Features
| • | Requires few external components |
| • | NPN output switches 3.0A, can stand off 65V |
| • | Wide input voltage range: 3.5V to 40V |
| • | Current-mode operation for improved transient response, line regulation, and current limit |
| • | 52 kHz internal oscillator |
| • | Soft-start function reduces in-rush current during start-up |
| • | Output switch protected by current limit, under-voltage lockout, and thermal shutdown |
Description The 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. Listed in this data sheet are a family of standard inductors and flyback transformers designed to work with these switching regulators.
Included on the chip is a 3.0A NPN switch and its associated protection circuitry, consisting of current and thermal limiting, and undervoltage lockout. Other features include a 52 kHz fixed-frequency oscillator that requires no external components, a soft start mode to reduce in-rush current during start-up, and current mode control for improved rejection of input voltage and output load transients.
Applications
| • | Simple boost regulator |
| • | Flyback and forward regulators |
| • | Multiple-output regulator |
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LM1577
