STM32F401 64pin pin1 marking / orientation

Forum|Forum|12 years ago
May 20, 2014
9 replies
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Posted on May 20, 2014 at 11:52

I just want to place a STM32F401 64pin LQFP chip on my PCB, but to my surprise this chip has 2 pin 1 marking dots, on two diagonal corners. If I position the chip such, that I can read the text ''ARM STM32F401...'', then one dot is left bottom, and the other one is right top.

Anyone has an idea, which is the correct pin1 marking?

#stm-forum-junk-crash

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os_kopernika

Visitor II

Posted on May 20, 2014 at 13:36

You are right, the ''pin 1'' marker is sometimes problematic.

In every datasheet you can find the maker location on a to view of the case (Pachakage Characteristics chapter). Tripple check and ask someone else to confirm the location.

And fourth time: All Vss pins are internally shorted together.

schauer

Associate II

Posted on May 20, 2014 at 13:44

Without any warranty:

I'd expect the marking in the lower left corner, while the text is readable, the ''correct'' one on LQFP64 package.

One evidence might be the package characteristics within the data sheet along with the ''engineering sample marking''.

The STM32F401 I have here has only one marking though, maybe there is something wrong with the IC's?

flyer31Author

Senior

Posted on May 20, 2014 at 14:20

The ICs are fresh delivery from Digikey, so I think they should be ok and from mass production. The 2 markings look really very similar, I never saw something like this before on a LQFP package (just the marking right top is slightly larger, but only 10% - both of these markings seem to be remainders of the plastics forming machine, and they look very similar :) ). In the datasheet I did not find any useful information (at least not in the package description pages at the end... I just looked there). But in the Data brief for the 32F401 discovery PCB, there is a useful photograph of the final PCB - and from this I also think it should be the lower left marking.