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Original question:

Analog front end design for electrochemical gas sensors

LMP91000

Frederic Griffe
Expert 1745 points
Other Parts Discussed in Thread: LMP91000, ADS1243, LMP90100, ADS124S08

Hello,

I am designing a gas sensing device with the LMP91000 AFE.

The device will have 4 sensors and 4 LMP91000 AFE.

The amperometric gaz sensors are delivering a very low current : 5nA / ppm

I need a 4 channel single ended ADC wich can also be configured as a 4 channel differential inputs (so 8 channels in total).

Which ADC would you recommend, ADS1243 or LMP90100 or any other ?

Best regards.

FG

  • 0
    TI__Genius 9675 points

    Hi Frederic,

    This is a temperature sensing forum, for ADC recommendations I will move your post to the correct forum.

    The LMP91000 supports Chemical Cells gas sensitivities over a range of 0.5 nA/ppm to 9500 nA/ppm so the low current of 5nA/ ppm is within range. Depending on the Transimpedance amplifier selected, the output step voltage proportional to the cell current will vary.  Although I suspect that with both of the parts being 24-bit ADC's, they would have more than enough resolution for your application.

    I suggest using the WEBENCH tool found on the LMP91000 product folder for configuration of the device.

    Jalen

  • 0 in reply to Jalen Tate89
    TI__Guru 50551 points
    Hi Frederic,

    I would recommend taking a look at the ADS124S08 family of devices.

    The ADS124S08 is our newest device in this space; as such it represents the best of our technical capabilities and has a plethora of integrated features. The price is low for the excellent DC performance, low noise, and the ADS124S08 VQFN package at 25 mm2: 5 x 5 is very small. There is also a lot of supporting documentation for the ADS124S08, which can be found here: www.ti.com/.../technicaldocuments