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LMT01-Q1: LMT01-Q1 replacement for NTC

Jon Bilbao
Intellectual 1415 points
Part Number: LMT01-Q1

Hi guys,

can you comment on how robust against disturbances is the digital interface of LMT01-Q1 for long distance communication (~1mt) between sensor and microncontroller, compared to a regular NTC with analog output?

Regards,

Jon

  • 0
    TI__Mastermind 31650 points

    Hi Jon,

    Thank you for reaching to us. The LMT01-Q1 is a pulse train output, and I tested with the cable as long as 25 meters with or without shielded. There is no issue on communication for the microcontroller. However, it is sensitive to capacitance loading so choosing a low capacitance cable is recommended. Please refer to the datasheet chart section 8.2.1.3 where the output signal is compared with or without capacitance loading. In comparsion to regular NTC, it is required additional components to compensate the noise for long distance communication. The longer cable is the more resistance; therefore, there is voltage drop across the long cable in result of loosing the temperature accuracy.

    Hope this helps. Let me know if you have further question.

    Aaron

  • 0 in reply to Aaron Heng
    TI__Intellectual 1415 points

    Hi Aaron,

    thanks.

    let me clarify something: when you say 

    "required additional components to compensate the noise for long distance communication. The longer cable is the more resistance; therefore, there is voltage drop resulting of loosing the temperature accuracy"

    you mean that the NTC requires additional components and there is loss of temperature accuracy across the long cable, also with NTC? 

    this does not happens using the LMT, with digital interface? 

    Regards,

    Jon

  • 0 in reply to Jon Bilbao
    TI__Mastermind 31650 points

    Hi Jon,

    I'm sorry for the long delayed. To answer your first question, Yes. It doesn't happen to LMT as long as you keep the long cable with less than 100pF of stray capacitance. This pararistic capacitance only effect the signal rise and fall times not in accuracy.

    Let me know if you have further question.

    Aaron