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Switching Power Supply Using LM2596

This DC-DC switching power supply uses the LM2596 step-down (buck) voltage regulator to provide regulated output voltages at up to 3A. The LM2596 can accept a wide input voltage range from 8V to 40V DC and efficiently converts it to a lower DC voltage, making it ideal for battery-powered systems, electronics projects, and embedded applications.

Available Output Versions

  • LM2596-3.3: 3.3V DC output
  • LM2596-5.0: 5V DC output
  • LM2596-12: 12V DC output
  • LM2596-ADJ: Adjustable output from 1.23V to 37V DC using a potentiometer

Power Supply Requirements

  • Input voltage: 8-40V DC (depending on output voltage required).
  • Output current: up to 3A with proper heatsinking and cooling.
  • Filter capacitors for smoothing input and output voltages.
  • Inductor suitable for LM2596 switching to maintain low ripple.

Key Components

  • LM2596 Voltage Regulator: Buck converter IC capable of 3A output.
  • Inductor: Stores energy during switching cycles and smooths output current.
  • Schottky Diode: Provides fast recovery and low voltage drop for the switching output.
  • Input and Output Capacitors: Reduce voltage ripple and stabilize operation.
  • Potentiometer (for LM2596-ADJ): Adjusts output voltage precisely from 1.23V to 37V.

Circuit Operation

  • The input DC voltage (8-40V) is applied to the LM2596 regulator.
  • The LM2596 switches the internal transistor at high frequency, storing energy in the inductor and controlling the output voltage.
  • The Schottky diode and output capacitor smooth the pulsed current into a stable DC voltage.
  • Fixed versions (3.3V, 5V, 12V) deliver regulated voltage automatically, while the adjustable version allows fine-tuning with a potentiometer.
  • High efficiency (>75%) minimizes heat generation compared to linear regulators.

Key Features

  • DC-DC step-down (buck) switching regulator
  • Wide input voltage range: 8V-40V DC
  • Output voltage options: 3.3V, 5V, 12V, or adjustable 1.23V-37V
  • Maximum output current: 3A
  • High efficiency and low heat generation
  • Compact and suitable for embedded systems or battery-powered projects

Construction Notes

  • Ensure proper heatsinking for the LM2596 when operating near maximum current.
  • Use low-ESR capacitors for input and output to maintain stable operation.
  • Choose an inductor rated for the output current and switching frequency of the LM2596.
  • Check Schottky diode rating to handle the maximum load current without overheating.
  • For LM2596-ADJ, adjust the potentiometer carefully to set the desired output voltage.
  • Keep wiring short and thick for high-current connections to reduce voltage drops.
  • LM2596-3.3 (3.3Vdc output)
  • LM2596-5.0 (5Vdc output)
  • LM2596-12 (12Vdc output)
  • LM2596-ADJ (1.23Vdc to 37Vdc output)
Switching PS 5 volts , 3 amper
Print Control board for power supply

Components

  • 680uF 50V electrolytic capacitor
  • 1N5824 high speed schottky diode (5A)
  • Output 100V electrolytic capacitor (higher voltage, lower ESR)
  • 330uF (for LM2596-3.3, LM2596-5.0)
  • 180uF (for LM2596-12)

wire coil inductor

  • 33uH (for LM2596-3.3, LM2596-5.0)
  • 68uH (for LM2596-12)