Electronic – How to identify Pin 1 on a chip with no corner mark


I am trying to identify Pin 1 of MAX3222E, the TSSOP variant (See Page 16 of datasheet), but it doesn't have any corner mark!

Could someone suggest how to identify Pin 1 in this type of situation?

I don't have a high-res camera on me right now, but I do have the chip in front of me, so here's a drawing of everything I see on top (the + sign is just part of the full name MAX3222EEUP+):

enter image description here

Best Answer

If you dig a little deeper on the Maxim website, there's a package drawing for this part.

Pin 1 is clearly indicated.


Note 8 says: "MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY", which means AAAA is boilerplate text.

Essentially, if you can read AAAA, pin 1 is lower-left.

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