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| Where is pin #1 for NE555P |
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| fixit7:
I looked at the data sheet for this ne 555p chip. I can not figure out where the pin locations are.? The picture shows a half circle on the chip which tells me nothing. https://www.dropbox.com/s/fitler9s3jt0i64/NE555P.jpg?dl=0 As in where is pin #1 in my picture? Thanks, Andy |
| Howardlong:
The circular indent in the package points you towards pin 1, in the traditional orientation package diagram of DIP, SOIC and SSOP packages, pin 1 is almost always shown top left. Thus, the two traditional standards for DIP are a marker at the top or a marker at the top left. Irrespective, if the chip is oriented with its marker to the top (or top left), pin 1 is ALWAYS at the top left. To be clear in your picture’s orientation, which is at 90 degrees to a standard pinout diagram, the top row of pins is 8 7 6 5 Bottom row is 1 2 3 4. If you turn your picture clockwise 90 degrees, the marker is at the top left, the same a standard DIP pinout diagram. Edit: this is an interesting noob question, because it’s one of those things “everyone knows”. Except they don’t. Edit 2: added some more details, I can’t help feeling my pudding is over egged now. (What’s more frustrating is that for some packages, manufacturers sometimes show you the view from the bottom, not the top. I have never seen this for DIP though, markings are always shown from the top.) |
| james_s:
I remember having this specific problem when I was a kid. Even the otherwise excellent Forrest Mims book I had did not show this detail as I recall and the internet was not a thing then so it was not easy to find the answer. It's something that is very simple once you know it, but without knowing that pins count up counter-clockwise around the IC from the lower left corner it is not obvious. And I think the above answer has an error, looking down on the top of the IC pin one is the *bottom* left, not the top. |
| Howardlong:
--- Quote from: james_s on May 06, 2019, 08:41:19 pm ---. And I think the above answer has an error, looking down on the top of the IC pin one is the *bottom* left, not the top. --- End quote --- I may be misunderstanding, are you referring to this? “in the traditional orientation package diagram of DIP, SOIC and SSOP packages, pin 1 is always shown top left.” Or this? “If you turn your picture clockwise 90 degrees, the marker is at the top left, the same a standard DIP pinout diagram.” Or something else? |
| 6PTsocket:
With the notch up, looking at the top of the chip, pin 1 is to the left of the notch and the numbers go CCW around the chip. If it is an 8 pin chip, pin 8 is on the other side of the notch. Sent from my SM-G900V using Tapatalk |
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