Lesson Learned... Or Not
Recently, I was looking in my Eagle library for a low-drop out regulator, MC39100 is SOT223. It's just a standard, run of the mill 7805 replacement. Nothing special. A million other parts share the same pin-out. Shouldn't be a problem. Shouldn't...
If I were to follow my own advice, it wouldn't have been a problem. But did I follow my own advice? Well, not this part of it. I took for granted that all three terminal regulators follow the 78XX pin-out. Most do, but the LD1117A (below, left) does not. This isn't the first time I've used a non-standard regulator, so I really don't have an excuse.
Naturally, I assumed that the pin-out matched what I needed and I didn't hunt down an LD1117A data sheet to verify their pin-out. Well, at least I didn't do so until trying to get my new PCB to power up. Very sad.
So, is there a moral to this story? Probably. Most likely it would be two-fold. One, if you're re-purposing a land pattern from a part that's close, but not exact, double check your work. Get both data sheets out and compare the pin-out.
The second part of the moral is, if you give adice... follow it yourself. Duh.
Help! I'm blinded by the obvious.