July 2005
LM2588
SIMPLE SWITCHER® 5A Flyback Regulator with
Shutdown
General Description
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
The LM2588 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.
n Adjustable switching frequency: 100 kHz to 200 kHz
n External shutdown capability
n Draws less than 60 µA when shut down
n Frequency synchronization
n Current-mode operation for improved transient
response, line regulation, and current limit
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
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 an adjustable frequency oscillator that can be pro-
grammed up to 200 kHz. The oscillator can also be synchro-
nized with other devices, so that multiple devices can oper-
ate at the same switching frequency.
Typical Applications
n Flyback regulator
n Forward converter
n Multiple-output regulator
n Simple boost regulator
Other features include soft start mode to reduce in-rush
current during start up, and current mode control for im-
proved rejection of input voltage and output load transients
and cycle-by-cycle current limiting. The device also has a
shutdown pin, so that it can be turned off externally. An
output voltage tolerance of 4%, within specified input volt-
ages and output load conditions, is guaranteed for the power
supply system.
Connection Diagrams
Bent, Staggered Leads
7-Lead TO-220 (T)
Top View
Bent, Staggered Leads
7-Lead TO-220 (T)
Side View
01242018
01242017
Order Number LM2588T-3.3, LM2588T-5.0,
LM2588T-12 or LM2588T-ADJ
See NS Package Number TA07B
®
SIMPLE SWITCHER® and Switchers Made Simple are registered trademarks of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation
DS012420
www.national.com