LM1577/LM2577 Series SIMPLE SWITCHER® Step-Up Voltage Regulator
The LM1577/LM2577 series are monolithic integrated circuits that provide the power and control functions for step‑up (boost), flyback, and forward converter switching regulators. They are available in three output‑voltage versions (12 V, 15 V, and adjustable) and require only a few external components, making them cost‑effective and simple to use.
The devices include a 3.0 A NPN switch with built‑in current, thermal and undervoltage protection, a fixed‑frequency 52 kHz oscillator, soft‑start, and current‑mode control. Detailed electrical characteristics, thermal parameters, and mechanical dimensions are provided for multiple package types such as TO‑220, TO‑263, and surface‑mount variants.
| Output voltage versions | 12 V, 15 V, adjustable |
|---|---|
| Input voltage range | 3.5 V to 40 V |
| Switch current (NPN output) | 3.0 A |
| Oscillator frequency | 52 kHz |
| Maximum duty cycle | 95 % |
The internal oscillator runs at a fixed 52 kHz.
They operate with an input voltage from 3.5 V up to 40 V.
The IC includes current limit, thermal shutdown, and undervoltage lockout protection.