LM2596 SIMPLE SWITCHER Power Converter 150 kHz 3A Step-Down Voltage Regulator
May 2002
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 µA 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 µA
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
Versions)
(Fixed Output Voltage
01258301
SIMPLE SWITCHER
®
and
Switchers Made Simple
®
are registered trademarks of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
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