I have an LM5001BSTEVAL eval board. Because of my application, I have 2000uF on the output. At 2 Hz the output is pulsed at 4 amps for 5 mS. Of course the output droops, which is okay, and the LM5001 charges it back up to 48V in like 80mS. That's fine for my application.
However, working with my local FAE, by looking at the switch node we determined that when the load is applied, and during the 80mS recovery period, there appears to be sub-harmonic oscillation. This is shown in the first image, where the yellow trace is the switch node, the purple trace is the 48V output, and the blue trace is the low end of a low-side switch (zero volts means load on, 48V means load off). You can see that in the attachment the blue is rising, meaning it's the end of the load period.
I did a 0.6 amp pulsed load test without the 2000uF, just to see what the stock eval board does, and it also has sub-harmonic oscillations, although they are not as much difference between cycles, see the second image.
The input voltage is 16V, and there no changes to the eval board.
Is there an issue I should worry about? It could be doing the funcion shown in the first image continuously.
