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Topic: No pin markings... (Read 1 time) previous topic - next topic

thegeekway

Whats the general process for determaining pin 1.  Its a 74HC4050D with no marking on the body at all, the datasheet has no help and Farnell tech support keeps copy pasting bits of the datasheet ;) (Now they want photos).

Anyone used this part, its a SOIC16 package.

Thanks

Graynomad

There has to be something, often a painted strip along one end or tiny dimple on one corner.

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

thegeekway

Thats what I thought, but nothing.  Had it under the stereo microscope and can't find anything.  Guess its going to be trial and error.

Graynomad

Look at the bright side, there are only two options, be thankfull it's not a quad pack.
Rob Gray aka the GRAYnomad www.robgray.com

thegeekway

That cheered me up :D  Glad I have the IR station now, last thing I want to do it melt the SD socket and the microswitches. :)

johndimo

#5
Feb 03, 2011, 06:56 pm Last Edit: Feb 03, 2011, 06:58 pm by johndimo Reason: 1
I've seen lots of SOIC parts that have no painted markings or a dimple on one end on them to denote where pin 1 is.

Look at the plastic body. Look and see if one entire side of it is shaved at a 45 angle.

Typically with parts like this, one side of the chip will be a standard 90 degree, the other at around 45 degree.  The side with the angle in it is how you can tell what it is.
Look at the pic below. See the offset in the marking? That's because of the angle in the body. The marking is centered on the flat area.  The leftmost pin on the side with the angle is pin 1.




thegeekway

You are a genius :D

Why dont they put this kind of thing in the datasheets, thankfully I had put it on correctly first time.  Just need to test now.

Thanks!

johndimo


You are a genius :D

Why dont they put this kind of thing in the datasheets, thankfully I had put it on correctly first time.  Just need to test now.

Thanks!


No problem. Good luck with the testing! Hope all goes good.

Grumpy_Mike

Quote
Why dont they put this kind of thing in the datasheets,

They normally do, it is at the end with the package drawings. You might have an edited data sheet or not the data sheet from the manufacturer of your chip.

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