
LM2596
SIMPLE SWITCHER Power Converter 150 kHz
3A Step-Down Voltage Regulator
General Description
The LM2596 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 3A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, and an adjust-
able 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 LM2596 series operates at a switching frequency of
150 kHz thus allowing smaller sized filter components than
what would be needed with lower frequency switching regu-
lators. Available in a standard 5-lead TO-220 package with
several different lead bend options, and a 5-lead TO-263
surface mount package.
A standard series of inductors are available from several
different manufacturers optimized for use with the LM2596
series. This feature greatly simplifies the design of
switch-mode power supplies.
Other features include a guaranteed ±4% tolerance on out-
put voltage under specified input voltage and output load
conditions, and ±15% on the oscillator frequency. External
shutdown is included, featuring typically 80 A standby cur-
rent. Self protection features include a two stage frequency
reducing current limit for the output switch and an over
temperature shutdown for complete protection under fault
conditions.
Features
n
3.3V, 5V, 12V, and adjustable output versions
n
Adjustable version output voltage range, 1.2V to 37V
±4% max over line and load conditions
n
Available in TO-220 and TO-263 packages
n
Guaranteed 3A output load current
n
Input voltage range up to 40V
n
Requires only 4 external components
n
Excellent line and load regulation specifications
n
150 kHz fixed frequency internal oscillator
n
TTL shutdown capability
n
Low power standby mode, I
Q typically 80 A
n
High efficiency
n
Uses readily available standard inductors
n
Thermal shutdown and current limit protection
Applications
n
Simple high-efficiency step-down (buck) regulator
n
On-card switching regulators
n
Positive to negative converter
Note: Patent Number 5,382,918.
Typical Application (Fixed Output Voltage
Versions)
01258301
SIMPLE SWITCHER and
Switchers Made Simple are registered trademarks of National Semiconductor Corporation.
May 2002
LM2596
SIMPLE
SWITCHER
Power
Converter
150
kHz
3A
Step-Down
V
oltage
Regulator
2002 National Semiconductor Corporation
DS012583
www.national.com