Which is pin 1 on SOT23-6 (INA193)?

Discussion in 'General Electronics Chat' started by Jim_cliff11, May 13, 2016.

  1. Jim_cliff11

    Thread Starter New Member

    Sep 5, 2015
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    Hi all,

    I'm using an INA193 current sense amp soldered onto a SOT23 to DIP adapter board. However I'm unsure as to which pin is number one? And in what order?

    Picture attached. Please don't judge the soldering, rough and ready but it does the job for prototyping.

    image.jpeg

    Thanks,
    Jim
     
  2. dannyf

    Well-Known Member

    Sep 13, 2015
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    have you tried to read the datasheet?
     
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  3. jpanhalt

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    Jan 18, 2008
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    The lower left in your picture. Count from there CCW. The upper left is PIN5, as that device by TI or BB only had 5 pins according to its current datasheet.

    Have no idea about the blob of solder between Pins4 and 5, assuming it is an INA193.

    John
     
  4. atferrari

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    I doubt he did; otherwise he would have not needed to ask the question.

     
  5. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The datasheet normally shows a picture of the chip and the pins relative to the orientation of either (a) the text, or, (b) a dot molded into one corner, or (c) a bevel molded into one of the longer edges on the top of the chip. Read the datasheet. The datasheet will tell you exactly how it works for that specific chip.

    If it is not listed on the datasheet, you should buy chips from a different manufacturer.
     
  6. tracecom

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    Apr 16, 2010
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    Good advice...much better than just asking "Have you read the manual" which accomplishes nothing. Here's a snip from a datasheet I found with Google.

    INA193 Pinout.JPG

    Although I don't see a dot in the OPs photo, I assume that the part is oriented with pin1 at the lower left. If so, the blob of solder on pin 4 doesn't extend to pin 5 and does no harm.
     
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  7. Jim_cliff11

    Thread Starter New Member

    Sep 5, 2015
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    Thanks all, bar DannyF. What a daft thing to say. Of course I checked the data sheet, otherwise I wouldn't be asking in the first place.

    The dot shown on the data sheet does not exist on the chip as Tracecom pointed out. Jpanhalt was spot on with his answer.

    Thanks
     
    Last edited by a moderator: May 15, 2016
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Did you see the remark at the dimension drawing of the datasheet?

    ina193_pinout_drawing.png

    Bertus
     
  9. jpanhalt

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    Also, a quick search for INA193 revealed this:
    upload_2016-5-14_15-54-35.png

    Since the TS's device is marked BJJ, that gives you the orientation for pin 1.

    John
     
  10. WBahn

    Moderator

    Mar 31, 2012
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    The TI drawing for this part specifies that the Pin 1 Index Area is optional. Presumably this is because the missing pin makes the orientation unambiguous.

    While the solder blob shouldn't cause any problems with this chip, it is possible that the trace that serves the middle pin is connected to circuitry on the board that this goes to -- possibly as a trace routing saver predicated on the knowledge that this pin isn't used -- so it isn't entirely the case that the solder blob causes no harm (but that is likely the case).
     
  11. kubeek

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    Sep 20, 2005
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    When the part has three pins on one side, and two on the other, how do you suppose the part is oriented, even without having the #1 pin specifically marked?
     
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  12. WBahn

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    Not as daft as you might think -- the sad reality is that a very high fraction of people that ask these questions have not bothered to read the data sheet (in some cases they don't even know that such things as data sheets exist, which shows the extreme range of backgrounds that people come here with).

    What data sheet did you look at? The TI data sheet (and the BJJ seems to indicate that this is an actual TI part) very clearly shows which pin in pin one.

    http://www.ti.com.cn/cn/lit/ds/symlink/ina193.pdf

    Look at page six. While is shows a pin-1 marker, the far stronger indication is that the missing pin is located between pin 4 and 5. That's a HUGE hint as to which pin is pin 1.

    If you look at the mechanical drawing (another part of the data sheet you should always reference when trying to answer a question like this), which is the two pages back from the last page, you will see that it indicates that the pin 1 index area is actually optional.
     
  13. WBahn

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    As per the data sheet information. There's really no getting around that.
     
  14. kubeek

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    What I meant was when the datasheet says pin one mark is at the top left corner when the three pins are on the left side, how could you get lost when that mark is missing? It´s still the same three pins with or without the pin 1 mark.
     
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  15. WBahn

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    Ah. I thought you were asking the generic question of how you would determine which pin is pin 1 on an IC that has three pins on one side and two on the other.
     
  16. kubeek

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    And of course OP did read the datasheet, who is DannyF to even think of accusing the OP of not reading it?
    Jim, when someone asks you: did you read the datasheet? You should read it again, blush and say "no, apparently I did not read, or understand it enough". You definitely should not be answering "yes of course I read it what is your problem". A bit of humility gets you a long way.
     
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  17. WBahn

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    A point that can be (and does get) pointed out to many of us around here from time to time.
     
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  18. Jim_cliff11

    Thread Starter New Member

    Sep 5, 2015
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    Sorry chaps, yes you seem to be right.

    Thanks for the help, point noted
     
  19. atferrari

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    Jan 6, 2004
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    And pin 1 as well! A happy end. :)
     
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