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AD5940 Self Test RE/CE

I use the RE/CE option for feedback to make 3 terminal measurements in standard operating mode.  I'd like to be able to do a self-test where I do 2 terminal measurement of the RE/CE terminals.

Is this possible?  It looks like the N and T switches can't do either CE or RE, but can I push it through the crossbar in a different way?

No real accuracy requirements in this self-test mode, so it's fine if it has to route through extra internal resistances / etc.

  • Hi,

    The AD5940_impedance example does 2 electrode impedance measurement.

    Switch settings:

    .DswitchSel = SWD_CE0,
    .PswitchSel = SWP_CE0,
    .NswitchSel = SWN_AIN1,
    .TswitchSel = SWT_AIN1

    If you are using AD5940ELCZ eval board, you may set the jumpers as below:

    JP9=JP10=JP11 = Position B (pin 3-4)

    You will obtain the impedance output magnitude as

    6.8KOhm if JP6 = Position A,

    or 750Ohm if JP6 = Position B.

  • Sorry, this does not answer my question.

    For the majority of the measurements I'm using 3 terminal mode.  This uses CE, RE, and AIN1.

    I want to be able to know if CE or RE have failed in some way.  Therefore I want a second type of measurement that does a two terminal measurement between CE and RE

    I was surprised that I could not directly measure CE to RE on the analog mux and would like to know if there is still a way to take this measurement by some other means.  I had assumed that this type of self test would be used for most 3 terminal setups, and was surprised that it wasn't directly supported.