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LMP91000 Working about 1uA Iuput Ozone sensor

min suk seoung
Prodigy 110 points
Other Parts Discussed in Thread: LMP91000

Hi 

I want to know about normal working of  LMP91000 in 1uA input Ozone sensor.

Setting conditions are as follows.

1. Road Resistance: 10 Ohms, Amp gain with external resistors: 330Kohm
2 Using the internal Ref: 5.0V / 2 = 2.5V
3. BIAS: Negative (default), 0%
4. FET OFF
5. OP_MODE = 3lead cell mode

In this condition, the LMP91000 output  do not come out exactly 2.5V, it comes out 2.64 ~ 2.2V from 1uA Ozone sensor in the absence of gas

Since more than 5uA Ozones sensor in the absence of gas comes exactly 2.5V output from LMP91000.

Dropping the accuracy about below the 5uA(1uA~5uA) for LMP91000?
Or am I setting wrong?
Setting is wrong, let me know how to set detailed.

I have confirmed that work well for 95% (more than 5uA Ozones sensor) sensor with LMP91000.

But, I have confirmed that does not work well for 5% (5uA below Ozone Sensor:1uA~5uA) Sensor with LMP91000

PIease, I want to receive a response within a quick time.

Best Regards

MS. 

  • 0
    TI__Genius 9655 points

    Hi MS,

    In order to answer to your questions, I need some clarifications:

    - can you provide me with the part number or datasheet of your Ozone sensor ?

    The voltage you read in abesence of gas is too much strange. Wich issource of the voltage supply of the LMP91000 ?

    When you select internal reference it means tha the supply voltage is used as a reference, so any noise on the supply is present at the output too.

    What do you mean for 1uA Ozone sensor and 5uA Ozone sensor ? Are you referring to the sensitivity of the sensor, such are 1uA/ppm and 5uA/ppm ?

    regards,

    Domenico

  • 0 in reply to domenyko
    Prodigy 110 points

    Hi Domenico

    can you provide me with the part number or datasheet of your Ozone sensor ?

     Ozone, SensoriC O3 3E 1 F

    Please send your E-mail to me, then I'll send the datasheet.

    Which is source of the voltage supply of the LMP91000 ?

    Receive the 5V  from VDD Pin. 

    Because you get to 5V VDD uses internal Ref. : 5.0V / 2 = 2.5V 

     

    When you select internal reference it means tha the supply voltage is used as a reference, so any noise on the supply is present at the output too.

    -> The same conditions (VDD used), the output value of only 1uA supply current is generated much noise.

     the output value of more than 5uA supply current is not generated noise.

     

     What do you mean for 1uA Ozone sensor and 5uA Ozone sensor ? 

     1uA supply current Ozone sensor and 5uA supply current Ozone sensor

     

    Are you referring to the sensitivity of the sensor, such are 1uA/ppm and 5uA/ppm ?

     Yes, 1uA/ppm and 5uA/ppm

     

    Please reply if further inquiries.

    regards,

    MS

  • 0 in reply to min suk seoung
    TI__Genius 9655 points

    Hi MS,

    I've read the application note of the Sensoric sensors from Cictytech. For the O3,3E 1F, it is recommended to use a 100ohm Rload.

    The LMP91000 supports this value. A higher Rload reduces the BW of system and the noise.

    Please use it.

    regards,

    Domenico