LM2587_04 Datasheet, PDF (1/27 Pages) National Semiconductor (TI) – SIMPLE SWITCHER® 5A Flyback Regulator

February 2004
LM2587
SIMPLE SWITCHER^® 5A Flyback Regulator
General Description
The LM2587 series of regulators are monolithic integrated
circuits specifically designed for flyback, step-up (boost), and
forward converter applications. The device is available in 4
different output voltage versions: 3.3V, 5.0V, 12V, and ad-
justable.
Requiring a minimum number of external components, these
regulators are cost effective, and simple to use. Included in
the datasheet are typical circuits of boost and flyback regu-
lators. Also listed are selector guides for diodes and capaci-
tors and a family of standard inductors and flyback trans-
formers designed to work with these switching regulators.
The power switch is a 5.0A NPN device that can stand-off
65V. Protecting the power switch are current and thermal
limiting circuits, and an undervoltage lockout circuit. This IC
contains a 100 kHz fixed-frequency internal oscillator that
permits the use of small magnetics. Other features include
soft start mode to reduce in-rush current during start up,
current mode control for improved rejection of input voltage
and output load transients and cycle-by-cycle current limit-
ing. An output voltage tolerance of ±4%, within specified
input voltages and output load conditions, is guaranteed for
the power supply system.
Features
n Requires few external components
n Family of standard inductors and transformers
n NPN output switches 5.0A, can stand off 65V
n Wide input voltage range: 4V to 40V
n Current-mode operation for improved transient
response, line regulation, and current limit
n 100 kHz switching frequency
n Internal soft-start function reduces in-rush current during
start-up
n Output transistor protected by current limit, under
voltage lockout, and thermal shutdown
n System Output Voltage Tolerance of ±4% max over line
and load conditions
Typical Applications
n Flyback regulator
n Multiple-output regulator
n Simple boost regulator
n Forward converter
Flyback Regulator
Ordering Information
Package Type
5-Lead TO-220 Bent, Staggered Leads
5-Lead TO-263
5-Lead TO-263 Tape and Reel
01231601
NSC Package
Order Number
Drawing
T05D
LM2587T-3.3, LM2587T-5.0, LM2587T-12, LM2587T-ADJ
TS5B
LM2587S-3.3, LM2587S-5.0, LM2587S-12, LM2587S-ADJ
TS5B
LM2587SX-3.3, LM2587SX-5.0, LM2587SX-12,
LM2587SX-ADJ
SIMPLE SWITCHER^® and Switchers Made Simple^® are registered trademarks of National Semiconductor Corporation.
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