SNOS658D – JUNE 1999 – REVISED APRIL 2013
LM1577/LM2577 SIMPLE SWITCHER
®
Step-Up Voltage Regulator
Check for Samples:
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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.
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TYPICAL APPLICATIONS
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Simple Boost Regulator
Flyback and Forward Regulators
Multiple-output Regulator
Connection Diagrams
Figure 1. 5-Lead (Straight Leads) TO-220 (T) – Top
View
See Package Number KC
Figure 2. 5-Lead (Bent, Staggered Leads) TO-220
(T) – Top View
See Package Number NDH0005D
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
SIMPLE SWITCHER is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
Copyright © 1999–2013, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
TI [ TEXAS INSTRUMENTS ]
