Optocoupler Pins

Other Hardware General Electronics
1

I feel like an idiot asking this question, but I'm having trouble identifying the pins on an optocoupler.

Here's the link to the datasheet (Google Docs): http://docs.google.com/viewer?url=http%3A%2F%2Fwww.optekinc.com%2Fdatasheets%2FOPIA1210A.pdf

Below is the image of the optocoupler. The datasheet says that Pin 3 should have an E [Page 2, bottom left chart]. If you look at the drawing on the datasheet, it shows the position of Pin 3 from the top view. This doesn't match up with my image no matter how it's rotated.

Thanks for the help!

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2

Don't look for the E look for the dot/dimple. It's at the bottom-left of your picture and it identifies pin 1.

--
The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected

3

Okay. That clears it up. Thanks RuggedCircuits!

4

It would help if you supply a link everyone can see instead of having to sign up to look at.

While RC is correct it could be that while dot is pin 1 the one with E on it could be pin 3 if they are labeled cross wise. That is pin 2 is vertically opposite pin 1 and pin 3 is back on the other side. I know this is not conventional but these sort of things do occasionally occur.

5

Page 2 of the linked data sheet shows the pin numbering with the same orientation as the photograph at the top of this page.

http://www.optekinc.com/datasheets/OPIA1210A.pdf

If the dot is pin 1...

4 3
1 2

Have you tried hooking it up to something to test? :slight_smile:

6

The E in the data sheet refers to the fact that it is the emitter, not that there is a letter E printed on the package.

7

I bet that Mike knows why ICs have the pin numbers going counterclockwise! Even if he's not as old as I am :slight_smile:

8

But they are not numbered counter-clockwise. You must be looking at the top instead of the bottom as anyone as old as you (and I) would normally do.

Don

9

@floresta, you're right.. it's counterclockwise looking from the top.

But the really arcane question is: "Why did the IC manufacturers start making all their data sheets showing their devices from the 'top', instead of from the bottom where the pins stick out, like all the previous amplifying devices"?

I bet young people think these are really stupid questions :roll_eyes: