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ADUCM350 current measurement 4-wire configuration

Hi,

I would like to know if its possible to measure the current going through the unknown impedance.

I'm using a normal 4 wire configuration (i.e. non-bioimpedance measurements), and I can successfully measure the impedance, but I would also like to know the current going through or the voltage across the impedance.

The user manual mentions a calibration routine for current measurement through TIA, but it says that it needs a current source. I've seen the example of the 4-wire Bio measurements and I assume that it's measuring the current through the TIA but this is considering the external AD8226.

Do I require external circuitry to get this extra information?

Thanks!

  • Hi,

    You can measure the excitation voltage and current directly with ADuCM350. Below is the figure from UG-587 page 366.

    You will connect switch to unknown impedance rather than Rcal. The theroy is same. You just need to set ADC MUX to P and N node.

    The current flow through unknown impedance(Rcal in this figure) is same as current flow through RTIA//CTIA(RTIA in parallel with CTIA). Set ADC MUX to RTIA, the measured voltage divide RTIA//CTIA is the current you want.

    Regards,

    Neo