LM1577/LM2577 are monolithic integrated circuits that provide all of the power and control functions for step-up (boost), flyback, and forward converter switching regulators. The device is available in three different output voltage versions: 12V, 15V, and adjustable. Requiring a minimum number of external components, these regulators are cost effective, and simple to use. Features include NPN output switches, wide input voltage range, current-mode operation, 52 kHz internal oscillator, soft-start function, and output switch protection.
The LM1577 and LM2577 are monolithic step‑up (boost), flyback, and forward switching regulators offered in 12 V, 15 V, and adjustable output versions. They integrate a 3 A NPN switch with protection circuitry, a 52 kHz fixed‑frequency oscillator, soft‑start, and current‑mode control for improved transient response.
The document provides electrical characteristics, absolute maximum ratings, thermal data, package dimensions, and ordering information for multiple package types (TO‑220, TO‑263, etc.). It also includes typical application circuits and a life‑support component disclaimer.
| Output voltage versions | 12 V, 15 V, adjustable |
|---|---|
| Input voltage range | 3.5 V to 40 V |
| Switch current rating | 3.0 A (stand‑off 65 V) |
| Oscillator frequency | 52 kHz |
| Package type example | TO‑220 (T) package |
The device uses a fixed‑frequency oscillator operating at 52 kHz.
It accepts an input voltage from 3.5 V up to 40 V.
Yes, a soft‑start function reduces in‑rush current during start‑up.
No, they are not authorized for use as critical components in life‑support devices without written approval.