This is a very inexpensive voltage regulator IC. Which can be either used as a fixed voltage regulator or variable voltage regulator.
It just needs only two resistors for setting the output voltage.
LM317 is made by different companies. ST, Ti, On Semi, CDIL, HTC Korea etc.
For setting the output voltage
V(output) = [ V(reference) * ( 1 + R2/R1) ] + [ I(adjustment) * R2 ]
Vref = 1.25V
I(adj) = 50 uA
For setting 5 V at the output
R2 = 2.2k + 680 ohm
R1 = 1k ohm
There are many version of this chip
Lm317M for 500mA maximum current
LM317T for 1.5A max current
LM317L for 100mA max current
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