Hi
I am using TPS54040 to transfer voltage from 12V to 3.3V, but somehow the output voltage drop to 1.8V or 0.7V in some of the products after assemble. In the following are my waveforms and PCB layout. Sometimes it became normal when I remove the glue filling of the products and test the PCB, sometimes it not. So I assume it should be some noise that has affect on the pins of IC, could you pls give some advices on this cases and tell me what reasons may cause this? thanks a lot!
CH1:VIN(12V) CH2:EN CH3:VOUT
CH1:PH CH2:COMP CH3:VOUT
CH1: PH CH2:COMP CH3: VOUT CH4:BOOT
Manu