National LM1577 LM2577 Series User's Manual
Summary
These advanced monolithic integrated circuits are highly efficient Step-Up Voltage Regulators designed for challenging power applications (Boost, flyback, and forward converters). The LM1577/LM2577 series offers robust performance, requiring minimal external components while maintaining a wide input voltage range of 3.5V to 40V. Features include soft-start functionality, current limiting, and multiple output options (12V, 15V, Adjustable). This technical guide provides engineers with comprehensive details on electrical characteristics, operating ratings, package options, and usage guidelines needed for reliable power solutions in advanced electronic systems.
Page 1 Text Content
LM 1577/LM eries IM LE ITC tep-U Voltage egulator
LM1577/LM2577 Series SIMPLE SWITCHER® Step-Up Voltage Regulator General Description Features
The LM1577/LM2577 are monolithic integrated circuits that Requires few external components
provide all of the power and control functions for step-up NPN output switches 3.0A, can stand off 65V (boost), flyback, and forward converter switching regulators. Wide input voltage range: 3.5V to 40V The device is available in three different output voltage ver- Current-mode operation for improved transient sions: 12V, 15V, and adjustable. response, line regulation, and current limit Requiring minimum number of external components, these k Hz internal oscillator regulators are cost effective, and simple to use. Listed in this Soft-start function reduces in-rush current during start-up data sheet are family of standard inductors and flyback
Output switch protected by current limit, under-voltage
transformers designed to work with these switching regula-
lockout, and thermal shutdown
tors. Included on the chip is 3.0A NPN switch and its associated
Typical Applications
protection circuitry, consisting of current and thermal limiting,
Simple boost regulator
and undervoltage lockout. Other features include k Hz
fixed-frequency oscillator that requires no external compo- Flyback and forward regulators nents, soft start mode to reduce in-rush current during Multiple-output regulator
start-up, and current mode control for improved rejection of input voltage and output load transients.
Typical Application
DS011468-1
Note: Pin numbers shown are for TO-220 (T) package.
Ordering Information Temperature Package Output Voltage NSC Range Type 12V 15V ADJ Package Package
Drawing
−40˚C TA +125˚C 24-Pin Surface Mount LM2577M-12 LM2577M-15 LM2577M-ADJ M24B SO
16-Pin Molded DIP LM2577N-12 LM2577N-15 LM2577N-ADJ N16A 5-Lead Surface Mount LM2577S-12 LM2577S-15 LM2577S-ADJ TS5B TO-263 5-Straight Leads LM2577T-12 LM2577T-15 LM2577T-ADJ T05A TO-220 5-Bent Staggered LM2577T-12 LM2577T-15 LM2577T-ADJ T05D TO-220 Leads Flow LB03 Flow LB03 Flow LB03
−55˚C TA +150˚C 4-Pin TO-3 LM1577K-12/883 LM1577K-15/883 LM1577K- K04A TO-3
ADJ/883
SIMPLE SWITCHER® is registered trademark of National Semiconductor Corporation.
National Semiconductor Corporation DS011468 www.national.com
Page Summary Contents For National LM1577 LM2577 Series User's Manual
Manual Details
| Brand | National |
|---|---|
| Pages | 27 |
| File Size | 911.02 KB |
| Published | May 27, 2026 |
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Frequently Asked Questions
What is the wide input voltage range?
The device supports a wide input voltage range from 3.5V to 40V.
Does it have multiple control modes?
Yes, it offers current-mode operation for improved transient response and includes undervoltage lockout (UVLO) protection.
How is the device simple to use?
It requires a minimum number of external components, making it cost effective and easy to implement. It also features soft-start functionality.
What are the available packaging options?
The device is available in various packages including TO-263 (S), M24B SO, N16A, TS5B, T05A, LBC, and TO-3.