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LMP91000: looking for webench sensor afe

CHETAN RAWAT
Prodigy 130 points
Part Number: LMP91000

Tool/software:

hi.

i am trying to design some sensor having electrochemical sensor as its basic module, giving current output in nano amperes. i got to know about the LMP91000 afe that can work well with this kind of applications. Again from there i came to know about the webench analog sensor afe designer which looked more promising for a successful design. now the problem is that i am unable to find this webench sensor afe designer. can anyone help me out in that. i had searched everywhere for it.

thanks in advance

  • 0
    TI__Expert 8985 points

    Hi Chetan,

    there are two software tools we have to offer for LMP91000, the LMP91000 EVM GUI, and the LMP91000 PSPICE model. I would use the EVM GUI to understand the basic functionality of the device and compatible chemical cells, and use the SPICE model to see how the LMP91000 will work in your bench setup.

    Regards

    -Alex Thompson

  • 0 in reply to Alex Thompson
    Prodigy 130 points

    hi Alex, thanks for your reply,

    now I have two more questions,

    1) from where do I get this PSPICE model??

    2) as I saw the datasheet of lmp91000, I got to know that the TIA gain can be adjusted by external resistor also. so what can be the maximum value of resistance that I can use? (My sensor's output is in nA) and what should be the value of external capacitor(if required with the external resistance)

  • +1 in reply to CHETAN RAWAT
    TI__Expert 8985 points

    Chetan,

    1. The PSPICE model is available for download on the product page:

    2. For external resistors, I would choose a resistor that will not cause the output voltage to exceed the chosen VDD or Vref. So for a cell that outputs a few nA, I would use an external gain resistor in the MOhms range to boost the output voltage. The external capacitance is only necessary if you are seeing noise and what to implement a low pass filter. I recommend setting up without a capacitor and with your chosen external gain resistor, and then see what value of cap you need to properly filter your noise. There are no hard and fast rules for chosing the external gain resistors and capacitors.

    Thanks

    -Alex Thompson

  • 0 in reply to Alex Thompson
    Prodigy 130 points

    Hi alex, i love your way of explaining things. Thanks a lot. Slight smile