LM2596
Simple switcher Power Converter 150kHz
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 available in fixed output voltages of 3.3V, 5V,
12V, 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 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 regulators. 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 output voltage under specified input voltage and
output load conditions, and
±15%
on the oscillator
frequency. External shutdown is included, featuring
typically 80 UA standby current. 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
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3.3V, 5V, 12V, and adjustable output versions
Adjustable version output voltage range, 1.2V to 37V
±4%
max over line and load conditions
Available in TO-220 and TO-263 packages
Guaranteed 3A output load current
Input voltage range up to 40V
Requires only 4 external components
Excellent line and load regulation specifications
150 kHz fixed frequency internal oscillator
TTL shutdown capability
Low power standby mode, I
Q
typically 80 UA
High efficiency
Uses
readily available standard inductors
Thermal shutdown and current limit protection
APPLICATIONS
Simple high-efficiency step-down (buck) regulator
On-card switching regulators
Positive to negative converter
TYPICAL APPLICATION
(Fixed Output Voltage Versions)
12V
LM2596
5.0
+ 1
2
C
IN
5
3
680
µ
F
+V
IN
4
L1
+C
220
µ
F
OUT
5.0V
BLOCK DIAGRAM
ON/OFF
V
IN
START
UP
2.5V
+
+
COM
-
-
COM
+
R2
GM
+
AMP
-
Active
capacitor
+
-
150kHz
OSC
OUTPUT
GND
-
+
LATCH
DRIVER
+
FEEDBACK
1
FCI [ FIRST COMPONENTS INTERNATIONAL ]
