The MAX638 is a CMOS step‑down switching regulator designed for low‑power DC‑DC conversion with a minimum of three external components. It offers a fixed +5 V output or an adjustable output set by two resistors, low operating current, and typical efficiency of about 85 %. The device is available in 8‑pin plastic DIP and narrow SO packages.
The datasheet includes pin functions, absolute maximum ratings, electrical characteristics, and detailed application guidance such as inductor selection, output filter design, and low‑battery detection. Design tips cover inductor saturation, bypassing, and compensation to ensure stable operation across a wide input voltage range.
| Fixed Output Voltage | +5 V |
|---|---|
| Adjustable Output | Set with 2 external resistors |
| Typical Efficiency | 85 % (typ) |
| External Components Required | 3 |
| Package Options | 8‑Pin Plastic DIP and Narrow SO |
| Peak Output Current Rating | 525 mA |
The MAX638 typically achieves about 85 % efficiency.
Only three external components are required.
The device has a peak output current rating of 525 mA.