The LM138/LM238/LM338 are adjustable 3-terminal positive voltage regulators capable of supplying in excess of 5A over a 1.2V to 32V output range. They have features such as adjustable output voltage, excellent load and line regulation, and good thermal stability.
The LM138, LM238, and LM338 are three‑terminal adjustable positive voltage regulators capable of delivering up to 5 A over a 1.2 V to 32 V output range. They offer excellent line and load regulation, thermal regulation, and time‑dependent current limiting, making them suitable for a wide variety of power supply designs.
The document provides electrical characteristics, recommended external capacitors, protection diode guidelines, mechanical data for the TO‑3 package, and typical application circuits. It also lists absolute maximum ratings, ordering codes, and thermal data to aid designers in implementing these regulators safely and efficiently.
| Maximum output current | 5 A |
|---|---|
| Adjustable output voltage range | 1.2 V to 32 V |
| Line regulation (typical) | 0.005 %/V |
| Load regulation (typical) | 0.1 % |
| Operating temperature range (LM138) | -55 °C to 150 °C |
A 0.1 µF disc or 1 µF solid tantalum capacitor is recommended on the input.
The LM338 develops a nominal 1.25 V reference voltage between the output and adjustment terminal.
The maximum input‑output differential voltage is 35 V.
They are supplied in standard steel TO‑3 transistor packages.