LM358 problem

Discussion in 'General Electronics Chat' started by hazim, Apr 21, 2010.

  1. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    Hello,
    I'm using one side of LM358N as a comparator. A voltage divider using a photoresistor and a resistor connected at the inverting input, and a trimmer potentiometer at the non-inverting input. The datasheet says that Vcc can be as low as 3V. In my circuit Vcc=4V, and the output is 2.8V when high. I thought the IC is corrupted so I used another one... but it's the same. Is this normal since the supply voltage is low(4V)?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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  3. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    I have read the datasheet of the IC from onsemi. What I notice after I reviewed it is that at Vcc=5V and RL=2K, VOH min is 3.3V. I can compare the values in this case to mine but there is no affirmed accurate values I know...
    Thank you
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    Voh min=Vcc-1.5v.

    What's 4-1.5?
     
  5. kingdano

    Member

    Apr 14, 2010
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    got em.

    read the datasheets!

    they are there to help you understand how the device works, down to details you dont even want to think about.
     
  6. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    3.5V
    Where to find the electrical characteristic differences between LM358A and LM358N? if there is any or this suffix refers to the package only?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    I really hate to be sounding like a broken record here, but did you look in the datasheet? :rolleyes:

    If you don't like the datasheets you've looked at already, try ST Microelectronics' version.

    Here is their page:
    http://www.st.com/stonline/products/literature/ds/2163/lm358.htm
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Just for clarification:
    LM358 - basic part number.
    LM358A - An improved version of the basic part.
    N - a package suffix for either the LM358 or LM358A
     
    hazim likes this.
  9. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    1- I love electronics
    2- I love datasheets!
    3- I always read datasheets
    4- I read the onsemi and the national datasheets of LM358
    5- I confess that I don't understand everything in the many datasheets, but I want to learn what I don't know.
    Again, I really like to read datasheets, believe or don't believe :)

    Best regards,
    Hazim
     
  10. retched

    AAC Fanatic!

    Dec 5, 2009
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    Wow, I think hazim likes datasheets.
     
  11. hazim

    Thread Starter Active Member

    Jan 3, 2008
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    You are right :p
     
  12. kingdano

    Member

    Apr 14, 2010
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    he might in fact, like datasheets.
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    Why do most nOObs ignore the important details that are on datasheets?
     
  14. retched

    AAC Fanatic!

    Dec 5, 2009
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    The same reason desperate guys ignore the crazy in women. ;)
     
  15. kingdano

    Member

    Apr 14, 2010
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    you arent doing it right!

    its n00bs

    not

    nOObs

    you n00b!
     
  16. Audioguru

    New Member

    Dec 20, 2007
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    I am attracted to big bOObs, not skinny b00bs.
    Skinny b00bs have nothing (zeros or a vacuum) inside. (smilie)
     
  17. SgtWookie

    Expert

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    When Audioguru was a n00b, he whittled his datasheets out of a giant sequoia...
     
  18. Audioguru

    New Member

    Dec 20, 2007
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    When I was a nOOb, I had the Philips, Signetics and Motorola databooks.
    Then I moved and my next door neigbour worked for Fairchild and gave me lots of datasheets and application notes.
     
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