The LM2598 series is a monolithic integrated circuit that provides all the active functions for a step-down (buck) switching regulator, capable of driving a 1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, and an adjustable output version. This series of switching regulators is similar to the LM2595 series, with additional supervisory and performance features added. Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation, improved line and load specifications, fixed-frequency oscillator, Shutdown /Soft-start, error flag delay and error flag output. The LM2598 series operates at a switching frequency of 150 kHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Available in a standard 7-lead TO-220 package with several different lead bend options, and a 7-lead TO-263 surface mount package. Typically, for output voltages less than 12V, and ambient temperatures less than 50˚C, no heat sink is required. A standard series of inductors (both through hole and surface mount types) are available from several different manufacturers optimized for use with the LM2598 series. This feature greatly simplifies the design.
The LM2598 series provides a monolithic step‑down (buck) switching regulator capable of delivering 1 A with excellent line and load regulation. It is available in fixed output versions of 3.3 V, 5 V, 12 V and an adjustable version (1.2 V‑37 V), and operates at a 150 kHz fixed‑frequency internal oscillator.
The device is offered in a 7‑lead TO‑220 (through‑hole) package and a 7‑lead TO‑263 surface‑mount package, with typical applications including high‑efficiency buck conversion, pre‑regulation for linear regulators, and positive‑to‑negative conversion. Detailed electrical characteristics, absolute maximum ratings, and typical performance graphs are provided.
| Switching frequency | 150 kHz |
|---|---|
| Maximum supply voltage (VIN) | 45 V |
| Output current | 1 A |
| Fixed output versions | 3.3 V, 5 V, 12 V |
| Adjustable output range | 1.2 V – 37 V |
| Efficiency (12 V in, 1 A out) | 78 % |
| Thermal resistance (TO‑220, junction‑to‑ambient) | 50 °C/W |
The LM2598 operates at a fixed switching frequency of 150 kHz.
The device is guaranteed to deliver up to 1 A of output current.
Fixed output versions are provided for 3.3 V, 5 V, and 12 V.