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LM92: Comparator for temperature sensing application

Jonathan Geronga
Expert 7930 points
Part Number: LM92
Other Parts Discussed in Thread: TLV1701, TMP117

Hi Team,

I would like to request for your assistance if we have a possible TI solution for the customer request for a comparator for temperature sensing application.
He uses two pt1000 temperature sensors and need a comparator that can switch state (offset voltage) aprox. 0.1 mV

Following requirements:

V in 3-5V
offset voltage less than 0.2 mV
input signal to compare will be ~50mV

Here's the diagram of the customer:



Please let me know your inputs.

Thanks,

Jonathan

  • 0
    TI__Guru* 91206 points

    Jonathan - 

    here you indicate that you are needing to know when these two devices are 1 degree apart. Is that correct? 

    (from PT1000 LUT, the values you give for PT1000 resistance equal 20C and 21C)

    A comparator like the TLV1701 would probably work fine in your application. 

    the circuit above would switch when their levels cross, here I assume one PT1000 would be held exactly at 20C?  

    i simulated this, looks like it will work for you, too, if that is the behavior you are after. 

    if you hold one constant temp (20C) on the one PT1000, and just set comparator reference voltage for the voltage that would be seen at 21C and connect second PTC1000 to the comparator, it (the comparator) will trigger when it crosses 21C

    Do you need to use PT1000? Have you looked at TMP117? or our line of temp switches? 

  • 0 in reply to Josh Wyatt
    TI__Expert 7930 points

    Hello Josh,

    Thank you for your response and support.
    I will discuss this information you shared with our customer and I will let you know if this will resolve this request.

    Regards,

    Jonathan