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
power supplies.
Other features include a guaranteed
±
4% tolerance on out-
put voltage within specified input voltages and output load
conditions, and
±
10% on the oscillator frequency. External
shutdown is included, featuring 50 µA (typical) standby cur-
rent. The output switch includes cycle-by-cycle current limit-
ing, as well as thermal shutdown for full protection under
fault conditions.
Features
n
3.3V, 5V, 12V, 15V, and adjustable output versions
n
Adjustable version output voltage range,
1.23V to 37V (57V for HV version)
±
4% max over
line and load conditions
n
Guaranteed 1A output current
n
Wide input voltage range, 40V up to 60V for HV version
n
Requires only 4 external components
n
52 kHz fixed frequency internal oscillator
n
TTL shutdown capability, low power standby mode
n
High efficiency
n
Uses readily available standard inductors
n
Thermal shutdown and current limit protection
n
P
+
Product Enhancement tested
Applications
n
Simple high-efficiency step-down (buck) regulator
n
Efficient pre-regulator for linear regulators
n
On-card switching regulators
n
Positive to negative converter (Buck-Boost)
Typical Application
(Fixed Output Voltage
Versions)
01147501
Note:
Pin numbers are for the TO-220 package.
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation.
August 2004
LM1575/LM2575/LM2575HV
Series
SIMPLE
SWITCHER
1A
Step-Down
V
oltage
Regulator
© 2004 National Semiconductor Corporation
DS011475
www.national.com
