IC1 LM317LZ 200mA, TO-92 ($0.59) – This is the smallest common LM317 voltage regulator. The part linked can supply 200mA, but 100mA is more common.

The humble LM317 adjustable voltage regulator is everywhere. From wifi routers, to high spec lab equipment. Given a noisy input and a variable load, a voltage regulator will give a nice clean, ...

Take advantage of current control topologies without self-heating error while retaining the 317/337's fault protection ...

The LM317 was trying to force 40 mA into a white light-emitting diode (LED), so that 1.25 V across RS, the 30.1-ohms sense resistor, would cause a 41-mA current to flow—if you had enough voltage.

The LM317 regulator melds with HC4053 CMOS switch to make a 16-W PWM power DAC, charting a less traveled by path to power. ... Its output is proportional to the guaranteed 2% precision of the LM317 ...

Reading through the app note, the transient response to changes in voltage is less than 10 usec and the deviation is small. That seems pretty good for something like a laser diode. More options ...