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

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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.

Features

  • 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

Article source: http://bit.ly/2YshM5t

LM2576 Datasheet: https://www.onsemi.com/pub/Collateral/LM2576-D.PDF

LM358 Datasheet: https://www.onsemi.com/pub/Collateral/LM358-D.PDF

LM2576 Library: https://componentsearchengine.com/part-view/LM2576TV-ADJG/ON%20Semiconductor

LM358 Library: https://componentsearchengine.com/part.php?partID=671517

Altium Plugin: https://www.samacsys.com/altium-designer-library-instructions