What does "No Pin" mean in IC pinout?
In general, most companies will use an NC - for Non-connect.  But in this case, it looks like it really seems they do mean No Pin.  Looking at the data sheet, you see that there are two variants of the part, one that uses that pin 5 (Dual output) and one that doesn't (Single output). Having a "No Pin" option allows the board to be designed to minimize part mix-ups during manufacturing, this is important since these packages look very similar and could easily be mixed up. Not having a pin hole will prevent a dual output device from being loaded in that position.

Sometimes, you put in pins and remove them when a part mix up will be dangerous or damaging, but with the pinouts on this part, there probably would not be a big flame out.

Also, since it is a hybrid package, the reduction of one pin will save one millicent (yes that is a joke) which over a production run of millions of units will save manufacturing costs.

There is a little bit of an art to reading a datasheet, so it's not surprising this could be confusing.



Although from the table snipped from the datasheet, it's not at all clear why a single output device would have two outputs ... (see pins 6 &amp; 7)