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LMP91000: compatibility with Oxygen sensor PS1-O2-25

Takuchi
Intellectual 260 points
Part Number: LMP91000

Tool/software:

Hello,

I want to use this part with this Oxygen sensor from SGX, do you think it's compatible?

This is the sensor: PS1-O2-25: SGX - SGX Sensortech Sensor

I am not familiar with the sensor nor the potentiostat circuitry so I just want to make sure before purchasing the sensor as well as the EVM board.

Can you help me here please.

Thank you very much in advance.

  • 0
    TI__Expert 8885 points

    Hello Takuchi,

    I am not sure if that particular sensor will be compatible with LMP91000, but in our EVM software we have a non-exhaustive list of oxygen sensors LMP91000 is confirmed compatible with.

    Please note this list is not exhaustive, so the sensor you have identified may work just fine with LMP91000. But if you haven't purchased one yet, i would target one of the sensors on this list.

    Regards

    -Alex Thompson

  • 0 in reply to Alex Thompson
    Intellectual 260 points

    Hello Alex,

    Thank you for your answer. In our application, sensor size is a crucial aspect and all the above sensors are too big for our application.

    In my sensor, the recommended Rload is 220Ohm, can I add a series resistor to pin WE of the IC to increase Rload? Because from the datasheet, Rload is max 100Ohm:

    Also, the recommended bias voltage is -400mV to -600mV, can I achieve this with the IC?

    Thank you very much for your help.

  • 0 in reply to Takuchi
    TI__Expert 8885 points

    Takuchi,

    I don't believe the bias amplifier (A1) can output a negative voltage, so you may need to find a different oxygen sensor.

    I think adding another resistor to match the load requirement would be fine.

    Regards

    -Alex Thompson

  • 0 in reply to Alex Thompson
    Intellectual 260 points

    Hello Alex,

    In the datasheet, it says that the variable bias can be negative or positive, also in the register, there's a bit for setting the sign

    In my case, V(ReferenceElectrode) - V(SensingElectrode or WorkingElectrode) = -400mV to -600mV 

    I think this is achievable with programming the bias voltage to 20% of reference voltage of 2,5V.

    Can you advise here please.

    Thank you.

  • +1 in reply to Takuchi
    TI__Expert 8885 points

    Takuchi,

    Thank you for catching that, I overlooked that. I think that would work just fine then. Are there any other concerns with this sensor?

    Regards

    -Alex Thompson