When constant current isn't constant.... on LED driver.

[Zero999]

I just don't get why people often use the overkill LM317 in applications designed for a few tens of mA. I understand it might make sense for prototyping and to an extent hobbyist use, as stocking only one part is more convenient, than two, but for large production runs it makes more sense to use the smaller and cheaper LM317L. The lower minimum load and current limit are also advantageous, in lower power applications.

I have had to use the TO-220 package 317 even at low currents sometimes to meet power dissipation requirements.  A TO-220 package without any heat sinking is good for 2 watts versus 625 milliwatts for the TO-92 317.

That would make sense, but we're talking about 12mA here. Unless it's very hot, the voltage would have to exceed the LM317L's maximum rating to even get close to the rated power dissipation.

[1sciguy]

I agree. I just don't get why people often use the overkill LM317 in applications designed for a few tens of mA. I understand it might make sense for prototyping and to an extent hobbyist use, as stocking only one part is more convenient, than two, but for large production runs it makes more sense to use the smaller and cheaper LM317L. The lower minimum load and current limit are also advantageous, in lower power applications.

I used it because I already had a whole reel of them on my pick-n-place machine from another higher current application.  Yes, I realize now it was a bad choice, and the LM317L would have also been a bad choice for this application because of my PWM dimming scheme.  Just tested the NSI45015WT1G as others suggested and it works beautifully.  And indeed it fits perfectly on the old LM317 surface mount footprint.  Even though this was "production", we aren't talking millions of copies.  I sell about 200 a year of this particular card, so I wanted to use up my reel of unused LM317's.  Again, poor choice.