1.2V to 35V @ 3A Adjustable Step-down Regulator using LM2596

This is a highly efficient and compact project that is capable of driving a 3A load with excellent line and load regulation and adjustable output of 1.2V to 35V DC.  The project is built around the LM2596-ADJ regulator which is ideally suited for easy and convenient design of step-down switching regulator using buck converter topology. The adjustable output version of LM2596 is internally compensated to minimize the number of external components to simplify the power supply design.

LM2596 – 3.0 A, Step-Down Switching Regulator

The LM2596 regulator is a monolithic integrated circuit ideally suited for easy and convenient design of a step−down switching regulator (buck converter). It is capable of driving a 3.0 A load with excellent line and load regulation. This device is available in adjustable output version and it is internally compensated to minimize the number of external components to simplify the power supply design. Since LM2596 converter is a switch−mode power supply, its efficiency is significantly higher in comparison with popular three−terminal linear regulators, especially with higher input voltages. The LM2596 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 standard5−lead TO−220 package with several different lead bend options, and D2PAK surface-mount package. The other features include a guaranteed 4% tolerance on output voltage within specified input voltages and output load conditions, and +/-15% on the oscillator frequency. External shutdown is included, featuring 80 uA (typical) standby current. Self-protection features include switch cycle−by−cycle current limit for the output switch, as well as thermal shutdown for complete protection under fault conditions.

Features

  • Adjustable Output Voltage Range 1.23 V to 35 V
  • Guaranteed 3 A Output Load Current
  • Wide Input Voltage Range 3.2V to 40 V
  • Input must be >1.5V higher than the output
  • High Efficiency Up to 92%
  • 150 kHz Fixed Frequency Internal Oscillator
  • Thermal Shutdown and Current Limit Protection
  • Internal Loop Compensation
  • Precise potentiometer for voltage adjustment
  • Output Ripple: ≤100mV
  • PCB dimensions 57.15 x 44.34 mm

Schematic

Block Diagram

Pin Out

Parts List

PartValuePackageLCSC.com
R150k ±10% Precision PotTHC118911
R21.21K 1%SMD 0805C228373
R34k7SMD 0805C229219
L133uH/5ASMD 12MM INDUCTORC439422
C2 C3220uF/50VSMD ELECTROLYTICC3358
C1100uF/50VSMD ELECTROLYTICC249588
IC1LM2596-ADJTO263 SMDC29781
D1MBRS340T3SMCC40326
D2RED LEDSMD 0805C192318
CN1 CN22 PIN SCREW TERMINALSTHC409161

Connections

Gerber View



Measurements

CH1: Output Voltage ripple with 30V Input and 12V @ 1A output – 277 mVpp
CH1: Output Voltage ripple with 30V Input and 12V @ 1A output – 277mVpp – CH2: Output at PIN 2 of IC – 156kHz switching frequency
CH1: Output Voltage ripple with 30V Input and 12V @ 3A output – 233 mVpp
CH1: Output Voltage ripple with 30V Input and 12V @ 3A output – CH2: Output at PIN 2 of IC – 147kHz switching frequency

 

Thermal Performance

30V Input and 12V @ 1A output -reaches close to 50 Celsius
30V Input and 12V @ 3A output – reaches close to 90 Celsius

Photos

 

 

Video

LM2596-ADJ Datasheet

lm2596

PCB

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