LM117/LM317A/LM317 3-terminal adjustable regulator is a 3-terminal adjustable regulator with excellent performance. It is packaged in standard transistor packages and has current limit, thermal overload protection and safe area protection. It is widely used in various electronic circuits.
The LM117 series of adjustable 3‑terminal positive voltage regulators can supply more than 1.5 A over a 1.2 V to 37 V output range. They require only two external resistors to set the output voltage and include built‑in current limit, thermal overload, and safe‑area protection. The device is available in several TO‑style and surface‑mount packages, making it easy to mount in a variety of designs.
The datasheet details absolute maximum ratings, electrical characteristics, typical performance curves, and extensive application hints such as recommended input bypass capacitors, ripple‑rejection techniques, and heatsinking guidelines. Physical dimensions for each package and ordering information are also provided.
| Output current | 1.5 A |
|---|---|
| Output voltage range | 1.2 V – 37 V |
| Line regulation (LM317A) | 0.01 %/V |
| Load regulation (LM117) | 0.3 % |
| Ripple rejection | 80 dB |
| Reference voltage | 1.25 V |
| Package – TO‑3 | 1.5 A |
| Package – TO‑39 | 0.5 A |
| Package – TO‑220 | 1.5 A |
| Package – SOT‑223 | 1 A |
The LM117 develops a nominal 1.25 V reference voltage between the output and adjustment terminals.
The device includes current limit, thermal overload protection, safe‑area protection, and short‑circuit protection that remain functional even if the adjustment terminal is disconnected.
A 0.1 µF disc or a 1 µF solid tantalum capacitor is recommended as an input bypass for most applications.