15 Jul
2013
15 Jul
'13
11:36 a.m.
On Monday, July 15, 2013 at 0:14, Josh Dersch wrote:
http://yahozna.dyndns.org/scratch/imlac/fake7475.jpg
The picture's not great, but you can see that pins 4,5,12, and 13 are
connected to asolid piece of metal!
That's a somewhat common arrangement for higher-current peripheral drivers
in DIPs. See, for example, the TI SN754410 Quadruple Half-H Driver, where
those pins are used for heat sinking.
Other chip relabeled to be a 7475?
That's my guess. TI had an SN75xxx series of interface parts. I wondered
if perhaps a 7574 was mislabeled as a 7475, but I can't find a reference to
the former.
Could you post a photo of the top of one of the bad parts that shows the
device marking?
-- Dave