Pinout
LM317 adjustable regulator (TO-220) pinout
Pins
- 1 ADJ (left, facing the label)
- 2 VOUT (middle — also the tab)
- 3 VIN (right)
- VOUT = 1.25V × (1 + R2/R1); pinout differs from the 7805 — do not swap them blindly
Specifications
| Output voltage | 1.25–37 V, set by two resistors |
|---|---|
| Output formula | Vout = 1.25 V × (1 + R2/R1); R1 typically 240 Ω |
| Input–output differential | 3–40 V recommended |
| Output current | Up to 1.5 A with adequate heatsinking |
| Reference voltage | 1.25 V typ (1.2–1.3 V) |
| ADJ pin current | ≈ 50 µA typ |
| Minimum load current | ≈ 3.5 mA typ, 10 mA max (R1 usually provides it) |
| Protection | Current limit, thermal shutdown, safe-area protection |
| Operating junction temperature | 0–125 °C |
| Package | TO-220 (also TO-92 LM317L at 100 mA, D2PAK, SOT-223) |
