TPS65094: TPS650940 does not work probabilistically during the boot process

Hi All,

Our Gemini Lake N4120 project uses the PMIC TPS650940, but during the test we found a big problem. That is, there is about 10% probability appears directly power failure or a black screen during the boot process (the power of the VCGI is lost, and the PMIC is not working normally). The specific phenomena are as follows:

1) PMIC BUCK4 (normal working voltage 1.8V) drops to 1.5V and BUCK5 (normal working voltage 1.24V) drops to 1.0V;

2) The notebook shuts down directly;

3) The power of the VCGI is lost only;

The power-on sequence and Buck4 waveform are shown as follows:

a. Power-on sequence waveform (the yellow is PMIC_EN, the blue is RSMRST_N, the purple is PMU_RSMRST_N, the green is PMU_PWRBTN_N)

b. Waveform diagram of Buck4 (the purple is Buck4)

I added my schematic to the following and hope it can do some help with the problem analysis.

TPS65094X.pdf

Thanks,

Best Regards