May I know what is the pre-biased loads start up function of MP8770? since we need clealfy currently start up issue.
It can be seen that during the startup, the output voltage drops and gate stop.
Could you let us know what your input conditions are? Is it possible the input current limit is too low? The first picture show shows your input of 12V. However, the second shows it barely above 8V. The device also looks to be operating in hiccup mode which is triggered by UV or OCP. I don’t think it is OCP because this is an 8A continuous device.
This phenomenon can also be measured in EVB, the test condition as following
Vin 12V, Vout 5V, E-load CC mode 0.1A
Vin 12V, Vout 1V, E-load CC mode 0.1A
Noted the phenomenon no happen at no load condition