Hi,
my customer is using TPS54331 to generate 3.3V from 5V input, the schematic is as below:
The output 3.3V is to power C2000 MCU and pull up source of some comparator output. Most of the time the device can work normally. But sometimes the device will stop switching, the waveform is as below:
CH1(YELLOW) 5V input, CH2(BLUE) 3.3V output, CH3(purple) PH pin, CH4(green) BOOT pin.
By zoom out the waveform is:
By doing math BOOT-PH, we can see that the boot capacitor voltage gradually decrease to 2.4V and then the device stop switching.
It seems that the problem is caused by boot capacitor UVLO. But we've no idea why it will behave like this. We start the circuit 100 times, and could see it happen about 10 times.
