I have implemented a WebBench design of the LM43600 with +24VDC input and a +12V output with .5A max load. The circuit starts up correctly most of the time. But when starting cold there is an occasional instability that resembles starting and stopping every ~20msec. Here's a (blurry) picture.
But most of the time the circuit works correctly, like this.
Here's the web bench design
The layout is tight and should not be the problem. Here's a view of the layout.
Unfortunately, with even the slightest possibility of a startup problem, we can't use this design. Can anyone recommend some sort of fix?