13
\$\begingroup\$

Where is pin #1 on this IC?

It seems to have a line and a dot. The dot doesn't seem to line up with a corner pin though.

Chip is a INA210AIDCKR.

enter image description here

\$\endgroup\$
3
  • 4
    \$\begingroup\$ While the datasheet does show a dot, I'm pretty sure the line is indicating that top left is pin 1. I will admit that that is a needlessly vague diagram in the datasheet however. \$\endgroup\$ Commented Jan 26 at 5:04
  • 1
    \$\begingroup\$ Great picture, well done \$\endgroup\$
    – Bryan
    Commented Jan 26 at 22:34
  • 1
    \$\begingroup\$ None of that looks like a real dot to me. The line at the top of the image, however, is definitely the thing you should pay attention to. \$\endgroup\$
    – Adam Haun
    Commented Jan 26 at 22:40

4 Answers 4

14
\$\begingroup\$

Generally, when the text/print is the correct way up, bottom-left is the pin-1. This applies to QFP/LQFP, QFN, SOT, DIP, SOIC, SOP and maybe some other packages. For your question, it's the top-left according to the picture.

\$\endgroup\$
4
  • 6
    \$\begingroup\$ Oh really? Is this just your experience or is there an "official" norm/convention for this? \$\endgroup\$
    – tobalt
    Commented Jan 26 at 7:39
  • 1
    \$\begingroup\$ Have definitely seen some odd conventions before. No examples offhand unfortunately. Incidentally, PLCC does (or may?) start in the middle of a row, just to throw everyone off (good riddance I suppose?). \$\endgroup\$ Commented Jan 26 at 8:42
  • 1
    \$\begingroup\$ @tobalt sorry for the misunderstanding caused by my wording. Of course it's not an official thing, just like the fact that pin numbering direction is just a tradition. \$\endgroup\$ Commented Jan 26 at 8:54
  • \$\begingroup\$ @TimWilliams oh yeah, PLCC starts from the middle. I even forgot the existence of it, haven't seen one for years. \$\endgroup\$ Commented Jan 26 at 9:07
11
\$\begingroup\$

In your picture, pin 1 should be top left. (I have never seen any ICs with a bar line that does not start on the first pin and ends on the last pin.)

The datasheet specifies pin 1 in relation to the index area:
enter image description here

\$\endgroup\$
1
  • \$\begingroup\$ +1. The "horizonal line" convention is extremely common in SOIC parts. \$\endgroup\$ Commented Jan 27 at 12:44
2
\$\begingroup\$

I measured resistance between pins 1 and 4 (assuming top left is pin #1) and got a resistance of 1 or 2 MOhms (I can't remember now). Pins 3 to 6 were not connected. So this supports top left being pin #1.

Thanks for the input.

\$\endgroup\$
1
\$\begingroup\$

There is also a dot in the bottom right corner.

If it were my chip I would check VSS and VDD pins with a diode tester to be sure. Or you could try to measure the internal resistors.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.