Hello,
I noticed the following things about this issue that seem to be significant parts of your issue:
- The output dropping off from 14.4V to 4V at a 250mA load is concerning.
- Light load stabilizes at 5V, which is indicative of regulation issues at heavy load in this application where 4.7V under full load struggles to maintain regulation.
- The impact of doubling the inductance helps with energy storage but doesn’t fully resolve the root cause if he minimum off time is a limiting factor.
Perhaps adjusting your feedback network would add stability to your system. If for some reason this doesn’t work and regulation is still problematic, here is another part that would perhaps be more well suited for your application:
Hopefully this helps,
Krishan