MP8770 Start up issues

Dear Sir,

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.

Vin =12V Vout=5V Iout=6A
CH1: VIN, CH2:SW, CH3:EN, CH4: Vout


MP8770 EVB
mp8770 evb

Hello john.du,

The pre-bias startup can be see here:
image

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.
image

Thank you,
Vinh Tran
Field Applications Engineer

Dear Sir,

thanks!

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