How do I identify which pin is which on these tiny IC's?

elenore19 · January 21, 2011, 04:12:49 PM

These chips.
http://www.mouser.com/ProductDetail/STMicroelectronics/TL074CD/?qs=sGAEpiMZZMtCHixnSjNA6NYMOzdu7NqZapmkC5skLNY%3d
Along with these ones
http://www.mouser.com/ProductDetail/STMicroelectronics/TL072CDT/?qs=6fffrORWf5pLFxBvwrMMAA%3d%3d
I tried to take a picture of the 074 one, but all I have is my computer camera...Got one where you can barely tell that there is writing on the chip.

The only thing I can think of is that there is a small symbol that looks like it could be a logo of some sort, I can't tell what it is. Maybe that signifies Pin 1?

Thanks for the help guys!

-Elliot

slacker · January 21, 2011, 04:22:32 PM

Most chips have a small dot to mark pin 1.
If it's got no markings then hold it length ways so the writing is the correct way up and pin 1 is bottom left. I can't 100% guarantee this but it works for every IC I've ever seen.

elenore19 · January 21, 2011, 04:35:15 PM

Quote from: slacker on January 21, 2011, 04:22:32 PM
Most chips have a small dot to mark pin 1.
If it's got no markings then hold it length ways so the writing is the correct way up and pin 1 is bottom left. I can't 100% guarantee this but it works for every IC I've ever seen.

Alright, awesome. Thanks.
They have no markings, other than that strange logo/symbol thing I mentioned, which happens to be in the same corner as you're saying might be it.
Thanks!!

defaced · January 21, 2011, 04:37:22 PM

There's no little dot/indent like the data sheet says there should be?

elenore19 · January 21, 2011, 04:47:01 PM

Quote from: defaced on January 21, 2011, 04:37:22 PM
There's no little dot/indent like the data sheet says there should be?

Not that I can see. Looking extremely closely there MIGHT be a little indentation/dot thing in the same corner that we've been talking about. But the logo thing is printed right over it, so I can't tell if it's just the logo or something more.

Taylor · January 21, 2011, 05:01:32 PM

Notice that one long edge is beveled. The other isn't.

Check your datasheet, but the beveled edge will be pin 1-7 (for that 14 pin chip you're holding) and the non-beveled side is 8-14.

I noticed this too now that I've started using SMD opamps. They don't have any dot or notch. Slacker's right about the text, but the beveled edge is another way to know for sure.

PRR · January 22, 2011, 01:32:23 AM

> one long edge is beveled. The other isn't.

Hah! Nice tip, if I could see that small anymore.

Come to think of it, the old 0.1" SIP chips had a slant-top, same idea.

I bet the robot who is supposed to assemble this stuff has a one-bevel trough so the chips will only flow through the right way round. Makes a lot more sense than poking for a dent. Or trusting human attendants.

Cliff Schecht · January 22, 2011, 07:56:21 PM

The way the OP is holding the IC, pin one is towards the top left of the picture and 7 is bottom left, 8 is bottom right and 14 is top right. Every IC you ever run accross that uses just a flat beveled edge to indicate polarity will have pin 1 start in the same place (i.e. is the bevel is facing left, pin 1 is at the top).

News:

How do I identify which pin is which on these tiny IC's?