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LM1575/LM2575/LM2575HV Series SIMPLE SWITCHER 1A Step-Down Voltage Regulator
April 2007
LM1575/LM2575/LM2575HV
SIMPLE SWITCHER
®
1A Step-Down Voltage Regulator
General Description
The LM2575 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 1A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.
The LM2575 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially re-
duces the size of the heat sink, and in many cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2575 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode pow-
er supplies.
Other features include a guaranteed ±4% tolerance on output
voltage within specified input voltages and output load con-
ditions, and ±10% on the oscillator frequency. External shut-
down is included, featuring 50
μA
(typical) standby current.
The output switch includes cycle-by-cycle current limiting, as
well as thermal shutdown for full protection under fault con-
ditions.
Features
■
3.3V, 5V, 12V, 15V, and adjustable output versions
■
Adjustable version output voltage range,
■
■
■
■
■
■
■
■
■
1.23V to 37V (57V for HV version) ±4% max over
line and load conditions
Guaranteed 1A output current
Wide input voltage range, 40V up to 60V for HV version
Requires only 4 external components
52 kHz fixed frequency internal oscillator
TTL shutdown capability, low power standby mode
High efficiency
Uses readily available standard inductors
Thermal shutdown and current limit protection
P
+
Product Enhancement tested
Applications
■
■
■
■
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
Typical Application
(Fixed Output Voltage Versions)
1147501
Note:
Pin numbers are for the TO-220 package.
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation
© 2007 National Semiconductor Corporation
11475
www.national.com
LM1575/LM2575/LM2575HV
Connection Diagrams
(XX indicates output voltage option. See Ordering Information table for complete part number.)
Straight Leads
5–Lead TO-220 (T)
Bent, Staggered Leads
5-Lead TO-220 (T)
1147524
1147522
1147523
Top View
LM2575T-XX or LM2575HVT-XX
See NS Package Number T05A
Top View
Side View
LM2575T-XX Flow LB03 or
LM2575HVT-XX Flow LB03
See NS Package Number T05D
16–Lead DIP (N or J)
24-Lead Surface Mount (M)
1147525
*No Internal Connection
Top View
LM2575N-XX or LM2575HVN-XX
See NS Package Number N16A
LM1575J-XX-QML
See NS Package Number J16A
1147526
*No Internal Connection
Top View
LM2575M-XX or LM2575HVM-XX
See NS Package Number M24B
TO-263(S)
5-Lead Surface-Mount Package
1147529
Top View
1147530
Side View
LM2575S-XX or LM2575HVS-XX
See NS Package Number TS5B
3
www.national.com
Embedded System
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