This project is the design of a DC-DC buck regulator module based on the AP64501.
It is mechanically and electrically compatible with the popular LM2596-based low-cost Chinese modules, using the same form factor, size, and pinout.
However, this design provides significant improvements in terms of efficiency, thermal performance, EMI, and reliability.

🔑 Key Features

• Synchronous buck regulator (AP64501)

  • Higher efficiency compared to asynchronous regulators.

  • Reduced heat generation under load.

• Fixed Spread Spectrum (FSS)

  • Lower EMI and more predictable spectral content.

• Soft-Start (SS)

  • Controlled inrush current during power-up.

• Protections included

  • Overcurrent protection (OCP).

  • Overvoltage protection (OVP).

  • Thermal shutdown (TSD).

• Output filtering

  • Additional LC filter stage for significantly reduced ripple.

• PCB design

  • 4-layer PCB for improved heat spreading and ground integrity.

  • Optimized layout for EMI and thermal performance.

• Thermal analysis

  • Finite Element Analysis (FEA) performed.

  • Effective thermal resistance: 55 °C/W (with 1 oz copper).

📐 Form Factor

• Pinout, size, and footprint are drop-in compatible with standard LM2596-based modules.

• This allows easy replacement in existing designs, providing an immediate upgrade without redesigning the host PCB.

📊 Performance Advantages over LM2596 Modules

• ✅ Higher efficiency → less power loss.

• ✅ Lower EMI thanks to fixed-frequency operation and optimized layout.

• ✅ Lower output ripple due to additional LC stage.

• ✅ Improved thermal performance with 4-layer PCB and synchronous design.

• ✅ Built-in protections increase reliability and robustness.

🛠 Applications

• Embedded systems.

• IoT devices.

• RF front-ends (low-ripple supply requirement).

• General-purpose regulated DC power supply.

• Replacement for LM2596 modules in existing projects.

📄 Documentation

• AP64501 Datasheet (Diodes Incorporated)

• Thermal FEA analysis results included in /docs.

• PCB design files in /hardware.

🚀 Status

• ✅ Schematic design complete.

• ✅ PCB layout (4-layer) completed.

• ✅ Thermal simulation results validated.

• 🔜 Hardware prototyping and testing in progress.

📷 Preview

(Add photos, renderings, or thermal plots here when available.)

📜 License

This project is released under the MIT License.
See the LICENSE file for details.