A switching regulator (TPS63030) on my power management board is showing a weird problem after I opted to re-adjust the voltage output.
Note that this particular board has been used successfully in almost 2000 products.
Recently, due to the ongoing chip shortage, I had to change some ICs (FPGA, memories etc.) and as per their requirement, I needed to change the output voltage of a couple of switching regulators. So, I asked my PCB manufacturer to swap the corresponding switching regulators' voltage-adjusting resistors on some boards already manufactured to make them compatible with the updated design. Since then, the switching regulators with updated resistors output weird voltages in almost 5 out of 10 PCBs. For example, for a particular regulator, the voltage that was supposed to go from 6V to 7V after this change is sometimes 2V, 4.5V, 6.2V or any other random value. See the snapshots of circuit and layout. R47 and R48 are the voltage-adjusting resistors in this example.
Both regulators have similar circuit and layout (with different resistors values obviously,) and they are showing similar problems after the resistor change.
I have tried to resolve the issue by changing the resistor values, tolerances, etc. but to no avail.