MP8017 Load regulation

We designed the MP8017 into a new product. During testing we have found that the load regulation is not very good. Swings over 1v from no load (5.6v) to full load (4.5v). I tested the demo board and see similar results so it does not appear to be a layout issue.

The load regulation graph in the eval board app note shows output voltage varying from approx 5.2v at no load to 5v at full load with a 48v input. Using a 48v input I’m seeing over 1v as described above.

Suggestions?

Update:

Input 48V, Design is per the data sheet for primary side feedback.

Demo board, no load on the output, 6.317V

Demo board 2.2A load on the output 4.716V

Our board, no load, 5.338V

Our board, 2.2A load, 4.717V

As you can see, regulation over output load is not very good.

Looking for suggestions on how to tighten up the regulation range.