1293 EVM and hope to get back to shortly with an answer.

    Thanks.

  • 0
    TI__Expert 3835 points

    Hello,

    The +test and -test signals should be around +200mV and -200mV respectively. These are not calibration signals, but can be used as self-test signals. Is baseline wandering observed while connecting to the internal test signals?

    Thanks,

    Sergio

  • 0 in reply to Sergio
    Prodigy 20 points

    Thanks Sergio,

    actually not.

    But we experienced that the board is very sensitive to electrodes quality. There are some other tricky EVM's behavior, but we hope we found the way it works and can handle it.

    For instance, when we apply zero signal to all inputs, sometimes we got 20mV but in next measurement roughly 0V (actually several nV).

    As I understood we must apply some external filter (hw or sw solution) to block signals below 0.05Hz, right?

    Thanks - Spira

  • 0 in reply to Spira Matic
    TI__Expert 3835 points

    Hi Spira,

    Right, the digital decimation filters in the ADS1293 provide a low-pass filter behavior, so blocking DC should be done off-chip.

    Best regards,

    Sergio