Arduino Forum

Using Arduino => General Electronics => Topic started by: Clemens on Jan 26, 2014, 01:16 am

Title: IC what is Pin 1
Post by: Clemens on Jan 26, 2014, 01:16 am
Normally pin 1 is marked on an IC with a cycle / dot. But how can I find pin 1 on attached IC an ADS1231 http://www.ti.com/lit/ds/symlink/ads1231.pdf
Title: Re: IC what is Pin 1
Post by: Jiggy-Ninja on Jan 26, 2014, 01:36 am
The vertical line on the left is the only thing denoting an asymmetry, so I'd go with that marking pins 1/16.
Title: Re: IC what is Pin 1
Post by: marco_c on Jan 26, 2014, 01:48 am
There seems to be a dot next to the top left hand pin in the photo.
Title: Re: IC what is Pin 1
Post by: TomGeorge on Jan 26, 2014, 08:36 am
Hi, I find this a lot, and yes the line across the end of the chip is 1 and 16 end, there is a faint dot, but its hard to see, and damn near useless.

Tom... :)
Title: Re: IC what is Pin 1
Post by: MarkT on Jan 26, 2014, 01:45 pm
The chamfered edge of the package is the side with pin one (along the
bottom in this picture), this is well documented in relevant datasheets,
consult the datasheet page 21.  You'll find pin numbering is anticlockwise from
above for ICs.   A lot (but not all) of SOIC packaging uses the chamfered
edge convention.
Title: Re: IC what is Pin 1
Post by: Clemens on Jan 27, 2014, 02:48 am
Thank you Mark, I haven't neither noticed the chamfered edge nor the light grey line in the data sheet. But that's it and perhaps the light line is a second indicator.

Interesting is also John's remark. Like reading maps: you know always the North. Is this the case on electronic parts too that writing orientation leads always to pin 1 on the lower left hand side. That makes it easy! Thanks for this helpful hint.
Title: Re: IC what is Pin 1
Post by: CrossRoads on Jan 27, 2014, 06:05 am
The 3rd from last page of the data sheet clearly shows the chamfered edge and pin assignments.
Usually there is no need to guess on these things, just need to read the datasheet.