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ADP5052 internal regulator VREG and VDD problems

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

  • Hi Sean,

    Apology for late reply. Yes, I would say the regulator won't work ok if the internal regulator are not fine.

    It is quite strange why you've got previous designs ok while this new one is not ok.  I would start with looking for possible manufacturing issues on the new design board and its PCB layout. You may confirm possible PCB issues by swapping ADP5052 between bad and good boards.