Difference between NE555 and LM555CN timer.

Discussion in 'General Electronics Chat' started by Lightfire, May 21, 2011.

  1. Lightfire

    Lightfire Thread Starter Active Member

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    Hello,

    I recently purchased a timer somewhere.:pI put in the paper (because I'm not the one who purhcased:D) 555 Timer (NE555). Is that correct? But they keeps giving me LM555 CN timer instead. Why? Are they the same?

    THANKS!!!!
  2. Kingsparks

    Kingsparks Member

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    Yes, basically Different manufacturer. Google 555 Datasheet and it will give you all the information you need.
  3. debjit625

    debjit625 Active Member

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    Also low power versions of 555 are made like ICM7555.
    Their is a dual version of 555 like 556 which have two timers and 558 is the quad version i.e it have four timers.
  4. ErnieM

    ErnieM AAC Fanatic!

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    Sorry to say it is NOT correct.

    Checking the NPX website (they bought Signetics) there are 8 different types of 555's available, and to make it clear to your purchasing department you should pick one complete part number (or several alternates) and not ask them to guess what criteria you left out of the part number you really just made up.

    Also tell then what company that part number is from. Different companies can have the same part number for different parts, or different numbers for equivalent parts.

    Parts can come in many different package styles you don't want people to guess which you intended.
  5. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    What you refer to as a low power 555 is not a 555. It is a CMOS 555, and has major, major differences in characteristics. It's drive is weak, it can go from 2VDC to 18VDC, and basically is just enough different from a classic 555 as to be considered a different part, as in many cases they are not interchangeable, mostly due to drive characteristics and the resistors used to set the 1/3 and 2/3 voltage points.

    As with the 555, there are many companies making the CMOS 555, with different part numbers. Radio Shack sells the TLC555, the TI version of the chip. Due to minor variations in process the CMOS chips can have variations in performances and speeds, but mostly they are interchangeable with each other, just like a standard 555 is usually interchangeable between manufacturers.

    The 558 is completely different altogether, and was only inspired by the 555. In no way is it a quad 555, unlike the 556, which has a 1 to 1 pinout corespondent and is a true dual 555.

    To the OP:
    As long as the part is a DIP style package you will be OK.
  6. nbw

    nbw Member

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    That's a good summary of my favourite IC there Bill!
  7. nbw

    nbw Member

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    "Like the sands through the hourglass, so are the 5-5-5s..." :D

    Attached Files:

  8. Lightfire

    Lightfire Thread Starter Active Member

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    But as you may see on the "Parts Required" it said that it should be NE555. Now, I am worried that it might not work (the project will not work) if I will use LM555 instead. Or what? Help?

    Thanks
  9. Lightfire

    Lightfire Thread Starter Active Member

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    Please take a look at my attached image if my time numberings was correct.

    THANKS!

    Attached Files:

  10. nbw

    nbw Member

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    I'm sure you'd be fine using an LM555 in place of an NE555 - I have a mix of both in my toolbox. As Bill pointed out ICM7555s are a different kettle of fish.
  11. debjit625

    debjit625 Active Member

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    Can yo explain it more,as far I know the most low power version of 555 is ICM7555,they have the same pin config.. and the trigger and threshold voltage reference point is also same,I dont find much difference over the interface.Of course as it is a low power version it will not sink or source current like 555.

    Here is the datasheet for 7555 and its function or truth table complements the 555's function table.

    Datasheet for ICM755 : http://www.intersil.com/data/fn/fn2867.pdf

    No here is how it should be...
    [​IMG]

    Good Luck

    Attached Files:

  12. debjit625

    debjit625 Active Member

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    Catapult another thing, the way I showed the numbering of the pins for IC 555 ,it applies to almost every IC with DIP.You start with the notch or dot mark of the IC and you count down to the bottom pin, then you move to the other side and start counting from the bottom pin to the top pin.

    You can read this ,the section "Orientation and lead numbering" in
    http://en.wikipedia.org/wiki/Dual_in-line_package

    Good luck for your 555 project.
  13. Audioguru

    Audioguru New Member

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    Lightfire,
    You should have a datasheet for every IC that you use. The datasheet shows the pins and all the spec's.
    I get datasheets from www.datasheetarchive.com where I can select a datasheet from many manufacturers of the same part.
  14. Lightfire

    Lightfire Thread Starter Active Member

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    Thank you very much debjit625.
  15. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    The part is the same. As a rule of thumb, all 555's can swap out OK, and all CMOS 555's can swap out. I gave you an attachment on another thread that showed it pretty well, I'll post it here too.

    Attached Files:

  16. Lightfire

    Lightfire Thread Starter Active Member

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    Okay. Thank you.

    Now, please help me with this pls. :http://forum.allaboutcircuits.com/showthread.php?t=54805
  17. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    Sure, start another thread and I'll go into more detail.
  18. magnet18

    magnet18 Well-Known Member

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    What? No 4013?!
    flip flop anonymous?
  19. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    Naw, I built one with a dual 555 (joking).

    But then there is the 74C72, 74C73, and 74C74 (too lazy to look up which one is closest).
  20. Kingsparks

    Kingsparks Member

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    Bill very nice illustration on chip pin out. Thanks, I'll add that to my library.

    By the by, I use the same source for datasheets as Audioguro listed but another I find just as good and sometimes faster is; http://www.datasheetcatalog.com/. Then again sometimes nothing turns up on real old numbers. That's for another thread though.

    Thanks again
    Roland
    :)
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