Introduction: Variable Switching Power Supply Using LM2576 [Buck Converter, CC-CV]

Switching power supplies are known for high efficiency. An adjustable voltage/current supply is an interesting tool, which can be used in many applications such as a Lithium-ion/Lead-acid/NiCD-NiMH battery charger or a standalone power supply. In this article, we will learn to build a variable step-down buck converter using the popular LM2576-Adj chip.


  • Cheap and easy to build and use
  • Constant current and constant voltage adjustment [CC, CV] capability
  • 1.2V to 25V and 25mA to 3A controlling range
  • Easy to adjust the parameters (optimum use of variable resistors to control the voltage and current)
  • The design follows the EMC rules
  • It is easy to mount a heatsink on the LM2576
  • It uses a real shunt resistor (not a PCB track) to sense the current

Step 1: Schematic

Step 2: PCB Layout

Step 3: A 3D/Real View of the Asemblde PCB Board

Step 4: Component Libraries (SamacSys)

Step 5: References