I have built a circuit based on the datasheet application Figure 9. Nonisolated 24V Buck Converter with Optional Undervoltage Lockout (with modified feedback and components due to availability at our distributors, and desired PCB footprint size (for mosfet)).
Unfortunately, I cannot get it to work properly... The output is oscillating weirdly at around 3 volts at a low, visible frequency. Feedback is therefore reaching only a few milivolts.
I have checked all the components, replaced all diodes, mosfet, and the IC itself, re-measured all values and replaced them, to be sure I have got them correct like in the schematic, and that they are working. Find below screenshots of schematic, pcb layout (with other stuff around) and oscilloscope screenshots.
Now I am out of ideas, I have debugged this board for two days now... Any more experienced engineers with ideas? Thank you.