The LM2599 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 3A 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 LM2596 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 LM2599 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. A standard series of inductors (both through hole and surface mount types) are available from several different manufacturers optimized for use with the LM2599 series. This feature greatly simplifies the design of switch-mode power supplies. Other features include a guaranteed ±4% tolerance on output voltage under all co
The LM2599 series are monolithic step‑down (buck) switching regulators that provide up to 3 A output current with excellent line and load regulation. They operate at a fixed 150 kHz switching frequency and are available in fixed 3.3 V, 5 V, 12 V, and an adjustable version (1.2 V‑37 V). The devices include shutdown/soft‑start control, error‑flag output, and low‑power standby mode.
Typical applications include high‑efficiency step‑down regulators, pre‑regulators for linear regulators, on‑card switching supplies, and positive‑to‑negative converters. The datasheet provides absolute maximum ratings, electrical characteristics, typical performance curves, package dimensions, and layout guidelines.
| Switching frequency | 150 kHz |
|---|---|
| Maximum input voltage (Vin) | 45 V |
| Output current (continuous) | 3 A |
| Efficiency (typical) | up to 90 % (Vin=25 V, Iout=3 A) |
| Standby (quiescent) current | ≈80 µA |
| Package types | 7‑lead TO‑220 (through‑hole) and 7‑lead TO‑263 (surface‑mount) |
| Adjustable output voltage range | 1.2 V – 37 V |
The LM2599 uses a fixed 150 kHz internal oscillator.
The device is guaranteed to deliver up to 3 A of output current.
It is offered in a 7‑lead TO‑220 through‑hole package and a 7‑lead TO‑263 surface‑mount package.
Efficiency can reach up to 90 % when operating from a 25 V input at a 3 A load.