TPS54425: Regarding momentary interruption of input power

Hi,

It's caused by UVP function. This function is latch so once it is triggered, needs a total power off and on to recover. Inside the device, there's a 5V power supply for internal controller and VREG5 is a branch of it. So in your first waveform, the VREG5 is not low enough so it keeps controller's UVP logic state, then although VIN recovers, the devices keeps UVP state and cannot startup. But in second waveform, the VREG5 voltage is lower then make internal controller lose its logic state. So it can restart.

Regards,

Shipeng

Thank you for answering.

To what volts does VREG5 need to be lowered? Also, how can I lower VREG5 quickly?

Hi Shinji

Shipeng will get back to you next Monday.

Thank you

Thank you for answering.

As shown in Figure 13, R4 (100 kΩ) is inserted between VREG5 and PG, but would it be okay to make R4 smaller?

Or would it be okay to add a resistor of about 100 Ω in parallel to C7?