lm35 problem

Discussion in 'The Projects Forum' started by mah, Jan 20, 2014.

  1. mah

    Thread Starter Active Member

    Mar 15, 2010
    276
    2
    i use lm35 to measure the temperature surface of photovoltaic panel when i feed it with 2.6 v supply it give output 0.754 this is related to 75 °C when i increased the supply voltage to 4 v and more it give 0.44 v related to 44 °C
    Is that normal or i have defected sensor ?
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,087
    3,027
    4V is the minimum specified supply voltage. Below 4V, I wouldn't pay any attention to the output.
     
  3. praondevou

    AAC Fanatic!

    Jul 9, 2011
    2,936
    488
    What is the actual temperature?

    Line regulation is only specified between 4V and 30V according to the datasheet. At what voltage do you want to use the IC?
     
  4. mah

    Thread Starter Active Member

    Mar 15, 2010
    276
    2
    any voltage is available but i have doubts of output
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,087
    3,027
    Why? You've only cited one result (which is plausible depending on what you are doing with it) taken at the absolute minimum supply voltage. Try 9V and see what you get.

    By the way, it's just as easy to wire this wrong as any other component. Mine survived miswiring at 5V but not when I turned up the voltage. Double check before you do that.
     
  6. TANDBERGEREN

    Member

    Jan 20, 2014
    74
    4
    When powered with a too low voltage, the output will not be reliable.

    Give it a minimum of 5V and the output will be as specified.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    If you remove the supply altogether will you trust the voltage output?

    (There's a lower limit if you want reliable operation.)

    Ultimately, your validation testing should remove all your doubts.
     
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