Difference MP4559 and MP4560 on startup

I am successfully using an MP4559 and had to replace it with an MP4560 due to component availability.
This also works as expected, but there is an unexpected difference.
As you can see from the picture, the start-up time of the MP4560 after applying the supply voltage is 7ms, for the MP4559 this is 2ms.
I cannot see this difference from the data sheets, but would like an explanation.

Additional Info: We do not use the EN pin, so this pin ist not connected

Thanks for your help.

Hi Harald,
Our sincere apologies on the delayed response, thank you for utilizing Technical Forum.

There does not seem to be any discernable difference internal architecture. This is an interesting case. The start up and shutdown for the two devices are the same as well.

  1. From what you have described, you simply swapped ICs? and did not change your circuit schematic/components correct?
  2. For how many boards did you implement MP4560?
  3. Can you compare shutdown time?