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 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 µA 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

• 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, IQ typically 80 µA
• 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

Note: †Patent Number 5,382,918.

Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Maximum Supply Voltage 45V
ON /OFF Pin Input Voltage −0.3 ≤ V ≤ +25V
Feedback Pin Voltage −0.3 ≤ V ≤+25V
Output Voltage to Ground (Steady State) −1V
Power Dissipation Internally limited
Storage Temperature Range −65˚C to +150˚C
ESD Susceptibility Human Body Model (Note 2) 2 kV
Lead Temperature
S Package
Vapor Phase (60 sec.) +215˚C
Infrared (10 sec.) +245˚C
T Package (Soldering, 10 sec.) +260˚C
Maximum Junction Temperature +150˚C

Operating Conditions
Temperature Range −40˚C ≤ T_J ≤ +125˚C
Supply Voltage 4.5V to 40V

Typical Application (Fixed Output Voltage Versions)
Connection Diagrams and Ordering Information

Block Diagram

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