You’ve probably noticed the LM317 shows up in lots of electronics projects, and that’s because it’s super reliable and easy to dial in. Basically, it lets you set voltages anywhere from about 1.2 V to 37 V, and it can pump out up to 1.5 A. This guide’s got you covered—from what the pins do, to what other parts drop right in, and even a tested circuit with practical advice so you can build it without any headaches.
LM317 Key Characteristics
· Adjustable voltage: 1.25 V to 37 V
· Output current: up to 1.5 A (with heatsink)
· Dropout voltage: ≈3 V
· Regulation: good line and load regulation
· Protections: thermal shutdown, short-circuit, current limiting, safe-area
· Accuracy: adjust-pin current ~50–100 µA → low error
· Stability: internally compensated; input/output capacitors recommended
· Temp range: –55 °C to +125 °C
· Package: TO220 / TO263, easy to heatsink
LM317 Pinout
The LM317 in a TO‑220/TO‑263 package has three pins: