DIY Power Supply Fix with XL4016 and LM358

As the BUCK control IC, the XL4016, was used with the LM358 as the current loop control to create an adjustable power supply with voltage regulation and current limiting. The schematic was drawn using the XL4016 specification book and the design was created using the Lichuang EDA software.

 A 3D model was also created.

After the PCB arrived, it can't wait to solder  the 20mΩ current sampling resistor  onto the board.

Surface-mount components were soldered in place, with room left for capacitors and screws.

The heat sink, diode, XL4016, and meter were then connected.

The potentiometer was installed and the power supply was connected to a 24V source, resulting in immediate start-up.

However, without proper inspection, it was discovered that a capacitor was soldered in the wrong direction, causing the display to not function. Further investigation revealed that the feedback (FB) pin was above 3.3V and the power supply was in protection mode.

To resolve this issue, the current loop was disconnected and the D5 pin of the schematic was removed, allowing for proper voltage adjustment.

Upon further inspection, it was discovered that the B and E terminals of two transistors were mislabeled in the schematic, causing no errors in the software's DRC check. The IC was re-soldered and the D5 diode was connected, allowing for proper display and current limiting.

Overall, the following lessons were learned:

1. After soldering, it is crucial to carefully inspect the board to avoid any malfunctions.

2. A potentiometer that can be rotated multiple times should be used to enable smoother voltage regulation and current limiting.

3. The current limiting circuit requires further improvement to prevent automatic reset and ensure manual reset is necessary after reaching the limit.

4. Input protection, such as a diode or MOS, and safety features, such as a fuse, should be added to the design.