I have a design that we just got back from a CM that is not working. We reused the ADP5052 portion that we have used on 3 other designs before that worked great. On the new board the VREG is reading 1.8 instead of the 5.1 we read on an old design that is working and on VDD we read 0.8 whereas we read 3.3V on the old design.
We have replaced the chip, we have verified that the traces are not shorted to ground, and we have replaced the 1uF output caps all to no avail. We are at a total loss as to why these internal LDOs are not working.
Any thoughts?
Also, I am assuming that the main regulators will not switch correctly without these internal LDOs working correctly. Is this a correct assumption?
Thank you for any insight.
Sean